A. Dehiscence circumscissile or by the breaking up of the upper wall of the sporangium.a.Sporangia violet or purple1.C. paraguayenseb.Sporangia yellow2.C. aureumc.Sporangia white-capped.1. Sporangia obovoid or globoid3.C. leucocephalum2. Sporangia cylindric, elongate4.C. cylindricumB. Dehiscence by a distinct lid.a.Capillitium pale brown5.C. concinnumb.Capillitium white6.C. minutum
1.Craterium paraguayense(Speg.)List.
Sporangia gregarious, cylindrical or elongate cyathiform, stipitate, dark violet-red, the apex slightly roughened by pale calcareous granules, the peridium longitudinally wrinkled below; dehiscence, irregularly circumscissile; stipe darker, one-half the height of the sporangium, longitudinally wrinkled; capillitium dense, abundantly calcareous; spores violet-brown, minutely roughened, 7–8 µ.
In form resembling the following species, but instantly distinguished by the color, which is red throughout, tinged with purple or violet. The capillitium is badhamioid, as noted by Dr. Rex. Very distinct fromP. newtoniin color, form, habit, epispore, etc.
2.Craterium aureum(Schum.)Rost.
Sporangia gregarious, globose or obovoid, stipitate, yellow, erect, the peridial wall thin, especially at the summit, where at maturity it breaks up somewhat reticulately, leaving the persistent lower portion with an uneven margin above which projects the pale yellow capillitium; stipe short, orange, or brownish-red, arising from a small hypothallus; capillitium dense, yellow, the nodules not large, irregular, tending to form a pseudo-columella in the centre of the cup; spores minutely warted, violaceous-brown, 8–10 µ.
Fries regards this, which he namesC. mutabile, the most distinctly marked species of the genus; chiefly, as it appears, on account of the bright yellow color. This, however, varies. Some specimens before us are gray, showing only a trace of yellow below. In some European specimens a reddish tinge prevails. The form of the sporangium also varies. In typical specimens, unopened, the shape is almost pyriform; opened, we have a cylindric, oftenest lemon-yellow vase, mounted on a short striate stalk. But again, from the same plasmodium, we may have globose sporangia, opening so as to leave only a shallow, salver-shaped base. In this case the stipe is also longer. The plasmodium is said to be "clear lemon yellow."—Massee.
There seems little doubt that Schumacher had in mind the presentspecies in hisTrichia aurea. Rostafinski shows that Fries's synonym,C. mutabile, is founded on a mistake. The earlier specific name is therefore on Rostafinski's authority adopted.
Not common. Pennsylvania, New Jersey, North Carolina, Ohio, Iowa.
3.Craterium leucocephalum(Pers.)Ditmar.
Plate VIII., Fig. 5.
Sporangia gregarious, short-cylindric or ovate, pure white above, brown or reddish-brown below, stipitate, dehiscence irregularly circumscissile, the persistent portion of the peridium beaker-shaped; stipe short, stout, expanded above into the base of the peridium with which it is concolorous; hypothallus scant; capillitium white or sometimes, toward the centre, brownish, the calcareous nodules large, conspicuous, and persistent; spore-mass black, spores violaceous-brown, minutely spinulose, 8–9 µ.
Distinguished by its white cap from all except the next, from which the markedly different form serves as the diagnostic feature. In some gatherings, curious patches of yellow mark the otherwise snow white cap and sides; these are mere stains, or sometimes definite, crystalline, flake-like bodies, standing out in plain relief on the sporangial wall, or lurking in the larger nodules which are massed along the axis of the cup to form the pseudo-columella here strongly developed. Mr. Lister calls attention to these yellow flakes, and regards them as diagnostic. European specimens show the capillitium yellow, sometimes throughout!
The nomenclature question is here somewhat difficult. Fries heads his list of synonyms withPeziza convivalisBatsch. Batsch simply described Micheli's figure! Now there is nothing in Micheli's figure (Pl. 86, Fig. 14) to enable one to say with certainty which craterium Micheli had in mind, if craterium at all. Nor does Batsch help thematter when he offers the description following: "Stipitata; acute conica, patens; stipite subdistincto, lineari, brevi, valido.Albicans. In foliis hederae putridis." (Elenchus Fungorum, Batsch, 1783, p. 121.) There is nothing definitive here but the one word "albicans" quoted from Micheli. But this term is applicable the rather toC. minutum, the cups of which whiten with weathering. It may be, as insisted by Fries (Syst. Myc., III., p. 149), that Micheli drew crateriums; but if so, we cannot determine which species.
The specific name here adopted was applied by Persoon probably to this form; but Persoon likewise failed to distinguish the present species fromC. minutum(seeSyn. Fung., pp. 183, 184), and Fries,op. cit., p. 153. Ditmar,l. c., leaves no doubt as to what he figures and describes, and accordingly the name he first correctly uses is here adopted.
Not common. New England, Pennsylvania, Ohio, North Carolina, Iowa, Colorado, Washington, California; reported from Europe.
4.Craterium cylindricumMassee.
Plate XVI., Fig. 2.
Sporangia closely gregarious, very small, .5 µ or less, slender, cylindric, almost entirely white, stipitate, the peridium delicate, transparent although calcareous nearly to the base, opening by a dehiscence regularly circumscissile; stipe short, about one-third the total height, clear orange-brown, somewhat furrowed, rising from an indistinct hypothallus; capillitium very lax, physaroid, the calcareous nodules large, rounded, pure white, aggregated at the centre of the cup; spore-mass black, spores minutely roughened, violaceous-brown, 8–9 µ.
