Tanscriber's note:

Text enclosed by equal signs was in bold face in the original (bold).



THE NORTH AMERICAN SLIME-MOULDS

The Macmillan Company New York . Boston . Chicago . Dallas Atlanta . San Francisco

Macmillan & Co., Limited London . Bombay . Calcutta Melbourne

The Macmillan Co. of Canada, Ltd. Toronto



THE NORTH AMERICAN SLIME-MOULDS

A Descriptive List of All Species of Myxomycetes Hitherto Reported from the Continent of North America

With Notes on Some Extra-Limital Species

by

THOMAS H. MACBRIDE State University of Iowa

New and Revised Edition



New York The Macmillan Company London: Macmillan and Co., Ltd. 1922

All rights reserved

Copyright, 1899, By The Macmillan Company.

Copyright, 1922, By The Macmillan Company.

The Clio Press Iowa City, Iowa, U. S. A.



. IN . MEMORIAM . . SAMUELIS . CALVINI . . SCIENTIAE . NATURALIS . IN . UNIVERSITATE . IOWENSI . . NUPER . PROFESSORIS . . PRAECEPTORIS . COMITIS . AMICI . . HUNC . LIBRUM . . GRATO . ANIMO . DEDICAT . . DISCIPULUS .

"Ihr naht euch wieder schwankende Gestalten, Die frueh sich einst dem trueben Blick gezeigt."

GOETHE.

"Diese Kinder der Natur, welche aus einer ungeformten Gallert, und einem unsichtbaren Saamen entstehen, sind im stande, in dem sie sich nach und nach entwickeln und ihre scheinbar nachlaessige Bildung genau beobachten (lassen), eben so sehr als die schoenste Pflanze, einem empfindenden Herzen die tiefe Achtung und das paradiesische Vernuegen zu verschaffen, welches einzig die Betrachtung der Heere der Natur und ihre gleichbleibende Erhaltung durch eine ewige Kraft hervorbringen kann."

A. J. G. C. BATSCH 1783.



TABLE OF CONTENTS

PAGE

PREFACE ix

PREFACE TO SECOND EDITION xiii

BIBLIOGRAPHY xv

INTRODUCTORY 1

THE MYXOMYCETES 17

ADDENDA 282

INDEX OF GENERA 289

INDEX OF SPECIES 290

PLATES, WITH EXPLANATIONS 301



CORRIGENDA

The indulgent student will please notice the following for the new edition North American Slime Moulds—

On p. 63, No. 17, read Physarum megalosporum Macbr. Last line should read 1917 Physarum melanospermum Sturgis, Mycologia, Vol. IX, p. 323.

On p. 67, last line but one, at the end, read, p. 323.

On p. 67, insert just before No. 23, Vicinity of Philadelphia,—Bilgram.

On p. 327, Plate XIII, lacks numbers. These may readily be supplied by consulting descriptive text.

On p. 344, in explanation figure 2, last word read hour.

On p. 346, for name of species read Fuligo rufa Pers., p. 28.



PREFACE TO THE FIRST EDITION[1]

The present work has grown out of a monograph entitled Myxomycetes of Eastern Iowa, published by the present author about eight years ago. The original work was intended chiefly for the use of the author's own pupils; but interest in the subject proved much wider than had been supposed, and a rather large edition of that little work was speedily exhausted. At that time literature on the subject in question—literature accessible to English readers—was scant indeed. Cooke's translation of Rostafinski, in so far as concerned the species of Great Britain, was practically all there was to be consulted in English.

In 1892 appeared in London Massee's Monograph of the Myxogastres, and two years later in the same world's centre the trustees of the British Museum brought out Lister's Mycetozoa. Although these two English works both claim revision of the entire group under discussion, the latter paying special attention to American forms, nevertheless there still seems place for a less pretentious volume which for American students shall present succinct descriptions of North American species only. The material basis of the present work consists of collections now in the herbarium of the State University of Iowa. In accumulating the material the author has had the generous assistance of botanists in all parts of the country, from Alaska to Panama, and the geographical distribution is in most cases authenticated by specimens from the localities named. The descriptions, in case of species represented in Europe, are based upon those of European authors; for forms first described in this country, the original descriptions have been consulted. A bibliography follows this preface.

In reference to the omnipresent vexed question of nomenclature, a word is perhaps necessary. De Candolle's rule, "The first authentic specific name published under the genus in which the species now stands," may be true philosophy, but it is certainly an open question how that rule shall be applied. If an author recognized and defined a given species in times past, and, in accordance with views then held, assigned the species to a particular genus, common honesty, it would seem, would require that his work be recognized. To assume that any later writer who may choose to set to familiar genera limits unknown before shall thereby be empowered to write all species so displaced his own, as if, forsooth, now for the first time in the history of science published or described, is not only absolutely and inexcusably misleading, but actually increases by just so much the amount of debris with which the taxonomy of the subject is already cumbered.

In face of a work so painstaking and voluminous as that of Rostafinski, and in view of the almost universal confusion that preceded him, it would seem idle to change for reasons purely technical the nomenclature which the Polish author has established. Especially is this true in the case of organisms so very perishable and fragile as those now in question where comparative revision is apt to result in uncertainty. We had preferred to leave the Rostafinskian, i. e. the heretofore current nomenclature, untouched; but since other writers have preferred to do otherwise, we are compelled to recognize the resultant confusion.

Slime-moulds have long attracted the attention of the student of nature. For nearly two hundred years they find place more or less definite in botanical literature. Micheli, 1729, figures a number of them, some so accurately that the identity of the species is hardly to be questioned. Other early writers are Buxbaum and Dillenius. But the great names before Rostafinski are Schrader, Persoon, and Fries. Schrader's judgment was especially clear. In his Nova Genera, 1797, he recognizes plainly the difference between slime-moulds and everything else that passed by the name of fungus, and proposed that they should be set off in a family by themselves,[2] but he suggested no definite name. Nees (C. G.) also made the same observation in 1817, and proposed the name Aerogastres; but he cites as type of his aerogastres, Eurotium, and includes so many fungi, that it seems unsafe now to approve his nomenclature. Schrader also has left an excellent account of the cribrarias, the basis of all that has since been attempted in that genus.

Persoon, in his Synopsis, 1801, attempts a review of all the fungi known up to that time. His notes and synonymy are invaluable, enabling us to understand the references of many of the earlier authors where these had otherwise been indefinite if not unintelligible. He makes a great many changes in nomenclature, and excuses himself on the ground that he follows, in this particular, illustrious examples! Unfortunately, so do we all!

Fries, in his Systema Mycologicum, 1829, summed up in most wonderful way the work of all his predecessors and the mycologic science of his time. In reading Fries the modern student hardly knows which most to admire, the author's far-reaching, patient research, the singular acumen of his taxonomic instinct, the graceful exactness of the Latin in which his conclusions are expressed, or the delicate courtesy with which he touches the work even the most primitive, of those his predecessors or contemporaries. Nevertheless in our particular group even the determinations of Fries are not conclusive. He himself often confesses as much. The microscopic technique of that day did not yield the data needful for minute comparison among these most delicate forms.

It remained for DeBary and Rostafinski to introduce a new factor into the description of species, and by spore-measurement and the delineation of microscopic detail to supply an element of definiteness which has no parallel in the work of any earlier student of this group. Under these conditions the revision undertaken by Rostafinski was of a most heroic sort. His work was almost a new beginning; and while in nomenclature he was inclined to follow the Paris Code, yet the inadequacy of the earlier descriptions often made such a course impracticable. The synonymy of Rostafinski is largely that of Fries, and upon this the Polish author attempts to apply the law of priority. In the historical note, wzmianka historyczna, accompanying the description of each specific form, he generally states the reason for the nomenclature he adopts, whether selected from the mass of supposed synonymy or introduced by himself de novo. Unfortunately, Rostafinski is sometimes purely arbitrary in his selections. He sometimes changes a specific or even generic name, otherwise correctly applied, simply because in primary etymological significance the name seems to him inappropriate. In such cases it is proper to restore the earlier name. Nevertheless Rostafinski is still our most trustworthy guide.

Of course, where later investigations have served to obliterate the once-thought patent distinctions between supposed genera or species, it is proper to unite such forms under the older determinable titles and this we have attempted. But wherever in the present work a name has been changed, the name of the earlier author will be found in parenthesis, followed immediately by that of him who made the change, and in general, recent practice, especially as expressed in the rules of the various codes, has determined the puzzling questions of nomenclature.

In justification of the use of Myxomycetes as a general title it may be said that in this case prevalent usage is not inconsistent with a rational application of the rules of priority. The Friesian designation Myxogastres was applied by its author in 1829 to the endosporous slime-moulds as a section of gasteromycetous fungi. Four years later Link, perceiving more clearly the absolute distinctness of the group, substituted the name Myxomycetes. In the same year Wallroth adopted the same designation, but strangely confused the limitations of the group he named. Wallroth seems to have thought Myxomycetes a synonym for Gasteromycetes Fries. In 1858 DeBary applied the title Mycetozoa to a group which included the then lately discovered Acrasieae with the true slime-moulds, both endosporous and exosporous. For all except the Acrasieae DeBary retained the old appellation, Myxomycetes. Rostafinski adopted DeBary's general name, but changed its application. As it has been shown, since DeBary's time, that the Acrasieae[3] have no true plasmodium, and are therefore not properly, or at least not necessarily, associated with the slime-moulds, there appears no necessity for the term Mycetozoa, and the question lies between Myxogastres and Myxomycetes. Of these two names the former, as we have seen, has undoubted priority, but only as applied to the endosporous species. The same thing was true of Link's designation until DeBary redefined it, but having been taken up by DeBary, redefined and correctly applied, Myxomycetes (Link) DeBary must remain the undisputed title for all true slime-moulds, endosporous and exosporous alike.

In arranging the larger divisions of the group the scheme of Rostafinski has been somewhat modified in order to give expression to what the present author deems a more natural sequence of species. The highest expression of myxomycetan fructification is doubtless the isolated sporangium with its capillitium. This is reached by successive differentiations from the simple plasmodium. The aethalium may be esteemed in some instances a case of degeneration, in others of arrested development. In any event in the present arrangement, aethalioid forms are first disposed of, leaving the sporangiate species to follow from plasmodiocarpous as directly as may be.

The artificial keys herewith presented proceed on the same plan and are to be taken, as such keys always are, not as definitive in any case, but simply as an aid to help the student more speedily to reach a probably satisfactory description.

FOOTNOTES:

[1] The North American Slime Moulds, 1899.

[2] Schrader, Nova Plantarum Genera, 1797, pp. vi-vii.

[3] Cf. Edgar W. Olive, Monograph of the Acrasieae; Boston, 1902.



PREFACE TO THE SECOND EDITION

The first edition of this little book having been exhausted long ago, the writer in this second issue takes opportunity to correct sundry errata, typographical and other, and at the same time to incorporate such new information in reference to individual species and to the subject entire as the researches of more recent years may afford.

To Miss Gulielma Lister, of London, the writer expresses his sense of deep obligation for much assistance in settling difficult matters of nomenclature and identification; it will be found as a result that in most instances the same thing in the two volumes, English and American, appears under the same name. There are still differences; these result in most cases from different points of view, different estimates or emphasis of characteristics in these ever elusive objects.

To Professor Torrend, formerly of Lisbon, the writer is indebted for a set of European types, and to Professor Bethel, pathologist of Denver, for rich material from the fertile mountains of Colorado and California. To Professor Morton Peck, of Oregon, we are indebted for many notes of the color of plasmodia and for collections of Pacific coast forms. Mr. Bilgram, of Philadelphia, read the manuscript of the genus Physarum and has contributed many rare species. To Dr. Sturgis, of Massachusetts, we are indebted for material from both east and west.

The present volume is intended especially for American readers and is accordingly particularly devoted to a discussion of species so far reported on the western continent; nevertheless it has seemed wise to include a brief description of some other forms as well, and reference to many extra-limital species now generally recognized will be found here and there in connection with the more extended treatment of related American forms.

February twenty-eight, 1921.

At the last moment, nearly all plates and drawings of the first edition disappeared! necessitating a quick renewal of drawings and plates. This may in part explain lack of uniformity, and various minor irregularities sure to grieve the intelligent student.



BIBLIOGRAPHY

The following are the principal works consulted in the prosecution of the investigations here recorded:—

1763. Adanson, M. Familles des Plantes.

1805. Albertini—see under Schweinitz.

1841. Annals and Magazine of Natural History. London, various volumes: 1841, Ser. I., vol. vi.; 1850, Ser. II., vol. v.

1887. Annals of Botany, vols. i-xxxi.

1783. Batsch, A. J. G. C. Elenchus Fungorum; with Continuatio I. 1786; Continuatio II. 1789.

1775. Battara, A. Fungorum Agri Arimensis Historia.

1860. Berkeley, M. J. Outlines of Fungology.

1789. Bolton, J. History of Funguses about Halifax.

1851. Bonorden, H. F. Mycologie.

1875. Botanical Gazette, The. Various volumes to 1921.

1843. Botanische Zeitung. Various volumes to 1898.

1892. Bulletin Laboratories Nat. Hist. Iowa, vol. ii.

1873. Bulletin Torrey Botanical Club. Various volumes to 1898.

1791. Bulliard, P. Histoire des Champignons de la France.

1721. Buxbaum, J. C. Enumeratio Plantarum.

1863. Cienkowski, L. Zur Entwickelungsgeschichte der Myxomyceten.

1893. Celakowsky, L. Die Myxomyceten Boehmens.

1871. Cooke, M. C. Handbook of British Fungi.

1877. Cooke, M. C. Myxomycetes of Great Britain.

1877. Cooke, M. C. Myxomycetes of the United States.

1837. Corda, A. I. C. Icones Fungorum.

1854. Currey, F., in Quart. Journal Microscopical Science.

1848. Curtis, M. A. Contributions to the Mycology of North America; Am. Journal of Science and Arts.

1859. De Bary, A. H. Die Mycetozoen.

1866. De Bary, A. H. Morphologie der Pilze, Mycetozoen und Bacterien.

1802. De Candolle, A. P. Flore Francaise.

1719. Dillenius, J. J. Catalogus Plantarum circa Cissam nascentium.

1813. Ditmar, L. P. F., Sturm, Deutschlands Flora, 3te Abtheil; Die Pilze Deutschlands.

1878. Ellis, J. B. North American Fungi. Exsiccati. et seq.

1818. Ehrenberg, C. G. Sylvae Mycologicae Berolinenses.

1761. Flora, Danica, vol. i.; also vols. iii. iv. v.

1817. Fries, Elias M. Symbolae Gasteromycetum.

1818. Fries, Elias M. Observationes Mycologicae.

1829. Fries, Elias M. Systema Mycologicum.

1873. Fuckel, I. Symbolae Mycologicae.

1791. Gmelin, C. C. Systema Naturae, Tom. II., Pars. ii.

1823. Greville, R. K. Scottish Cryptogamic Flora.

1872. Grevillea, various volumes to 1897.

1751. Hill, Sir John. A History of Plants.

1795. Hoffman, G. C. Deutschlands Flora.

1773. Jacquin, N. I. Miscellanea Austriaca.

1885. Journal of Mycology and seq.

1878. Karsten, Mycologia Fennica.

1809. Link, H. F. Nova Plantarum Genera.

1753. Linne, C. Systema Naturae—to 1767.

1894. Lister, Arthur. The Mycetozoa; 1911, Second Edition, revised by Gulielma Lister.

1892. Massee, George. Monograph of the Myxogastres.

1729. Micheli, P. A. Nova Plantarum Genera.

1892. Morgan, A. P. Myxomycetes of the Miami Valley—to 1895.

1816. Nees, Ch. G. D. Das System der Pilze und Schwamme.

1837. Nees, T. F. L. et A. Henry. Das System der Pilze.

1869. Peck, Charles H. Reports N. Y. State Museum Nat. History—to 1898.

1795. Persoon, C. H. Observationes Mycologicae, Pars prima.

1799. Persoon, C. H. Observationes Mycologicae, Pars secunda.

1797. Persoon, C. H. Tentamen Dispositionis Methodicae Fungorum.

1801. Persoon, C. H. Synopsis Methodica Fungorum.

1844. Rabenhorst, L. Deutschland's Kryptogamenflora.

1884. Raciborski, M. Myxomycetes Agri Krakov. Genera, Species et Varietates novae.

1888. Raunkiaer, C. Myxomycetes Daniae.

1769. Retzius, A. J. In Handlungen, Kon. Svensk. Vet. Acad.

1890. Rex, George A. In Proceedings Philad. Acad. of Nat. Sciences—to 1893.

1873. Rostafinski, J. Versuch eines Systems der Mycetozoen.

1875. Rostafinski, J. Sluzowce Monografia.

1778. Roth, A. W. Tentamen Florae Germanicae.

1888. Saccardo, P. A. Sylloge Fungorum, vol. vii., et seq.

1841. Sauter, A. Flora, vol. xxiv., p. 316.

1762. Schaeffer, J. C. Fungi qui in Bav. et Pal. nascuntur—to 1774.

1797. Schrader, H. A. Nova Genera Plantarum.

1890. Schroeter, J. Myxomycetes, in Engler u. Prantl Pflanzenfamilien.

1885. Schroeter, J. Kryptogamenflora von Schlesien, die Pilze.

1801. Schumacher, C. F. Enumeratio Plant. Saell. crescentium.

1805. Albertini, I. and Schweinitz, L. D. de. Conspectus Fungorum.

1822. Schweinitz, L. D. de. Synopsis Fungorum Car. Sup.

1834. Schweinitz, L. D. de. Synopsis Fungorum in America Boreali.

1797. Sowerby, J. English Fungi—to 1809; 3 vols.

1760. Scopoli, J. A. Flora Carniolica—to 1772.

1797. Trentepohl, K. Observations Botanicae,—to Roth, Catalecta Botanica, Fasc. i.

1833. Wallroth, C. F. Flora Cryptogamica Germaniae.

1787. Willdenow, K. L. Florae Berolinensis Prodromus.

1886. Wingate, Harold, Jour. Mycol. ii., 125.

1889. Wingate Harold, In Proc. Acad. Nat. Sci. Philad.

1890. Wingate, Harold—in Revue Mycologique.

1873. Woronin u. Famintzin, Ueber Zwei neuen Formen von Schleimpilzen.

1885. Zopf, W. Die Pilzthiere oder Schleimpilze.

To these may be added the many contributions on the general subject, as these are found in all sorts of current botanical literature; cited everywhere in this volume as occasion offered.