This is the common form in the United States. Massee describes it asC. cylindricumMass., and it seems not to occur in Europe.Lister has put it in withC. leucocephalum, from which its more delicate structure and elegant cylindrical shape certainly distinguish it. The dehiscence is even more regular than in the preceding species and approaches that ofC. minutumLeers., with bleached forms of which it must not be confused.N. A. F., 1400.
C. minimumBerk. & C. has here priority. Massee regards this name as indicating a distinct species. We have been unable to determine what the authors really had before them, and adopt accordingly the first available combination.
New England to Iowa and south; reported also from the orient.
5.Craterium concinnumRex.
Sporangia scattered, usually minute, broadly funnel-shaped, stipitate. The peridium simple, variously colored by innate lime granules, opening by a regular cap or operculum, brownish white, darkest in the centre, always more or less convex; stipe equalling the cup in height, dark brown, longitudinally ridged; the capillitium a close-meshed network, with small rounded or slightly angular masses of ochre-brown lime-granules, larger toward the centre; spores pale brown, minutely warted, 9–10 µ.
This species differs from the following, to which it seems most nearly allied, in form, color, as in the capillitium, and color of the spores. In habitat, however, it seems no less distinct, being found always (?) on the spines of decaying chestnut-burs lying on the ground, and in company with that other peculiar speciesLachnobolus globosus.
The range is probably that of the chestnut,Castanea dentataBorkhausen, east of the Mississippi River.
6.Craterium minutum(Leers)Fr.
Plate XV., Fig. 5.
Sporangia scattered, gregarious, cyathiform or turbinate, grayish brown, stipitate, the peridial wall rather thick, double, opening by a distinct lid which lies usually below the slightly thickened and everted margin of the cup; stipe paler, translucent, about equalling in height the peridial cup, longitudinally wrinkled, with hypothallus scant or none; capillitium physaroid, the calcareous nodules large, white, and generally aggregated at the centre of the cup; spore-mass black, spores by transmitted light violaceous, minutely warted, 8–10 µ.
This is the most highly differentiated of the whole series. The cup is shapely and well defined, while the lid is not only distinct, but is a thin, delicate membrane of slightly different structure when compared with the peridial wall. It is in all the specimens before us much depressed below the mouth of the sporangium, and the whole structure in our specimens corresponds with Fries' description ofC. pedunculatumTrent., while specimens received from Europe correspond to Fries' account ofC. minutumLeers. Nevertheless we are assured that the two forms are in Europe developed from the same plasmodium, and therefore adopt the earlier specific name as above.N. A. F., 2500. This is probablyFungoides convivalisof Batsch and Micheli.
In this species yellow sporangia are sometimes seen. Miss Currie reports from Toronto such variation and in Europe the case seems not unusual.
In fact, there is a yellow tinge about the sporangia of every species listed here, except the first. With the same exception, the plasmodium in every case is yellow.
Common throughout the eastern United States, west to Iowa, Colorado, and south to Louisiana; cosmopolitan.
5. PhysarellaPeck.
Sporangium pervious to the base, the interior walls forming a persistent spurious columella; capillitium composed of filaments withhere and there minute knot-like thickenings, straight tubes containing lime-granules extending from the exterior to the interior walls of the sporangium, persistently attached to the former.[31]
Such is Dr. Peck's original description of this most peculiar genus. The form of the sporangium in the only species is very variable, but in typical cases is vasiform, the peridial wall at the apex introverted. The capillitium is like that ofTilmadoche, except for the presence of the "straight tubes" emphasized in the original description. These are very remarkable and at once diagnostic. They take origin in the sporangial wall and pass across to the "columella"; but at the dehiscence of the sporangium, in typical cases, they remain attached at the points of origin, projecting as stout spine-like processes.
Physarella oblonga(Berk. & C.)Morg.
Plate VIII., Figs. 4, 4a, 4b, 4c;Plate XVI., Figs. 1, 1a, 1b, and 6.
Sporangia scattered or gregarious, typically cup-shaped or sub-infundibuliform, stipitate, erect or cernuous, but varying through low salver-shaped cups, to irregular applanate and sessile masses, the peridium thin but firm, tawny, roughened by numerous yellowish calcareous scales, at length ruptured above and often reflexed in the form of petal-like segments from which project upwards the spiniform trabecules of the capillitium; stipe when present long, terete, red, arising from a scant hypothallus and extended within the sporangium to meet the tubular "columella"; capillitium of delicate violaceous threads seldom branched or united, radiating from the columella with few calcareous nodular expansions, but supported by stout yellow calcareous trabecules, running parallel to the capillitial threads, long adherent to the sporangial wall; spores smooth, globose violet-brown, 7–8 µ.
Not uncommon in wet places. New York, Ohio, Iowa, South Dakota, Louisiana, Nicaragua; reported also from Ceylon, Java, etc.
Not the least remarkable feature of this remarkable species is the variation in the form of the fruit or sporangia. We have specimens from Louisiana (Rev. Langlois) which show no trace of columella, the whole structure involute and plicate, short stipitate, recalling the extremest complexity of such a species asP. polycephalum.Vid.Pl. XVI., Fig. 6. Moreover, in these specimens the calcareous deposits are white and not yellow, giving the entire fructification a grayish aspect. Yet there is no doubt we have here simply an exaggerated abnormality of the species; the spores are identical in size, color, and surface. Plasmodium bright yellow. Dr. Peck gave to his forms the namePhysarella mirabilis; but specimens sent by Michener of Pennsylvania, and by Berkeley and Curtis described asTrichamphora oblonga(Grev., II., p. 66), are the same thing.N. A. F., 1212.
Physarella lusitanicaTorrend is a globose form depressed above or betimes discoidal, occurring on Eucalyptus trees in Portugal.P. oblongais so variable in form that it sometimes suggests a different genus. Forms of it have been mistaken forFuligo gyrosaR., etc. Professor Torrend would include herePhysarum javanicum(Rac.), i. e.Tilmadoche javanicaas Raciborski saw it! We may not too often reflect that genera are purely artificial things set up for our convenience; but surelyPhysarellaas a natural genus is distinct enough to all.
6.CienkowskiaRost.
Fructification plasmodiocarpous, irregularly dehiscent, the wall a thin cartilaginous membrane destitute of lime, except the capillitial attachments within; capillitium scanty but rigid, and characterized everywhere by peculiar hook-like branchlets, free and sharp-pointed, the spores as inPhysarum, etc.
The genus contains, so far, but a single species:—
Cienkowskia reticulata(Alb. & Schw.)Rost.
Plate XIV., Figs. 2, 2a, 2b.
Plasmodiocarp an elongated, irregularly limited, close-meshed net, closely applied to the substratum, the wall thin, transversely rugulose, and roughened, dull orange-yellow, splashed here and there with scarlet, anon entirely red, within marked by transverse calcareous ridges, supporting in part the calcareous system of the capillitium; capillitium of delicate, rigid, reticulating yellow tubules or threads with numerous free, uncinate or sickle-shaped branchlets, and large, irregular, calcareous plates, more or less transverse to the axis of the sporangium, attached to the peridial walls, as if to form septa, ordinary calcareous nodules few; spore-mass jet-black, spores, by transmitted light, violaceous, minutely roughened, 9–10 µ.
A very rare species, as it appears, easily recognized by the Coddington even, much more by the microscopic characters quoted; probably often overlooked by the collector, as to the naked eye it presents the appearance of some imperfectly developed, dried-up plasmodium. Very unlikePhysarum serpulaMorgan, not infrequently offered by collectors asCienkowskia. It isDiderma reticulatumof Fries, who, strangely enough, thought it might be a plasmodial phase ofDiderma(i. e.Leocarpus)fragile(Syst. Myc., III., p. 102).
Eastern United States, Europe, Java, Ceylon, California. See underL. fragilis, next following.
7. Leocarpus(Link)Rost.
Sporangia sessile, or short stipitate; peridial wall double, the outer thick, destitute of lime, polished, shining within and without, the inner very delicate, enclosing the capillitium and spores; capillitium of two, more or less, distinct systems, the one a delicate network of hyaline, limeless threads, the other calcareous throughout, or nearly so, the meshes large and the threads or tubules broad; columella none, although a pseudo-columella may sometimes be detected.
This genus was by Link established on characters purely external. Rostafinski supplemented Link's definition by calling attention to the peculiar character of the capillitium and to microscopic characters in general. The outer peridium is thick and strong, unlike the ordinary structure inPhysarum. Some physarums, however, have a very similar outer wall;P. brunneolum, for instance; compare the peridium ofP. citrinellum. In dehiscence and structure there is also some resemblance to some species ofDiderma, and by Persoon and Fries the common species was so referred, but the capillitium is again definitive.
A critical study of all these things really begins with Rostafinski's microscope. Under his definition of the present genusP. squamulosumWingate andP. albescensEll. might well be entered here. Such course at present would but increase confusion, and until by future research the ontogeny of all these, and so their relationship, shall be more exactly known, the genus may be left with its historic species,—montotypic.
Leocarpus fragilis(Dickson)Rost.
Plate VIII., Figs. 3, 3a, 3b.
Sporangia gregarious or clustered, sessile or stipitate, obovoid, rusty or spadiceous-yellow, shining; peridium opening at maturity in somewhat stellate fashion; stipe filiform, white or yellow, weak and short; spores dull black, spinulose, 12–14 µ.
A common species, distributed through all the world, Iowa to Tasmania. Recognizable at sight by the form and color of the sporangia. In shape and posture these resemble the eggs of certain insects, and, occurring upon dead leaves, generally where these have drifted against a rotten log, they might perchance be mistaken for such structures. With no other slime-moulds are they likely to be confused. The outer peridium opens irregularly, or more rarelystellately. At centre of the capillitium is a calcareous core. The plasmodium is yellowish white, spread in rich and beautiful reticulations.N. A. F., 1123.
A plasmodiform gathering of this species which will be mistaken for an entirely different thing, is yellow, sessile, and hasadherentspores; looks like a badhamia, but is after all a leocarpus and probably belongs here. The spores are irregularly clustered and the badhamioid section of the capillitium seems now dominant.
California.