INTRODUCTORY

The Myxomycetes, or slime-moulds, include certain very delicate and extremely beautiful fungus-like organisms common in all the moist and wooded regions of the earth. Deriving sustenance, as they for the most part do, in connection with the decomposition of organic matter, they are usually to be found upon or near decaying logs, sticks, leaves, and other masses of vegetable detritus, wherever the quantity of such material is sufficient to insure continuous moisture. In fruit, however, as will appear hereafter, slime-moulds may occur on objects of any and every sort. Their minuteness retires them from ordinary ken; but such is the extreme beauty of their microscopic structure, such the exceeding interest of their life-history, that for many years enthusiastic students have found the group one of peculiar fascination, in some respects, at least, the most interesting and remarkable that falls beneath our lens.

The slime-mould presents in the course of its life-history two very distinct phases: the vegetative, or growing, assimilating phase, and the reproductive. The former is in many cases inconspicuous and therefore unobserved; the latter generally receives more or less attention at the hands of the collector of fungi. The vegetative phase differs from the corresponding phase of all other plants in that it exhibits extreme simplicity of structure, if structure that may be called which consists of a simple mass of protoplasm destitute of cell-walls, protean in form and amoeboid in its movements. This phase of the slime-mould is described as plasmodial and it is proper to designate the vegetative phase in any species, as the plasmodium of the species. It was formerly taught that the plasmodium is unicellular, but more recent investigation has shown that the plasmodial protoplasm is not only multinuclear but karyokinetic; its cells divide and redivide, as do the reproductive cells of plants and animals generally. Nevertheless, in its plasmodial phase, the slime-mould is hardly to be distinguished from any other protoplasmic mass, may be compared to a giant amoeba, and justifies in so far the views of those systematists who would remove the slime-moulds from the domain of the botanist altogether, and call them animals. The plasmodium is often quite large. It may frequently be found covering with manifold ramifications and net-like sheets the surface of some convenient substratum for the space of several square feet.

The substance of the plasmodium has about the consistency of the white of an egg; is slippery to the touch, tasteless, and odorless. Plasmodia vary in color in different species and at different times in the same species. The prevailing color is yellow, but may be brown, orange, red, ruby-red, violet, in fact any tint, even green. Young plasmodia in certain species are colorless (as in Diderma floriforme), while many have a peculiar ecru-white or creamy tint difficult to define. Not only does the color change, sometimes more than once in the course of the life history of the same species, but it may be the same for several forms, which in fruit are singularly diverse indeed, so that the mere color of the plasmodium brings small assistance to the systematist. In fact, the color depends no doubt upon the presence in the plasmodium of various matters, more or less foreign, unassimilated, possibly some of them excretory, differing from day to day.

In its plasmodial state, as has been said, the slime-mould affects damp or moist situations, and during warm weather in such places spreads over all moist surfaces, creeps through the interstices of the rotting bark, spreads between the cells, between the growth-layers of the wood, runs in corded vein-like nets between the wood and bark, and finds in all these cases nutrition in the products of organic decomposition. Such a plasmodium may be divided, and so long as suitable surroundings are maintained, each part will manifest all the properties of the whole. Parts of the same plasmodium will even coalesce again. If a piece of plasmodium-bearing wood be brought indoors, be protected from desiccation by aid of a moist dark chamber, not too warm (70 deg. F.), the organism seems to suffer little if any injury, but will continue for days or weeks to manifest all the phenomena of living matter. Thus, under such circumstances, the plasmodium will constantly change shape and position, can be induced to spread over a plate of moist glass, and so be transferred to the stage of a microscope, there to exhibit in the richest and most interesting and abundant fashion the streaming protoplasmic currents. As just indicated, the plasmodia follow moisture, creep from one moist substance to another, especially follow nutritive substrata. They seem also to secure in some way exclusive possession. I have never seen them interfered with by hyphae or enemies of any sort, nor do they seem to interfere with one another. Plasmodia of two common species, Hemitrichia clavata and H. vesparium are often side by side on the same substratum, but do not mix, and their perfected fruits presently stand erect side by side, each with its own characteristics, entirely unaffected by the presence of the other. On the other hand, it is probable that some of the forms which, judged by their different fructifications, and by this alone, are to us distinct, may be more closely related than we suspect, and puzzling phases which show the distinctive marks supposed to characterize different species are no doubt sometimes to be explained on the theory of plasmodial crossing; they are hybrids.

Under certain conditions, low temperature, lack of moisture, the plasmodium may pass into a resting phase, when it masses itself in heaps and may become quite dry in lumps of considerable size, and so await the return of favorable conditions when former activity is quickly resumed. Sometimes the larger plasmodia pass into the resting phase by undergoing a very peculiar change of structure. In ordinary circumstances the abundant free nuclei demonstrable in the plasmodium afford the only evidence of cellular organization. In passing now into the condition of rest, the whole protoplasmic mass separates simultaneously into numerous definite polyhedral or parenchymatous cells, each with a well-developed cellulose wall.[4] When the conditions essential to activity are restored, the walls disappear, the cellulose is resorbed, and the plasmodium resumes its usual habit and structure.

The plasmodial phase of the slime-mould, like the hyphal phase of the fungus, may continue a long time; for months, possibly for years. The reason for making the latter statement will presently appear. But however long or short the plasmodial phase continue, the time of fruit, the reproductive phase, at length arrives. When this time comes, induced partly by a certain maturity in the organism itself, partly no doubt by the trend of external conditions, the plasmodium no longer as before evades the light, but pushes to the surface, and appears usually in some elevated or exposed position, the upper side of the log, the top of the stump, the upper surface of its habitat, whatever that may be; or even leaves its nutrient base entirely and finds lodging on some neighboring object. In such emergency the stems and leaves of flowering plants are often made to serve, and even fruits and flowers afford convenient resting places. The object now to be attained is not the formation of fruit alone, but likewise its speedy desiccation and the prompt dispersal of the perfected spores. Nothing can be more interesting than to watch the slime-mould as its plasmodium accomplishes this its last migration. If hitherto its habitat has been the soft interior of a rotten log, it now begins to ooze out in all directions, to well up through the crevices of the bark as if pushed by some energy acting in the rear, to stream down upon the ground, to flow in a hundred tiny streams over all the region round about, to climb all stems, ascend all branches, to the height of many inches, all to pass suddenly as if by magic charm into one widespread, dusty field of flying spores. Or, to be more exact, whatever the position ultimately assumed, the plasmodium soon becomes quiescent, takes on definite and ultimate shape, which varies greatly, almost for each species. Thus it may simply form a flat, cake-like mass, aethalium, internally divided into an indefinite number of ill-defined spore cases, sporangia; or the plasmodium may take the form of a simple net, plasmodiocarp, whose cords stand out like swollen veins, whose meshes vary both in form and size; or more commonly the whole protoplasmic mass breaks up into little spheroidal heaps which may be sessile directly on the substratum, or may be lifted on tiny stems, stipitate, which may rest in turn upon a common sheet-like film, or more or less continuous net, spreading beneath them all, the hypothallus. In any case, each differentiated portion of the plasmodium, portion poorly or well defined, elongate, net-like, spheroidal, elliptical, or of whatever shape, becomes at length a sporangium, spore-case, receptacle for the development and temporary preservation of the spores.[5]

The slime-moulds were formerly classed with the gasteromycetous fungi, puff-balls, and in description of their fruiting phase the terms applicable to the description of a puff-ball are still employed, although it will be understood that the structures described are not in the two cases homologous; analogous only. The sporangium of the slime-mould exhibits usually a distinct peridium, or outer limiting wall, which is at first continuous, enclosing the spores and their attendant machinery, but at length ruptures, irregularly as a rule, and so suffers the contents to escape. The peridium may be double, varies in texture, color, persistence, and so forth, as will be more fully set forth in the several specific descriptions. The peridium blends with the hypothallus below when such structure is recognizable, either directly, when the sporangium is sessile, or by the intervention of a stipe. The stipe may be hollow, may contain coloring matter of some sort, or may even contain peculiar spore-like cells or spores; is often furrowed, and in some cases shows a disposition to unite or blend with the stalks of neighboring sporangia. In many cases the stipe is continued upward, more or less definitely into the cavity of the sporangium, and there forms the columella, sometimes simple and rounded, like the analogous structure in the Mucores, sometimes as in Comatricha, branching again and again in wonderful richness and complexity.

Each sporangium is at maturity filled with numerous unicellular spores. These are usually spherical, sometimes flattened at various points by mutual contact; they are of various colors, more commonly yellow or violet brown, are sometimes smooth (?), but generally roughened either by the presence of minute warts, or spines, or by the occurence of more or less strongly elevated bands dividing reticulately the entire surface. The spores are in all cases small 3-20 mu, and reveal their surface characters only under the most excellent lenses.

Associated with the spores in the sporangium occurs the capillitium. This consists of most delicate thread-or hair-like elements, offering great variety both in form and structure. The threads composing the capillitium are not to be regarded, even when free, as cells, nor even of cellular origin; probably, as would appear from the researches of Strasburger and Harper, all forms of capillitial threads arise in connection with vacuoles in the protoplasmic mass. "Whether the thread is hollow or solid, simple or branched, free or connected with the peridium or a columella,—these are entirely secondary conditions, depending on the extent and form of the vacuoles."[6] They may occur singly or be combined into a net, they may be terete or flat, attached to the peridial wall or free, simple or adorned with bands or spires and knobs in every variety, uniform or profusely knotted and thickened at intervals, and burdened with calcic particles. In many cases, the capillitium contributes materially to the dispersal of the spores; in others, it doubtless contributes mechanically to the support of the peridial wall, and renders so far persistent the delicate sporangium. For more exact description the reader is again referred to the specific delineations which follow.

The transition from phase to phase requires, as intimated, no great length of time. Tilmadoche polycephala completed the transition from vegetative to fruiting phase in less than twelve hours.