B. DIDYMIACEÆ
Key to the Genera of the Didymiaceæ
1. Fructification æthalioid1.Mucilago2. Fructification plasmodiocarpous, or forming more often distinct sporangia.a.Calcareous deposits crystalline, stellate2.Didymiumb.Calcareous deposits amorphous, peridium double3.Didermac.Calcareous deposits in form of scattered scales4.Lepidodermad.Peridium double, the outer gelatinous5.Colloderma
1. Mucilago(Mich.)Adans.
Fructification æthalioid, consisting generally of large cushion-shaped masses covered without by a white foam-like crust; within, composed of numerous tubular sporangia, developed from a common hypothallus, irregularly branched, contorted and more or less confluent; the peridial wall thin, delicate, frosted with stellate lime-crystals, which mark in section the boundaries of the several sporangia; capillitium of delicate threads, generally only slightly branched, terminating in the sporangial wall, marked with occasional swellings or thickenings.
By the descriptions offered by most authors, and especially by Rostafinski's figures (Mon., Pl. ix.), a pronounced columella is called for in the structure ofSpumaria. The individual sporangia rise from a common hypothallus, and occasionally portions of this run up andgive to a sporangium the appearance of being stipitate. Sometimes also this upper extension of the hypothalline protoplasm passes beyond or behind the base of the sporangium or between two or more, and is more or less embraced by these in their confluent flexures. This, it seems, suggested Rostafinski's elaborate diagram, Fig. 158; at least, none other form of columella is shown by American materials at hand.
1.Mucilago spongiosa(Leyss.)Morgan.
Plate VII., Fig. 6, 6a, 6b.
Æthalium white or cream-colored, of variable size and shape, half-an-inch to three inches in length and half as thick, the component sporangia resting upon a common hypothallus and protected by a more or less deciduous calcareous porous cortex; peridial walls thin, and where exposed iridescent, generally whitened by a thin coating of lime crystals; capillitium scanty, of simple, mostly dark-colored, slightly anastomosing threads; columella indefinite or none; hypothallus white, spongy; spore-mass black, spores violaceous, exceedingly rough, large, 12–15 µ.
Very common in all the eastern United States and the Mississippi valley, south to Texas. The plasmodium is dull white, of the consistence of cream, and is often met with in quantity on beds of decaying leaves in the woods. In fruiting the plasmodium ascends preferably living stems of small bushes, herbaceous plants, or grasses, and forms the æthalium around the stem some distance above the ground. The cortex varies in amount, is also deciduous, so that weathered or imperfectly developed forms probably represent the var.S. cornutaSchum.
Two varieties of this species are recognized; the one from Bolivia, var.dictyosporadescribed by Mr. R. E. Fries (Arkiv. for BotanikBd. 1, p. 66) differs from the type chiefly in its finer capillitial threads its darker spores with longer spines and fine reticulate sculpture; the other from Colorado, var.solidadescribed by ProfessorSturgis differs, as the name implies, principally in its greater compactness and slightly smaller calcareous crystals; a desert phase.
2. Didymium(Schrad.)Fr.
Sporangia distinct, stipitate, sessile or even plasmodiocarpous, never æthalioid; the peridium thin, irregular in dehiscence, covered with a more or less dense coating of calcareous crystals; columella more frequently present; capillitium of delicate threads, simple or sparingly branched, extending from the columella to the peridial wall.
The genusDidymium, as set up by Schraderl. c., included a number of species now assigned toDiderma,LepidodermaorLamproderma. Fries set out the didermas; DeBary and Rostafinski completed the revision by setting out the remaining alien forms.
The genus is among Myxomycetes instantly recognized by the peculiar form of its calcareous deposits, stellate crystals coating, or merely frosting, usually distinct sporangia.
Key to the Species of Didymium
1. Lime-crystals merely whitening the peridial wall.A. Fructification plasmodiocarpous.a.White.O Capillitium with adherent vesicles1.D. complanatumOO Capillitium simple2.D. anellusOOO Capillitium much combined; spores 10–13 µ3.D. wilczekiiOOOO Capillitium crystal-bearing18a.D. anomalumb.Yellow or tawny4.D. fulvumB. Fructification normally of distinct sporangia.a.Sporangia sessile or nearly so; outer calcareous wall conspicuously developed5.D. crustaceumb.Sporangia plainly stipitate.i. Peridium much depressed; umbilicate below.O Stipe white6.D. squamulosumOO Stipe black.+ Larger, about 7.5–1 mm.7.D. melanospermum++ Small, about .5 mm.8.D. minus+++ Sporangia discoid9.D. clavusii. Peridium small, globose.O Stipe dark brown or black; columella dark, obsolete or none.10.D. nigripesOO Stipe generally paler, of various tints of brown, orange, etc.+Columella pale or white, nearly smooth11.D. xanthopus++ Columella, yellow, discoid, rough12.D. eximiumiii. Peridium turbinate, columella hemispheric13.D. trochusiv. Peridium annulate14.D. annulatum2. Calcareous crystals forming a distinct crust.A. Fructification wholly plasmodiocarpous15.D. dubiumB. Sporangia ill-defined, sessile, plasmodiocarpous.a.Spores generally nearly smooth16.D. difformeb.Spores very rough, obscurely banded17.D. quitenseEXTRA-LIMITALa.Sporangia discoid, spores reticulate18.D. intermediumb.Stipe, columella, peridium, orange-brown19.D. leoninum
1.Didymium complanatum(Batsch)Rost.
Plate XVI., Fig. 8.
Fructification plasmodiocarpous, creeping, flattened, vein-like, annulate or reticulate, the dark-colored peridium covered with white, but not numerous crystals; hypothallus none; columella none; capillitium much branched, violaceous threads combined to form a rather dense net which bears numerous, peculiar, rounded vesicles, yellowish in color, 30–50 µ in diameter; spores minutely warted, 7–9 µ, violaceous-brown.
The defining characteristics here are the curious supplementary vesicles. These are evidently plasmodic, embraced, shot-through, by all the neighboring capillitial threads, withal warted like a spore. They remind of the curious, belated, spore-like but giant cells found in stipes, as in arcyriaceous forms. With all the wealth of his prolix,poetic, metaphoric tongue, the Polish author gives them abundant consideration. In theMon., Tab. IX., Figs. 166 and 180, he clearly shows the structure, although in the explanation of the plate he has strangely mixed this species withD. crustaceumFr. UnderD. serpulaFries may refer to the present species, although there is nothing in his description to determine the fact. The same thing may be said of the description and figures of Batsch. Rostafinski, in theMonograph, seems to have been satisfied as to the identity of Batsch's materials: in theAppendix, he writesD. serpula, but gives no reason.
Rare. New York. England, France, Germany.
2.Didymium anellusMorgan.
Plate XVIII., Fig. 7.
Plasmodiocarp in small rings or links, then confluent and elongated, irregularly connected together, bent and flexuous, resting on a thin venulose hypothallus, or sometimes globose, the peridium dark colored, with a thin layer of stellate crystals, irregularly ruptured; capillitium of slender, dark-colored threads, which extend from base to wall, more or less branched, and combined into a loose net; columella a thin layer of brown scales; spores globose, very minutely warted, violaceous, 8–9 µ.
This minute species resembles a poorly developed, or sessile, phase ofD. melanospermum. Some of the sporangia (?) are spherical; such show a very short dark stalk. The columella is scant, and the spores are smaller than those ofD. melanospermum.
Ohio. Reported more recently from Europe and Ceylon.
3.Didymium wilczekiiMeylan.
Plasmodiocarpous, dehiscing irregularly, columella scant; capillitium abundant, the threads brown, anastomosing, forming an elastic net; spores purple-brown, minutely spinulose, 10–12 µ.
Resembling plasmodiocarpous forms ofD. squamulosum, a montane var.; small and delicate, our specimen about 16 × 6 mm. Evidently not common; collected but once by Professor Bethel at an altitude of 11,000 feet, Rocky Mountains of Colorado.
Reported in Switzerland and Sweden.
In certain Swiss gatherings made in 1913 Miss Lister finds capillitial threads withspiraltæniæ as inTrichia! (Jour. of Bot., Apr. 1914.) The threads in our specimen are roughened, somewhat as inD. squamulosum, though less strongly; the spores are nearly smooth, fuliginous at first, paler and violaceous when saturate.
4.Didymium fulvumSturgis.
Sporangia gregarious, sessile, elongate or forming curved plasmodiocarps, sometimes confluent, rarely sub-globose, concave beneath, pale-raw-umber in color, 0.5–0.8 mm. in diameter, occasionally seated on a concolorous, membranous, lime-encrusted hypothallus which may form pseudo-stalks; sporangium wall membranous, stained with yellow blotches, thickly sprinkled with clusters of large acicular crystals of pale-yellowish lime; columella very much flattened or obsolete; capillitium an abundant network of delicate, almost straight or flexuose, pale-purple or nearly hyaline threads, frequently with dark, calyciform thickenings as inMucilago, and occasionally showing fusiform, crystalline blisters; spores dark-purplish-brown, coarsely tuberculate, the tubercles usually arranged in curved lines, paler and smoother on one side, 12.5 to 14.5 µ. Colorado.
5.Didymium crustaceumFr.
Sporangia closely aggregated, globose, or by compression deformed, sessile, snow-white, by virtue of the remarkably developed covering of calcareous crystals by which each sporangium is surrounded as if to form a crust, the peridium membranous, colorless, usually shrunken above and depressed; columella pale, small, or obsolete; hypothallus scant or vanishing; capillitium of rather stout violaceous threads seldom branched except at the tips, where they are pale and oftenbifid, or more than once dichotomously divided; spores strongly warted, globose, violet-brown, 10–13 µ.
This species has in some ways all the outward seeming of a diderma, but cannot be referred to that genus because of the crystalline character of its crust. This is a very marked structure; loosely built up of very large crystals, it is necessarily extremely frail, nevertheless persists, arching over at a considerable distance above the peridium proper. Sometimes, however, caducous, evanescent.
The sporangia are said to be sometimes stipitate. This feature does not appear in any of the material before us. Lister inMycetozoaPl. XL.,c.draws the capillitium much more delicate than it appears in our specimens. The hypothallus is sometimes noticeable under some of the sporangia where closely crowded, but is not a constant feature.
Rostafinski (by typographical error?) confused in theMonograph, pp. 164, 165, this species with Persoon'sPhysarum confluens. In theAppendixhe substitutes the Friesian nomenclature. Persoon's description of his species is insufficient, and throws no light on the problem whatever.
Rare. Iowa; Black Hills, South Dakota. Reported common in Europe. Canada; Vancouver Island to the St. Lawrence.
6.Didymium squamulosum(Alb. & Schw.)Fries.