The germination of the spores ensues closely upon their dispersal or maturity and is unique in many respects.[7] The wall of the spore is ruptured and the protoplasmic content escapes as a zoospore indistinguishable so far from an amoeba, or from the zoospore of our chytridiaceous fungi. This amoeboid zoospore is without cell-wall, changes its outline, and moves slowly by creeping or flowing from point to point. At this stage many of the spores assume each a flagellate cilium, and so acquire power of more rapid locomotion. The zoospores, whether ciliate or not, thus enjoy independent existence and are capable of continuing such existence for some time, assimilating, growing, and even reproducing themselves by simple fission, over and over again. This takes place, of course, only in the presence of suitable nutrient media.

Nevertheless the spores of many species germinate quickly simply in water, and a drop suspended in the form of the ordinary drop-culture on a cover-glass affords ample opportunity. In the course of time, usually not more than two or three days, the swarm spores cease their activity, lose their cilia, and come to rest, exhibiting at most nothing more than the slow amoeboid movement already referred to. In the course of two or three days more, in favorable cases, the little spores begin to assemble and flow together; at first into small aggregations, then larger, until at length all have blended in one creeping protoplasmic mass to form thus once again the plasmodium, or plasmodial phase with which the round began. Small plasmodia may generally be thus obtained artificially from drop-cultures. Such, however, in the experience of the writer, are with difficulty kept alive. Hay infusions, infusions of rotten wood, etc., may sometimes for a time give excellent results.

The spores of Didymium crustaceum were sown upon a heap of leaves in autumn. An abundant display of the same species followed in the next June; but, of course, the intervening phases were not observed. The most satisfactory studies are obtained by plasmodia carefully brought in directly from the field. A plasmodium that appeared suddenly and passed to fruit on agar in a petri dish offers a valuable suggestion for further research.

With such a life-history as that thus briefly sketched, it is small wonder that the taxonomic place of the slime-moulds is a matter of uncertainty, not to say perplexity. So long as men studied the ripened fruit, the sporangia and the spores, with the marvellous capillitium, there seemed little difficulty; the myxomycetes were fungi, related to the puff-balls, and in fact to be classed in the same natural order. The synonymy of some of the more noticeable species affords a very interesting epitome of the history of scientific thought in this particular field of investigation. Thus the first described slime-mould identifiable by its description is Lycogala epidendrum (Buxbaum) Fries, the most puff-ball looking of the whole series. Ray, in 1690, called this Fungus coccineus. In 1718, Ruppinus described the same thing as Lycoperdon sanguineum; Dillenius at about the same time, as Bovista miniata; and it was not until 1729, that Micheli so far appreciated the structure of the little puff-ball as to give it a definite, independent, generic place and title, Lycogala globosum ..., etc.[8]

But Micheli's light was too strong for his generation. As Fries, one hundred years later quaintly says, ... "immortalis Micheli tam claram lucem accendit ut succesores proximi eam ne ferre quidem potuerint." Notwithstanding Micheli's clear distinctions, he was entirely disregarded, and our little Lycogala was dubbed Lycoperdon and Mucor down to the end of the century; and so it was not till 1790 that Persoon comes around to the standpoint of Micheli and writes Lycogala miniata. Fries himself, reviewing the labors of his predecessors all, grouped the slime-moulds as a sub-order of the gasteromycetes and gave expression to his view of their nature and position when he named the sub-order Myxogastres. In 1833, Link, having more prominently in mind the minuteness of most of the species collocated by Fries, and perceiving perhaps more clearly even than the great mycologist the entire independence of the group, suggested as a substitute for the sub-order Myxogastres, the order Myxomycetes, slime-moulds. Link's decision passed unchallenged for nearly thirty years. The slime-moulds were set apart by themselves; they were fungi without question and, of course, plants.

If the hypha is the morphological test of a fungus, then it is plain that the slime-moulds are not fungi. No myxomycete has hyphae, nor indeed anything at all of the kind. Nevertheless, there are certain parasitic fungi, Chytridiaceae for example, whose relationships plainly entitle them to a place among the hyphate forms that have no hyphae whatever in the entire round of their life-history. These are, however, exceptional cases and really do not bear very closely on the question at issue.

Physiologically, the fungi are incapable of independent existence, being destitute of chlorophyl. In this respect the slime-moulds are like the fungi; they are nearly all saprophytes and absolutely destitute of chlorophyl. Unfortunately this physiological character is identically that one which the fungi share with the whole animal world, so that the startling inquiry instantly rises, are the slime-moulds plants at all? Are they not animals? Do not their amoeboid spores and plasmodia ally them at once to the amoeba and his congeners, to all the monad, rhizopodal world? This is the position suggested by DeBary in 1858, and adopted since by many distinguished authorities, among whom may be mentioned Saville Kent, of England, and Dr. William Zopf, of Germany, in Die Pilzthiere, 1885. Rostafinski was a pupil of DeBary's. However, his volume on the slime-moulds was written after leaving the laboratory; and no doubt with the suggestion of his master still before his mind, he adopts the title Mycetozoa, as indicating a closer relationship with the animal world, but our leading authority really has little to say in regard to the matter.[9]

Dr. Schroeter, a recent writer on the subject, after showing the probable connection between the phycochromaceous Algae and the simplest colorless forms, namely, the Schizomycetes, goes on to remark: "At the same point where the Schizomycetous series take rise, there begin certain other lines of development among the most diminutive protoplasmic masses.... Through the amoebae one of these lines gives rise on the one hand to rhizopods and sponges in the animal kingdom, on the other to the Myxomycetes among the fungi." This ranges the Myxomycetes, in origin at least, near the Schizomycetes.

The brilliant studies of Dr. Thaxter, resulting in the discovery and recognition of a new group, a new order of the schizomycetes, strikingly confirm the judgment of Schroeter.[10] Here we have forms that strangely unite characteristics of both the groups in question. If on the one hand the Myxobacteria are certainly schizomycetes, on the other they just as certainly offer in their developmental history "phenomena closely resembling those presented by plasmodia or pseudo-plasmodia...." Now the schizophytes certainly pass by gradations easy to the filamentous algae, and so to relationship with the plants, and the discovery of the Myxobacteriacae, brings the myxomycetes very near the vegetable kingdom if not within it.

All authorities agree that the myxomycetes have no connection in the direction of upward development, "keinen Anschluss nach oben," if then their only relationship with other organisms is to be found at the bottom (centre) of the series only, it is purely a matter of indifference whether we say plant or animal, for at the only point where there is connection there is no distinction.

But why call them either animals or plants? Was Nature then so poor that forsooth only two lines of differentiation were at the beginning open for her effort? May we not rather believe that life's tree may have risen at first in hundreds of tentative trunks of which two have become in the progress of the ages so far dominant as to entirely obscure less progressive types? The Myxomycetes are independent; all that we may attempt is to assert their near kinship with one or other of life's great branches.

The cellulose of the slime-mould looks toward the world of plants. The aerial fructification and stipitate habit of the higher forms tends in the same direction. The disposition to attach themselves to some fixed base is a curious characteristic of plants, more pronounced as we ascend the scale; but by no means lacking in many of the simplest, diatoms, filamentous algae, etc., and it is quite as reasonable to call a vorticella, or a stentor, by virtue of his stipitate form and habit, a plant as to call a slime-mould an animal because in one stage of its history it resembles an amoeba. The total life of an organism in any case must be taken into account.[11] At the outset plants and animals are alike; there is no doubt about it; they differ in the course of their life-histories. The plasmodium is the vegetative phase of the slime-mould. It needs no cell-walls of cellulose, no more than do the dividing cells of a lily-endosperm; both are nourished by organic food and resort to walls only as conditions change. The possession of walls is an indication of some maturity. In the slime-mould the assumption of walls is indeed delayed. Walls at length appear and when they do come they are like those of the lily; they are cellulose. The myxomycetes may be regarded as a section of the organic world in which the forces of heredity are at a maximum whatever those forces may be. Slime-moulds have in smallest degree responded to the stimulus of environment. They have, it is true, escaped the sea, the fresh waters in part, and become adapted to habitation on dry land, but nothing more. It is instructive to reflect that even in her most highly differentiated forms the channel which Nature elects for the transmissal of all that heredity may bestow, is naught else than a minute mass of naked protoplasm. Nature reverts, we say, to her most ancient and simple phases, and heredity is still consonant with apparent simplicity; apparent we say, for as becomes increasingly evident, nothing that lives is simple!

The fact is the Myxomycetes constitute an exceedingly well-defined group, and the question of relationship in any direction need not much perplex the student. Least of all is the question to be settled by anybody's dictum, which is apt to be positive inversely in proportion to the speaker's acquaintance with the subject. No one test can be applied as a universal touchstone to separate plants from animals. Such is simply petitio principii. Nor is there any advantage at present apparent in attempts to associate slime-moulds with other presumably related groups. Saville Kent's effort to join them with the sponges was not happy, and Dr. Zopf's association of the slime-moulds and monads appears forced, at best; for when it comes to the consideration of the former, their systematic and even morphological treatment, he is compelled to deal with them by themselves under headings such as "Eumycetozoen," "Hoehere Pilzthiere," etc. One rather commends the discreetness of DeBary, whose painstaking investigations first called attention to the uncertain position of the group. After reviewing the results of all his labors DeBary does not quite relegate the slime-moulds to the zoologist for further consideration, but simply says:[12] "From naked amoeba, with which the Mycetozoa (=Myxomycetes) are connected in ascending line, the zoologists with reason derive the copiously and highly developed section of the shell-forming Rhizopoda.... And since there are sufficient grounds for placing the rhizopods outside the vegetable and in the animal kingdom, and this is undoubtedly the true position for the amoebae, which are their earlier and simpler forms, the Mycetozoa, which may be directly derived from the same stem, are at least brought very near to the domain of zoology."