Sporangia, in typical forms, gregarious, globose or depressed-globose, gray or snow-white, stipitate; the peridium a thin iridescent membrane covered more or less richly with minute crystals of lime; the stipe when present, snow-white, fluted or channelled, stout, even; columella white, conspicuous; hypothallus usually small or obsolete; capillitium of delicate branching threads, usually colorless or pallid, sometimes with conspicuous calyciform thickenings; spores violaceous, minutely warted or spinulose, 8–10 µ.
This, one of the most beautiful species in the whole series, is remarkable for the variations which it presents in the fruiting phase. These range all the way from the simplest and plainest kind of a plasmodiocarp with only the most delicate frosting of calcareous crystals up through more or less confluent sessile sporangia to well-defined elegantly stipitate, globose fruits, where the lime is sometimes so abundant as to form deciduous flaky scales. The hypothallus, sometimes entirely wanting, is anon well developed, even continuous, venulose, from stipe to stipe. The capillitium varies much in abundance as in color; when scanty, it is colorless and in every way more delicate, when abundant, darker in color and sometimes with stronger thickenings.
D. fuckelianum Rost., as shown inN. A. F., 2090, and in some private collections, seems to be a rather stout phase of the present species; the stipe is more abundantly and deeply plicate, is sometimes tinged with brown, and the capillitium is darker colored and coarser than in what is here regarded as the type of the species; but withal the specimens certainly fail to meet the requirements of Rostafinski's elaborate description and figure,Mon., p. 161 and Fig. 154.
D. effusumLink, probably stands for a sessile form of this species, but Link's brief description (1816) is antedated by the much better one of Albertini and Schweinitz,l. c.
Generally distributed throughout the wooded regions of North America, from New England to Nicaragua, and from Canada to California. Not uncommon about stable-manure heaps, in flower beds, and on richly manured lands. July, August.
Nicaragua specimens not only show a continuous vein-like hypothallus, but have the peridia often confluent, the columellæ in such cases confluent, the stipes distinct. Furthermore, the largest spores reach the limit of 12.5 µ, and perhaps the larger number range from 10–12.5 µ, and all are very rough. This corresponds withD. macrospermumRost., which is distinguished, says the author (Mon., p. 162,opis), "chiefly by the large and strongly spinulose spores." However, the same sporangium in our Central American specimens yield spores 9.5–12.5 µ, a remarkable range. So thatD. macrospermumon this side the ocean, at least, cannot be distinguished fromD. squamulosum, as far as spores are concerned. A similar remark may be made relative to the form of the columella which Rostafinski, in his figures especially, would make diagnostic. The columella in the sporangia with largest and roughest spores is that of a perfectly normalD. squamulosum.
7.Didymium melanospermum(Pers.)Macbr.
Plate VII., Figs. 3, 3a.
Sporangia gregarious, hemispheric, depressed, umbilicate below, stipitate or sessile; the peridium firm, dull brown in color, frosted with minute crystals of lime, breaking irregularly; stipe, when present, short, stout, dull black, opaque, arising from a broad base or hypothallus; columella large, prominent; dark-colored, rough above, concave below; capillitium of more or less sinuous, usually dark-colored threads, sparingly branched, and often with calyciform thickenings; spore-mass black, spores by transmitted light pale, purplish-gray, spinulose or rough, 10–12 µ.
A well-marked and common species, distinguished by its depressed sporangium and dark-colored, opaque stipe. The latter is usually very short, almost completely concealed in the concavity of the umbilicate sporangium. The columella is dark-colored, forming the floor of the peridial cavity.
Persoon first named this species as here. Later on,Uster's Ann., XV., 6, he substitutedvillosumas a more appropriate specific name. Schrader rejects both names given by Persoon as unsuitable, and suggestsfarinaceum. Schrad.,op. cit., p. 27.
New England, Ohio, Missouri, Alabama, Iowa, Nebraska; Europe; probably cosmopolitan.
8.Didymium minusLister.
Plate X., Figs. 4, 4a, 4b.
Sporangia gregarious, depressed-globose, umbilicate below, whitish or gray, small, about ½ mm., stipitate; stipe erect, rather slender, black, faintly striate, about equal to the sporangium in the horizontal diameter; columella distinct, dark brown, globose or depressed-globose, attaining in some cases the centre, rough; capillitium delicate, almost colorless, radiating, sparsely branched; spores in mass dark brown, by transmitted light violet-tinted, minutely roughened, 8–10 µ.
Probably more common than the preceding, and generally mistaken for it. Distinguished by its smaller size, longer and more slender stem, and general trim, well-differentiated appearance. Certainly very near the preceding, of which Mr. Lister regards it as merely a variety. Professor Morgan thought it in this country the more common form.
New York, Ohio, Iowa; reported from Europe, Africa, South America.
9.Didymium clavus(Alb. & Schw.)Rabenhorst.
Sporangia gregarious, pale gray, discoid or pileate, depressed, stipitate; the peridium dark-colored, frosted with calcareous crystals above, naked below; stipe short, slender, tapering upward, furrowed, arising from a hypothallus more or less distinct, black; columella obsolete; capillitium of delicate threads, pale or colorless, little branched; spores violaceous, pale, nearly smooth, 6–8 µ.
This species is well differentiated, easy of recognition by reason of its peculiar discoid sporangium, calcareous above, naked and black beneath.D. neglectumMassee, reported from Philadelphia, is said to be a slender form of the present species. The figures ofD. clavusby Albertini and Schweinitz are excellent, as also the description.
Not common. Pennsylvania, Ohio, Iowa.
10.Didymium nigripes(Link)Fries.
Plate VII., Figs. 2, 2a, 2b.
Sporangia gregarious, globose or hemispheric, umbilicate beneath, small, white, stipitate; the peridium smoky, covered with minute calcareous crystals; stipe slender, erect, black, opaque; hypothallus scutate, black; columella distinct, globose, black or dark brown; capillitium of delicate threads, pale brown or colorless, with occasional brown thickenings or nodes, sparingly branched; spores pale, violaceous by transmitted light, minutely warted, 6–8 µ.
This isD. microcarponRost. Fries,l. c., acknowledges the priority of Link's appellation, and discardsmicrocarpon. Rostafinski adoptedmicrocarponsimply because he thought it more appropriate. Fries describes the columella "none or black." It is doubtful whether we have the typical Friesian form on this continent. The fructification is in our specimens small, about .4 mm., and the spores, as noted by Morgan, small; otherwise the species is hardly more than a variety of the next. Under the nameD. nigripesLister groups our Nos. 10, 11, 12.N. A. F., 1393, represents Dr. Rex's conception of the present species.
Not common. New York, Ohio, Iowa.
11.Didymium xanthopus(Ditmar)Fr.
Plate XVI., Fig. 10.
Sporangia gregarious, white, globose, slightly umbilicate, stipitate; the peridium thin, and nearly or quite colorless, frosted with crystals of lime; the stipe yellowish or yellowish brown, corneous, erect, subulate,slender; hypothallus none; columella pale or white, turbinate, globose or depressed-globose; capillitium of dull brown, or colorless threads more or less branched, always white at the tips; spores violaceous, nearly smooth, 7.5–8.5 µ.
This seems to be the most common form in the United States. It is distinguished from the preceding by the longer, more delicate, generally orange-yellow, stem with pale or white columella. The spores also average a shade larger.N. A. F., 412 and 2089, are illustrations ofD. xanthopus. The columella in blown-out specimens is very striking, well confirming the diagnosis of Fries, "valde prominens, globosa, stipitata, alba." Berkeley makes the color of the capillitium diagnostic ofD. proximum, but this feature is insufficient.
Eastern United States; common.
12.Didymium eximiumPeck.
Plate XVI., Figs. 11, 11a, 11b.
Sporangia scattered, dull grayish-yellow or gray, depressed-globose, umbilicate, minute, stipitate; the peridium comparatively thick, tenacious, especially persistent below, tawny or yellow; the stipe pale brown or orange, erect, even or slightly enlarged at base; hypothallus scant or none; columella prominent, more or less discoidal, rough, or spinulose, especially on the upper surface, yellow; capillitium not abundant, pale fuliginous, often branching and anastomosing so as to form a loose net; spores nearly smooth, dark violaceous by transmitted light, 8.5–9.5 µ.
The species differs fromD. xanthopusin several particulars,—in the much firmer, more persistent, and less calcareous peridium, in the more complex capillitium, in the darker and larger spores, and especially in the peculiar and prominent columella, which is not only rough, but even "sometimes spinulose even to the extent of long spicules penetrating to one-third the height of the sporangia."N. A. F., 2493.
As stated under No. 8, these last two species are called varieties only ofD. nigripes. They are so retained inMycetozoa, 2nd ed.Since, however, they are the usual presentation of the species in the United States, it seems wise to let them stand for the present, as here. They are quite distinguishable;D. eximiumespecially well marked.
Apparently rare, it yet ranges from New York to eastern Iowa, in colonies rather large. Okoboji Lake;—fine!
13.Didymium trochusList.
Sporangia plasmodiocarpous, hemispherical or turbinate, white, sessile or very short-stalked, cream-colored or white; peridium double, the outer shell-like, the inner membranaceous, more or less adherent to the outer, both caducous together, leaving the thickened base surrounding an expanded columella; stipe, when present, very short, stout; capillitium colorless, nearly simple; spores brownish-purple, strongly warted, 9–10 µ.
On decaying leaves, rotten cactus, yucca, etc., Monrovia, California;Bethel.
Reported from England on beds of leaves or straw; in Portugal Dr. Torrend finds it on orindead leaves ofAgave americana! Evidently an American species, and belonging to arid regions; its occurrence in England surprising!
14.Didymium annulatumMacbr. n. s.
Plate XX., Figs. 4, 4a.
Sporangia small, scattered, annulate, not only without columella but perforate when the stipe is broken, umbilicate above and below, grey, coated with crystalline frustules, opening irregularly about the periphery; stipe white, or pallid, fluted, tapering upward from a distinct hypothallus; capillitium scanty consisting of delicate, sparsely branching threads, the branchlets anastomosing more or less at length, attached to the peridial wall, radiating from the rim of the slightly depressed top of stipe, without special thickenings save at the insertion of the ramules a triangular enlargement is usual and of dark or pallid shade; spores smooth; however they show three or four spotson the hemisphere and other minute but variable markings; 9–10 µ. Seattle, Washington.
Differs fromD. nigripesin color of the stipes, capillitium, spore-diameter, etc.
15.Didymium dubiumRost.