Notwithstanding all the controversy in regard to the matter, the study of the slime-moulds still rests chiefly with the botanists. A simple phylogenetic scheme for thallophytes is offered in the Strasburger text as follows:—

THALLOPHYTA

1. SCHIZOPHYTA BACTERIA CYANOPHYCEAE

2. FLAGELLATA { MYXOMYCETES { PERIDINEAE a { CONJUGATAE { HETEROCONTAE

{ CHLOROPHYCEAE b { CHARACEAE

3. RHODOPHYCEAE

4. FUNGI

About 500 species of slime-moulds have been described. Saccardo enumerates 443, inclusive of those denominated doubtful or less perfectly known. These 443 species are distributed among 47 genera, of which 15 are represented by but a single species each,—monotypic. In the United States there have been recognized about 300 species. Of those here described, some are almost world-wide in their distribution, others are limited to comparatively narrow boundaries. The greater number occur in the temperate regions of the earth, although many are reported from the tropics, and some even from the arctic zone. Schroeter found Physarum cinereum at North Cape. Our Iowa forms are much more numerous in the eastern, that is, the wooded regions of the state. Physarum cinereum has however been taken on the untouched prairie, and on the western deserts, as also Physarum contextum on the decaying stem of Calamagrostis, far from forest.

As to the economic importance of our myxomycetes, there is no long chapter to write. Fries says: "Usu in vita communi parum admodum sese commendant, sed in oeconomia naturae certe non spernendi. Multa insectorum genera ex eorum sporidiis unica capiunt nutrimenta." However this may be, there is one species which has come to light since Fries's day which is the source of no inconsiderable mischief to the agriculturist. Plasmodiophora brassicae occasions the disease known as "club-root" in cabbage, and has been often made the subject of discussion in our agricultural and botanical journals.[13] Aside from the injurious tendencies, possible or real, of the forms mentioned, I know not that all other slime-moulds of all the world, taken all together, affect in any slightest measure the hap or fortune of man or nation. And yet, if in the economic relations of things, man's intellectual life is to be considered, then surely come the uncertain myxos, with their fascinating problems proffered still in forms of unapproachable delicacy and beauty, not without inspiration.

COLLECTION AND CARE OF SLIME-MOULD MATERIAL

On this subject a word may here be appropriate. As just now intimated, specimens may be taken at the appropriate season in almost any or every locality. Beginning with the latter part of May or first of June, in the Northern states, plasmodia are to be found everywhere on piles of organic refuse: in the woods, especially about fallen and rotting logs, undisturbed piles of leaves, beds of moss, stumps, by the seeping edge of melting snow on mountain sides, by sedgy drain or swamp, nor less in the open field where piles of straw or herbaceous matter of any sort sinks in undisturbed decay. Within fifty years tree-planting in all the prairie states has greatly extended the range of many more definitely woodland species, so that species of Stemonitis, for instance, are common in the groves on farms far into Nebraska and Dakota. In any locality the plasmodia pass rapidly to fruit, but not infrequently a plasmodium in June will be succeeded in the same place by others of the same species, on and on, until the cold of approaching winter checks all vital phenomena. The process of fruiting should be watched as far as possible, and for herbarium material, allowed to pass to perfection in the field.

Specimens collected should be placed immediately in boxes in such a way as to suffer no injury in transport; beautiful material is often ruined by lack of care on the part of the collector. Once at the herbarium, specimens may be mounted by gluing the supporting material to the bottom of a small box. Boxes of uniform size and depth may be secured for the purpose. Some collectors prefer to fasten the specimen to a piece of stiff paper, of a size to be pressed into the box snugly, but which may be removed at pleasure. Every pains must in any case be taken to exclude insects. Against such depredators occasional baking of the boxes on the steam radiator in winter is found to be an efficient remedy.

For simple microscopic examination it will be found convenient to first wet the material with alcohol on the slide, then with a weak solution of potassic hydrate, to cause the spores and other structures to assume proper plumpness. A little glycerine may be added or run under the cover if it is desired to preserve the material for further or prolonged study. For permanent mounting nothing in most cases is better than glycerine jelly. As a preparation, the material should lie for some time in Haentsch's fluid,[14] opportunity being given for evaporation of the alcohol and water. When the material shows the proper clearness and fulness, it may be mounted in jelly in the usual way. Kaiser's formula gives beautiful results. After mounting, the preparation should be sealed with some good cement, as Hollis's glue.

FOOTNOTES:

[4] DeBary, Morphology and Biology of the Fungi, p. 428.

[5] See, however, Ceratiomyxa, p. 18, following.

[6] Harper in Botanical Gazette, Vol. XXX., p. 219.

[7] The following germination periods are furnished by Dr. Constantineanu (Inaugural Dissertation ueber die Entwickelungsbedingungen der Myxomyceten; Halle, 1907).

Reticularia lycoperdon 30 to 60 min. Fuligo ovata 30 to 90 min. Stemonitis splendens 5 to 6 hrs. Perichaena depressa 5 to 8 hrs. Amaurochaete atra 6 to 10 hrs. Arcyria incarnata 8 to 10 hrs. Lycogala epidendrum to 60 hrs. Physarum didermoides 1 to 10 da. Dictydium cancellatum 1 to 20 da.

These records are for sowings in drop cultures, in distilled water, kept at temperature of 65 deg.-70 deg. F. (18 deg.-20 deg. C.).

Our own experiments have been made both with distilled water and tap-water with the advantage in favor of the latter. Dictydium cancellatum germinates in tap-water at temperature 70 deg.-80 deg. F. in 12-15 hours fresh from the field. Fuligo ovata spores were all swarming in about one hour at the same temperature. Jahn (Myxomycetenstudien; Ber. der Deutschen Bot. Ges. Bd. XXIII., p. 495) finds that the germination in some cases as Stemonitis species, is hastened by wetting, then drying, then wetting again.

Pinoy thinks microbes aid in germination (Bull. Soc. Myc. de France T. XVIII.).

[8] The plasmodium in this case chances to be red, scarlet, etc.

[9] "Die Myxomyceten sind ebenso den Pilzen wie den echten Thieren verwandt."—Rostafinski; closing sentence of the Versuch, thesis for his doctorate at the University of Strasburg, 1873.

[10] Botanical Gazette, XVII., pp. 389, etc.; 1892.

[11] Researches of Olive, Trans. Wis. Acad. Sci., Arts and Let., XV., Pt. 2, p. 771, and of Jahn, Ber. d. Deutsch Bot. Ges. XXVI., p. 342, and XXIX., p. 231, demonstrate synapsis, and accordingly some form of alternation among the slime-moulds. From the protracted and painstaking investigation of the German author it appears that in Didymium at least, and probably Badhamia synapsis immediately precedes spore-formation as in Ceratiomyxa; that the amoeboid issue of the spores are haploid; the nuclei of the plasmodium, diploid; that the ordinary vegetative plasmodium is accordingly sporophytic. That is, the sporophytic phase is dominant, as in higher plants.

[12] Cf., 1884, Ver. Morph. u. Biol. der Pilz. Mycet. u. Bact., p. 478. Italics, in quotations, ours.

[13] See Journal of Mycology, Washington, D. C., Vol. VII., No. 2; also Bulletin No. 66, Agric. Station of Vermont. See also Bull. 33 Arizona Agric. Ex. Station: An Inquiry into the Cause and Nature of Crown-Gall. J. W. Tuomey. Also Bull. Torrey Bot. Club, Vol. 21, p. 26, where it appears that club-root may attack crucifers generally.

Professor B. M. Duggar in Fungous Diseases of Plants, pp. 97-102, gives to club-root an illustrated chapter.

[14]

Haentsch's Fluid:— Alcohol 90% three parts Water two parts Glycerine one part



THE NORTH AMERICAN SLIME-MOULDS

THE MYXOMYCETES (Link) DeBary

Chlorophyl-less organisms whose vegetative phase consists of a naked mass of multinuclear protoplasm, the plasmodium; reproduced by spores which are either free or more commonly enclosed in sporangia, and which on germinating produce ciliated or amoeboid zoospores, whose coalescence gives rise to the plasmodium.

The Myxomycetes are,—

A. Parasites, in the cells of living plants PHYTOMYXINAE

B. Saprophytes, developed in connection with decaying vegetable matter:

a. With free spores EXOSPOREAE

b. With spores in receptacles or sporangia MYXOGASTRES

Sub-Class PHYTOMYXINAE Schroeter

1889. Phytomyxinae Schroeter, Engl. u. Prantl., I., i., pp. 1 and 5.

The parasitic Myxomycetes affecting plants include but few (four or five) species, distributed among four genera. All are parasites in the cells of particular hosts; their vegetative phase is plasmodial and their spores are formed by the simultaneous breaking up of the plasmodium into an indefinite number of independent cells. But a single genus need here concern us,—

Plasmodiophora Woronin

1879. Plasmodiophora Woronin, Pringsh. Jahrb., XI., p. 548.

Parasitic in the parenchymatous cells of the roots of living plants, causing noticeable enlargement of the affected organ, producing at length galls, knots, and various deformities and distortions. Spores spherical, smooth, colorless, 16 mu.

I. PLASMODIOPHORA BRASSICAE Woronin.

1879. Plasmodiophora brassicae Woronin, op. cit.

This species, typical of forms so far reported in this country, infests the roots of cabbages,[15] and produces a very serious disease of that vegetable. In England the malady has long been known under the names "clubbing," "fingers and toes," etc. The roots affected swell greatly, and at length resemble sometimes the flexed fingers of the human hand; hence the English name. As the disease progresses, the roots speedily rot away, to the serious injury of the leaf-bearing portion of the plant. In badly affected fields, sometimes one-half of the crop is utterly destroyed. Careful search continued through several years has not availed to bring this species to my personal acquaintance.

For a full account of the parasitism of this species and its distribution in the United States see Jour. Myc., VII., p. 79; also Bull. 66, Agric. Sta. of Vermont.

Sub-Class EXOSPOREAE Rost.

1873. Exosporeae Rostafinski, Versuch, p. 2.

Spores developed, superficially, outside the fructification, which consists of sporophores, membranous, or slender and branching; spores white, stalked. A single genus,—

Ceratiomyxa Schroeter

1889. Ceratiomyxa Schroeter, Engl. u. Prantl, I., i., p. 16. For further synonymy, see under first species.

Sporangia none; spores superficial, borne on erect papillae or pillars, or even on the inside of minute depressions or pits; each spore surmounting a delicate pedicel or stalk. The spores on germinating give rise to amoeboid zoospores, which undergo repeated divisions, later become ciliate, and at length again amoeboid to blend into genuine plasmodia. At maturity the plasmodium gives rise to numerous minute divisions, each of which may lengthen in a direction perpendicular to the surface and bear a spore at the tip.

The homologies between the structures just described and the fructification of the ordinary slime-mould are somewhat obscure, if indeed any really exist. Are these minute reproductive bodies spores?—their behavior on germination is unique; are they sporangia?—the arrested development they exhibit is none the less puzzling. Perhaps the sporiferous pillars represent incipient stipes, the spores the uncombined fragments of what might otherwise have coalesced at the summit of the pillar to form a true sporangium.[16]

Several species have been recognized, all referable probably to one or two, or at most, four forms. That universally recognized alike in the literature of the past and in recent studies is,—

1. CERATIOMYXA FRUTICULOSA (Muell.) Macbr.

PLATE I., Figs. 7 and 7 a.

1729. Puccinia ramosa, bifurcata, etc. Micheli, p. 213, Tab. 92, Fig. 2. 1775. Byssus fruticulosa Mueller, in Fl. Dan., t. 718, Fig. 2. 1778. Tremella hydnoidea Jacquin, Misc., Vol. I., t. 16. 1783. Clavaria puccinia Batsch, Elench. Fung., p. 139, Fig. 19. 1791. Puccinia byssoides Gmelin, Syst. Naturae, p. 1462. 1791. Clavaria byssoides Bulliard, Champ. de la France, t. 415, Fig. 2. 1794. Isaria mucida Pers., Roemer, N. Mag. Bot., I., p. 121. 1801. Isaria mucida Pers., Syn. Meth., p. 688. 1805. Ceratium hydnoides Alb. & Schw., Consp. Fung., p. 258. 1811. Ceratiomyxa porioides (A. & S.) Schroet., Mycet., p. 26, var. 1829. Ceratium hydnoides Fries, Syst. Myc., III., p. 294. 1872. Ceratium hydnoides Wor. & Fam., Mem. Acad. Imp., Petersburg. 1887. Ceratium hydnoides DeBary, Comp. Morph. Fung., p. 432. 1889. Ceratiomyxa mucida Schroeter, Engl. u. Prantl Nat. Pflanz., I., i., p. 16. 1893. Ceratiomyxa mucida, Pers., Macbr., Bull. Nat. Hist. Iowa, II., p. 114. 1894. Ceratiomyxa mucida Schroet., Lister, Mycetozoa, p. 25.

Plasmodium in rotten wood, white or nearly transparent; when fruiting, forming on the substratum mould-like patches composed of the minute sporiferous pillars, generally in clusters of three or more together; spores white, ovoid, or ellipsoidal, smooth, 10-12x6 mu.

Very common, occurring in summer on shaded rotten logs, especially after warm showers and in sultry weather. Easily distinguishable from all similar moulds by the absence of mycelium or of anything like a hypha. In Europe the plant seems to be in autumn exceedingly common. Micheli not only described the form but figured it, nearly two hundred years ago. Micheli's figure is good, as is that of Mueller, Fl. Dan., l. c. Mueller referred the species to a Linnean genus Byssus, which seems to have included Algae rather than anything else, if one can determine its limits at all. The same thing is true of Tremella; but this name is now otherwise applied, as are all the other generic names down to Ceratium, Alb. & Schw. But this had been by Schrank preoccupied, 1793. See the reference above for 1889. As for specific name, there seems no reason to depart from the rule of priority, since Mueller's work is determinative.

Ceratiomyxa arbuscula, Berk. & Br., apparently a form of this, is cited from Toronto by Miss Currie. Massee gives it recognition; Lister as varietal. The sporophores are inclined to be simple, stipitate and dendroid.

C. filiforme of the English authors latest named is a wonderful thing and deserves a paragraph here, if not recognition as a distinct species. It occurs rarely; but once it appears, attracts attention. As in the historic species, the sporifers are white, stand more or less erect, but are every way finer and larger. Each individual sporifer rises like a stiff stem, as of white thread, 2-3 mm. high; at top a tuft of fruiting branchlets, more or less distinct. All taken together, we have a dense mat completely concealing the substratum and spreading out sometimes over an area of surprising extent, several centimetres square.

Common everywhere in summer on decaying sticks and wood of every description, especially in wet places. Alaska to Nicaragua, and probably around the world.

2. CERATIOMYXA PORIOIDES (Alb. & Schw.) Schroeter.

1805. Ceratium porioides Alb. & Schw., Consp. Fung., p. 359. 1829. Ceratium porioides Fries, Syst. Myc., III., p. 295. 1873. Ceratium porioides Fam. & Wor. Acad. Imp., XX., 3, p. 5. 1889. Ceratiomyxa porioides Schroet., Engl. u. Prantl, I., i., p. 16. 1894. Ceratiomyxa mucida Schroet. var. porioides Lister, Mycetozoa, p. 26. 1899. Ceratiomyxa porioides Alb. & Schw. (Schroet.), Macbr., N. A. S., p. 19. 1911. Ceratiomyxa porioides Alb. & Schw., Schroet., List. Mycet., p. 26, var.

Entire fructification confluent forming a mucilaginous mass, porose. Pores ample, angulate, at length radiate-dentate. Spores as in the preceding. Plasmodium yellow.

Of these two species Fries remarks: "... Duae sunt distinctissimae, inter has vero longa formarum intermediarum series." Famintzin and Woronin not only concur, but consider it were more fitting to place the present species in a distinct genus, as Polyporus is set off from Hydnum. A species based upon the color of the vegetative phase only, unconfirmed by any subsequent differential character in the fruit would seem somewhat hazardous. The color of the plasmodium is incident probably to varied nutrient environment. Pores, however, are usually in evidence.

Iowa, Tennessee, Missouri, etc.; probably common everywhere.

Sub-Class MYXOGASTRES (Fries) Macbr.

1829. Sub-order Myxogastres Fries, Syst. Myc., III., p. 67. 1833. Sub-order Myxomycetes Link, Handb. der Gew., 3, p. 405. 1833. Sub-order Myxomycetes Wallroth, Fl. Crypt., II., p. 333, in part. 1858. Class Mycetozoa DeBary, Bot. Zeitung, 1858, pp. 357-365, in part. 1889. Class Myxogastres Schroeter, Engl. u. Prantl, Nat. Pflanz., I., i., p. 16. 1892. Class Myxogastres (Fries) Massee, Monograph, p. 28. 1894. Class Mycetozoa Lister, Mycetozoa, p. 21, in part.

Except as just described, the slime-moulds present abundant, minute, unicellular spores, enclosed in sporangia more or less perfectly defined, and attended by peculiar thread-like structures, free or variously attached and conjoined, the so-called capillitium.

So far as known, the spores on germination give rise to zoospores, at first amoeboid, later ciliate, again amoeboid, conjugating in pairs, then, in some cases, at least, coalescing and dividing indefinitely to form the plasmodial or vegetative phase.[17]

Key to the Orders of the Myxogastres

Spore-mass black or violaceous, rarely ferruginous Series A

Spore-mass never black; usually some shade of brown or yellow, rarely purplish or rosy, etc. Series B

SERIES A

1. Capillitium present, delicate, thread-like; sporangia calcareous more or less throughout I. PHYSARALES

2. Capillitium present, thread-like, arising usually as anastomosing branches from a well-developed columella, which in a single genus contains lime; sporangia otherwise non-calcareous II. STEMONITALES

SERIES B

3. Capillitium none, or very imperfectly developed; spores of some shade of brown, rarely purplish III. CRIBRARIALES

4. Capillitium the inwardly produced irregular extremities of plates or tubules, which by their interweaving outwardly make up the aethalial wall; spores pale, ashen IV. LYCOGALALES

5. Capillitium made up of more or less distinctly sculptured threads, parietal or free, simple, branched, or reticulate; spores commonly yellow V. TRICHIALES

This sequence is meant to convey the idea that the presence of lime is indicative of differentiation less complete. That the plasmodium should at the outset eliminate, by refusing the unnecessary lime, is indicative of higher rank than that the lime should be carried until the last and then be crystallized out, or excreted by simple desiccation. The circumstance that the excreted lime may sometimes serve a protective purpose in the fruit, does not vitiate the general principle. In Series B the differentiation reaches a climax in the sculptured capillitium of the trichias.

ORDER I

PHYSARALES

Spores violaceous-black. The capillitium usually delicate and thread-like; peridium and capillitium, one or other or both, more or less extensively surcharged with lime. Peridium simple or double. Fructification various.

This order is recognizable by several characteristics, but is especially marked by the peculiar calcareous deposits which affect the capillitium or peridium, now one, now the other, more often both.

As here defined, the order Physarales includes two distinct families; of the one Physarum, of the other Didymium, is type.

Key to the Families of the Order Physarales

A. Fructification often calcareous throughout; capillitium intricate Physaraceae

B. Calcareous deposits, when present, affecting the peridium only, or sometimes the stipe, in the typical genus plainly crystalline; capillitium simple Didymiaceae

A. PHYSARACEAE

Key to the Genera of the Physaraceae

A. Fructification aethalioid 1. Fuligo

B. Fructification plasmodiocarpous or of distinct sporangia.

a. Peridium evidently calcareous.

i. Capillitium calcareous throughout 2. Badhamia

ii. Capillitium largely hyaline.

O Sporangia globose, etc.; dehiscence irregular 3. Physarum

OO Sporangia vasiform or more or less tubular

+ Dehiscence by a lid or more or less circumscissile 4. Craterium

+ Dehiscence irregular, peridium introverted 5. Physarella

b. Peridium apparently limeless, at least outside.

i. Plasmodiocarpous 6. Cienkowskia

ii. Sporangia distinct 7. Leocarpus

C. Extra-limital.

a. Sporangia stipitate, saucer-shaped, following No. 3. Trichamphora

b. Sporangia elongate allantoid, etc., following No. 1. Erionema

1. Fuligo (Haller) Pers.

1753. Mucor Linn., Sp. Pl. II., No. 1656 (?). 1768. Fuligo Haller, Hist. Helv., Nos. 1233-1235, in part. 1801. Fuligo Haller, Pers. Syn., p. 159. 1809. Aethalium Link, Diss., I, p. 42. 1829. Aethalium Fries, Sym. Myc., III., p. 92.

Sporangia undefined, obscurely woven in and out among each other forming usually a cushion-shaped aethalioid mass. The outer layer sterile, often calcareous, forming a fragile crust, more or less defined. The middle layer sporiferous with calcigerous capillitium. The lowest layer a membranous hypothallus.

The identity of this genus seems to have been recognized first by Haller, op. cit., but by Persoon more closely defined and illustrated. Link simply translated the name into Greek, for reasons less evident now, and in this was followed by Fries. Haller's designation is now probably securely fixed.

The sporigerous median structure of the fructifications, under whatever specific name or names, is entirely confused. Sporangial walls, if ever such there were, are hardly as such recoverable, seemingly indicated only, in the changes to which the aethalium submits as in the ripening the sporogenic plasm passes on to spores.

In the present state of our knowledge the forms of this genus present withal a most perplexing problem. Are they simply phases of a single species, or are they in style and in structure sufficiently constant in their admitted variety, to claim specific rank and separate description?

To follow the example of Greville and recognize in all the literature of two hundred years varied descriptions of a single type,—this were perhaps the easier and speedier disposal of the case. Fries thought so to treat the problem but was unable to keep faith with his own decision; for no sooner he states the genus monotypic than he proceeds forthwith to offer four varieties, a. b. c. d., viz. those by Persoon and others duly recognized as species.

Recent students all, however, seem to find convenience in specific division. All seem disposed to honor Dr. Peck's Fuligo ochracea whether or not by the name he gave; and of other varieties some seem impressed by the constancy of one, some of another characteristic, thus indicating that to careful observers all over the world there are differences that may be recognized, that have been recognized again and again. If there are two species there are certainly more. Out of the gatherings of many years one may set in order not less than five variations in the fruiting of Fuligo, five distinct types of fructification, to all appearing sufficiently constant for specific recognition.

It will be said, has been said, was said by Fries, that these variations are insignificant, "pendent ex aeris constitutione"; but as a matter of fact the several types now in question may be found on the same day, so that evidently something other than the atmospheric environment must determine.

Again it is said that the differences are in external form or color only, the spores in all cases almost if not quite the same. This is true; but specific characters are surface characters in fact: a species morphologically is merely the form in which a kind or genus presents itself. If the presentation be constant, for our convenience we say so, in bestowing a name. Whether in our present treatment the convenience is purely personal, students may decide.

However it all may be, there are in this part of the world many varying presentations of Fuligo capable of illustration and description; the same forms, perhaps, which have attracted the notice of the more acute mycologists in the older history of the subject. Some of these forms we here venture to describe, with such annotation as may show something of present knowledge.

Key to the Species of Fuligo

A. Aethalium 1 cm. or less; spores spherical 1. F. muscorum

B. Aethalium larger, or plasmodiocarpous, even sporangi-form, crust white, smooth, even, spores elliptical 2. F. cinerea

C. Aethalia larger, 2 cm. or more.

1. Cortex yellow, etc., not white; spores 6-8 mu 3. F. septica

2. Cortex nearly or quite wanting; spores 10-12 4. F. intermedia

3. Cortex white, a foamy crust; spores 15-25 5. F. megaspora

1. FULIGO MUSCORUM Alb. & Schw.

1894. Fuligo muscorum, Alb. & Schw. Lister, Mycetozoa, p. 67. 1875. Licea ochracea Peck, N. Y. Rep., XVIII., p. 55. 1879. Fuligo ochracea Peck, N. Y. Rep., XXXI., p. 56. 1894. Fuligo muscorum, Alb. & Schw., Lister, Mycetozoa, p. 67. 1911. Fuligo muscorum Alb. & Schw., Lister, Mycetozoa, 2nd ed., p. 87.

Plasmodium orange-yellow. Aethalium globoid, very small, 1 cm. or less, the cortex very thin, greenish yellow; sporangial walls not evident; capillitium well-developed, the numerous calcareous nodes fusiform or often branching, and connected by rather short, transparent internodes; spores coarsely warted, 10-11 mu.

This form seems to differ from F. septica chiefly in its constant diminutive habit of fruiting, in its delicate cortex, and in its spores, brighter, larger, and more coarsely warted. The descriptions and figure by Schweinitz seem referable to nothing else. First reported by Albertini and Schweinitz from Germany; by Schweinitz from the Carolinas; then by Dr. Peck described as a Licea from New York. It seems less commonly collected in the United States.

2. FULIGO CINEREA (Schw.) Morg.

PLATE X., Figs. 3, 3 a, and 3 b, and Plate XXIII.

1831. Enteridium cinereum Schw., N. A. F., No. 2365. 1875. Physarum ellipsosporum Rost., Mon. App., p. 10. 1884. Aethaliopsis stercoriformis Zopf., Pilzthiere, p. 150. 1894. Fuligo ellipsospora Lister, Mycetozoa, p. 67. 1896. Fuligo cinerea (Schw.) Morg., Cin. Soc. Nat. Hist., p. 105. 1899. Physarum ellipsosporum Rost., Macbr. N. A. S., p. 27. 1911. Fuligo cinerea Morg., List., Mycetozoa, 2nd ed., p. 88.

Plasmodium milk-white, watery. Plasmodiocarp long and widely effused, anon winding, here and there reticulate, always applanate; sometimes in form an aethalium, the peridial cortex membranous, firm, thick, and white. Capillitium well-developed, furnished with lime. Spores thin-walled, ellipsoidal, violaceous, plicate-rugose, 14-16 x 11-12 mu.

Not common. Found occasionally in shaded situations on piles of rotting straw or in the woods, especially on detritus of the bracken. The spores are many of them ellipsoidal; some are spherical; all are decidedly spinulose, perhaps might appear plicate-rugulose when dry or shrunken. Calcareous nodules very large and irregular, white.

Schweinitz, loc. cit., described this form as Enteridium cinereum. Rostafinski referred it to the genus Physarum, but was obliged to adopt also a new specific name, as that suggested by Schweinitz was already in use in the genus Physarum. Zopf, Die Pilzthiere, p. 149, founds a new genus on what seems to be the same form as here considered. This he publishes as Aethaliopsis stercoriformis Z. Massee regards the specimens discovered by Zopf as belonging to the genus Fuligo, and Lister regards Rostafinski's type as Fuligo, and includes Zopf's material under the Rostafinskian species.

This has been described as properly an American form; Lister cites other far localities.

3. FULIGO SEPTICA (Linn.) Gmel.

1753. Mucor septicus Linn., Sp. Pl. II., No. 1656 (?). 1763. Mucor ovatus Schaeff., Fung. Bav., p. 132, Fig. 192. 1791. Fuligo septica (Linn.) Gmel., Syst. Nat., p. 1466. 1826. Fuligo varians Sommf., Fl. Lapl. Sup., p. 231. 1809. Aethalium flavum Link, Diss., I., p. 42. 1829. Aethalium septicum Fr., Syst. Myc., III., p. 93. 1875. Fuligo varians Sommf., Rost., Mon., p. 134. 1892. Fuligo varians Sommf., Macbr., Bull. Lab. Nat. Hist. Ia. II., p. 160. 1894. Fuligo septica (Linn.) Lister, Mycetozoa, p. 66. 1899. Fuligo ovata (Schaeff.) Macbr., N. A. S., p. 23. 1911. Fuligo septica Gmel., Lister, Mycetozoa, 2nd ed., p. 86.

This remarkable and universal species presents as stated many forms and phases. Of these five have been selected as representative.

1. Form a. Plasmodium yellow; cortex yellow, or orange-brown, strongly calcareous friable; form indefinite F. ovata

2. Form b. Cortex less calcareous porose, yellowish brown, fructification definite, pulvinate F. rufa

3. Form c. Cortex smooth, persistent; fructification small, less than two inches F. laevis

4. Form d. Plasmodium yellow; cortex none; capillitium yellow, fructification thin, sometimes wide-spread F. flava

5. Form e. Plasmodium violaceous, dark; cortex almost none; whole mass reddish or violet F. violacea

1. Form a. Fuligo ovata (Schaeff.) Pers.

Plasmodium bright yellow; aethalium pale brown, or yellowish-ochraceous, of variable size and shape, one to many cm. in diameter, and one to two cm. thick, enclosed by a distinct calcareous crust, which varies in texture, thickness, and color; capillitium well developed but variable in color, form, and extent; spore-mass dull black, sooty; spores spherical, purplish brown, nearly smooth, 7-9 mu.

Under this name may be placed our most common form. Rising with an abundant yellowish creamy plasmodium from masses of decaying vegetation, lumber, sawdust, half buried logs, it creeps about with energy unsurpassed, coming to rest only in some position specially exposed, as the top of a log or stump, the face of a stone or post, or even the high clods of a cultivated field! The fructification is large, yellow, or at most pale ochraceous, the surface when mature extremely friable like dry foam. Bulliard figures this phase well on Plate 424, Fig. 2, and calls it Reticularia (Fuligo) hortensis, from its affecting the soils of gardens. More than thirty fructifications have appeared at one time, varying in size from one to twenty cm. in a field of potatoes, well tilled, and less than an acre in extent! Such is life's perennial exuberance on this time-worn old world of ours!

Schaeffer's plate CXII represents probably the same thing. So also Bolton's plate, CXXXIV. Sowerby's Fig. 2 on plate 199, and figures 1 and 2 on Greville's plate 272 possibly also depict this form. Persoon calls this F. vaporaria because it frequents hotbeds and the like, and believes this to represent the "untuosus flavus" of Linnee, although he thinks Schaeffer's specimens do not. The calcareous internal structure is white.

2. Form b, F. rufa Pers.

This type of Fuligo is very different from the preceding in form, habit, and color. In form it is much more definite, usually thick, well-rounded and with some solidity. The interior fructification is gray throughout, much less expanded than in a; in fact does not resemble a at all! The cortex is porose but firm, orange at first, but becoming tawny with age, even in the herbarium. Bulliard figures it well, plate 380, Fig. 1, and Sowerby's Fig. 1 on plate 399 is also good, as are also Greville's figure 3 on plate 272 showing the two colors referred to. Not uncommon in the forest from June till September, but far more rare than a: always well-marked, with no other forms associated.

3. Form c, F. laevis Pers.

This is a still more specialized type of the group. The fructification is usually small, smooth, about an inch in diameter and sometimes nearly as thick; the cortex rusty brown, enduring, persisting often when all the sporiferous grayish mass has been distributed through chinks, or from below. The figure 2 on plate X. shows this form. This also is a forest species, is autumnal rather, but may be taken sometimes as early as July. The cortex is not at all porose or spongy, in color reddish or brown, fragile indeed, but not to the touch, in the herbarium enduring for years.

4. Form d, F. flava Pers.

PLATE X, Figs. 2, 2 a, 2 b.

This is hardly F. flava of Persoon; rather of Morgan who uses Persoon's specific designation. Persoon cites Bolton's fig. CXXXIV, which is yellow indeed but is the ordinary presentation of F. septica. The form here considered is remarkable for its delicacy; extremely thin, perhaps one layer only of overlying elongate flexuous sporangia(?), covered by the merest shadow of a cortex in the form of yellow dust, soon lost: the capillitial structure yellow throughout; occurring upon fallen logs in moist dark woods; not common.

5. Form e, F. violacea Pers.

Plasmodium (Morgan teste) dark red, or wine-colored; the aethalium thin, two or three inches wide, covered by a cortex at first dull red and very soft, at length almost wholly vanishing, so that the entire mass takes on a purple-violet tint, upper surface varied with white; capillitium rather open, the more or less inflated, large, irregular nodes joined by long, slender, delicate, transparent filaments; spores dark violet, minutely roughened, spherical, about 7.5 mu.

Ohio, Tennessee. Probably everywhere, but not distinguished from 1.

Professor Morgan, who gave the genus under consideration much attention, regarded F. violacea as a form particularly well-defined. What the value of plasmodic color as a specific character in general, and how far such character is in the present case definitive, because constant, are points yet to be determined.

4. FULIGO INTERMEDIA Macbr. n. s.

Aethalium two to three cm. in greatest diameter, .5-1 cm. thick, covered with a thin, fragile, but not calcareous, greyish or brownish cortex; the spore-mass grey or violaceous-grey, firm, not at all sooty, the sporangia intricate, their walls more or less calcareous; capillitium not conspicuous; spores globose, pale purple, slightly roughened, 10-12 mu.

This form has been repeatedly sent me from Denver, Colorado, by Professor Bethel. I have refrained from publishing it, still anxious to believe that all fuligos on the face of the earth were of one species. In the species next following it must be admitted that the spore-variations are too wide to remain comfortably under shelter of a single specific name. The present species is not F. septica, neither is it F. megaspora; it is F. intermedia.

Colorado; Iowa.

5. FULIGO MEGASPORA Sturg.

1913. Fuligo megaspora Sturg., Col. Coll. Pub., p. 443.

Aethalium pulvinate one to three inches in diameter, covered with a thick spongy incrustation of lime, white or yellowish toward the base: sporangia convolute, the walls membranous, brittle, charged throughout with round white granules of lime, 1.5-2 mu in diameter: columella none: capillitium of delicate, colorless, anastomosing tubules, bearing toward the center large, white, branching calcareous nodules; spores spherical, or somewhat oval, dark purple-brown, rough-tuberculate, 15-20 mu.

This species differs as pointed out by Professor Sturgis, chiefly in the character of the spores, their unusual size and roughness.[18]

Colorado; Africa!—Robert Fries.

EXTRA-LIMITAL

Erionema Penzig

1898. Erionema Penzig, Die Myx. d. Fl. v. Beutenzorg, p. 36.

Sporangia plasmodiocarpous but distinct, cylindrical; capillitium intricate, elastic; nodules few.

1. ERIONEMA AUREUM Penzig

1898. Erionema aureum Penz. l. c.

Sporangia elongate, clustered, pendulous, yellow or grayish yellow, generally stipitate on long flaccid stalks, or sessile and interlacing: stipes yellow, blending with the hypothallus; capillitium intricate, expanding at maturity after the manner of Arcyria to several times the sporangial length, the nodules small, yellow; spores nearly smooth, violaceous-brown, 5-6 mu.

This unique form is near the fuligos which it resembles, especially when sessile, in its intricate sporangia. The spores also are those of the common Fuligo septica. The habit is however entirely different. Mr. Fetch describes clusters in Ceylon, hanging free, four to six cm. in length!

2. Badhamia (Berkeley) Rost.

1852. Badhamia Berkeley, Trans. Linn. Soc., XXI., p. 153. 1875. Badhamia Rostafinski, Monograph, p. 139.

Sporangia simple; peridial wall simple, thin, breaking irregularly; capillitium formed of abundant, richly anastomosing tubules, filled throughout their entire length with calcareous granules; the nodes often feebly represented; stipe poorly developed or wanting entirely; columella, except in forms sometimes assigned to the sub-genus Scyphium, poorly developed or none; spores frequently adherent in clusters.

The whole genus calls for careful and protracted study; and the present so-called species are like something new on the world; as full of vagaries as though but just entered upon their phylogenetic race.

This genus is closely related to Physarum, but differs in having the capillitium calcareous throughout. Forms occur and are included here, in which the capillitium, especially in some parts, is physarum-like, physaroid. Nevertheless, the distinctions hold good as a rule, and are at once diagnostic.

In capillitial differentiation the badhamias are definite and beautiful. The net in a typical species, as B. papaveracea, is throughout uniformly evenly tubular, the calcareous deposits delicate in the extreme, presenting, as the spores disappear, an elegant trabecular structure as if to support the persisting peridium if not the original content. In other forms the capillitium is physaroid, with swollen nodes, but heavily calcareous but not quite throughout. Badhamia, Physarum, Tilmadoche, Craterium present a consistent group, of which Physarum is the generalized expression.

Berkeley's idea of the genus was expressed as follows: "Peridium naked or furfuraceous. Spores in groups, enclosed, at first, in a hyaline sack." Rostafinski, while accepting Berkeley's generic name, redefined it, emphasized the calcareous capillitium, and made reference to the spore-adherence only to assert that Berkeley's description was, in this particular, based on mistaken observation. In some species, the spores do, in fact, show a tendency to cling together, a characteristic which Badham was perhaps first to notice; but that this is occasioned by their being surrounded by a sac or common pellicle has not been proved nor even suggested, by any subsequent investigator. Berkeley's genus was therefore founded upon a slight mistake; but we may conserve his rights in the premises if we write Badhamia (Berk.) Rost., and so keep history straight.

Key to the Species of Badhamia

A. Spores ovoid or ellipsoidal

a. Spores free 1. B. ovispora

b. Spores adherent 2. B. versicolor

B. Spores spherical

a. Sporangia yellow

i. Spores free 3. B. decipiens

ii. Spores adhering 4. B. nitens

b. Sporangia grey, spores free

i. Always sessile 5. B. panicea

ii. Stalked, at least some of them

O Stipe when present black