Fructification wholly plasmodiocarpous, snow-white, small, 2–6 mm., flat and thin; the outer wall double, membranous within, calcareous-crystalline without; columella none; capillitium simple of rather thick, vertical, brown threads, sparingly united laterally, and only occasionally furcate at the ends, especially above; spores minutely spinulescent, violaceous pale, 12–15 µ.
Massee thought English specimens out of harmony with the original description and gave them a new name. To refuse this, Lister enlarges the range of spore-measurements and disregards some of Rostafinski's specifications as to capillitium. Our specimens are as described.
Bohemia. England. Shores of Lake Okoboji, Iowa.
This is indeed a doubtful form. It differs fromD. difformechiefly in that the outer calcareous shell is not smooth, but is covered with abundant loose crystals, frosted. The spores are paler but about the same size. The frosting may be incident to local climatic conditions at the time and place of desiccation.
16.Didymium difformeDuby.
Plasmodiocarpous, the smooth, white outer peridium separable from the thin, colorless or purplish inner layer; capillitium of rathercoarse, flat, dichotomously branching threads, broader below; spores minutely warted, or almost smooth, dark brown, 12–14 µ.
The white crust-like outer wall has more than once carried this species intoDiderma. It is still doubtful whether we are here dealing withChondrioderma calcareumRost. Miss Lister cites a variety,S. difforme comatum, with more abundant capillitium which may represent Rostafinski's species.
Evidently rare in the United States; reported more common in Europe and eastward. In our specimens the crust-like outer peridium shows crystals on the broken edge only; the body of the object, as its outer surface seems to be amorphous.
17.Didymium quitense(Pat.)Torr.
Sporangia more or less plasmodiocarpous, scattered, depressed, white; the outer peridium distinct, crust-like, remote from the thin membranous inner wall; columella undefined; capillitium brown, much branched, forming a network especially outwardly; spores very dark violaceous-brown, rough with a tendency to obscure reticulation; 12–14 µ.
This species is different fromD. difformechiefly in the rougher and somewhat banded epispore. It is reported from Ecuador by Father Torrend, and from Colorado mountains by Dr. Sturgis to whose kindness I am indebted for the specimens here described. Evidently a high mountain species.
Colorado.
18a.Didymium anomalumSturg.
Plate XIX., Figs. 13 and 13a.
Sporangia in the form of very thin effused grey plasmodiocarps, 2–10 cm. long, 1 mm. or less in thickness. Wall single or membranous, hyaline or yellowish, with rather scanty deposits of small, stellatelycrystalline or amorphous lime. Columella none. Capillitium consisting entirely of straight membranous, tubular, columns, extending from the base to the upper wall of the plasmodiocarp, 7–22 µ thick and usually containing small crystalline masses of lime. Spores bright violet-brown, minutely and irregularly spinulose, 10–11.5 µ diam.
Hab. on the inner bark of Populus. Colorado Springs, Colo., July 1911.
Our specimens by the courtesy of Dr. Sturgis.
EXTRA-LIMITAL
18.Didymium intermediumSchroeter.
Sporangia clustered or gregarious, discoidal and umbilicate below, or lobed or convolute, greyish white, stipitate; stipe pale yellow, tapering upwards, stuffed with lime crystals, expanding into the yellowish, discoidal, recurving columella; capillitium colorless, more or less branching; spores dark purple-brown, irregularly reticulate, 9–12 µ.
Differs fromD. squamulosumin the reticulate epispore. Brazil.
19.Didymium leoninumBerk. & Br.
Sporangia gregarious, sub-globose, covered more or less completely with white or yellowish deposits of crystalline lime, stipitate; stipes short, orange or brown, containing lime, enlarged to form the globose orange columella and often connected at base by a venulose hypothallus; capillitium of slender threads, anastomosing, colorless at the tips; spores violet-grey, minutely warted, 7–9 µ.
LikeLepidoderma tigrinum, but has different calcic crystals.
Java and Ceylon.
3. DidermaPersoon
Sporangia plasmodiocarpous or distinct, sessile or stipitate; the peridium as a rule double, the outer wall generally calcareous with the lime granules globular, non-crystalline, the inner wall very delicate and often, in the mature fructification, remote from the outer; columella generally prominent.
The genusDidermais usually easy of recognition, by reason of its double wall, the outer, crustaceous, usually calcareous, and its limits remain substantially as originally set by Persoon. His definition is as follows:—
"Peridium ut plurimum duplex; exterius fragile; interius pellucens, subdistans. Columella magna, subrotunda. Fila parca latentia."—Syn. Meth. Fung., p. 168.
Rostafinski changed the name of the genus toChondrioderma(chondri, cartilage), seemingly at De Bary's suggestion, and seems to have regarded Persoon's definition as applicable to those species only in which the wall is not only plainly double, but in which the two walls are as plainly remote from each other. More especially he esteemed a new generic name necessary, since he regarded several included species, asD. spumarioides,D. michelii, etc., monodermic.
Since it is doubtful whether any diderma is really monodermic, and since Persoon's definition in any case seems sufficiently elastic, we have seen no reason to discard the older name. Persoon'sDidermawhen established,l. c., includedD. floriforme. He made some confusion in his later work by admitting some physarums. This induced Schrader to throw all the didermas into his new genus,Didymium.
According to the nature of the sporangial wall, the species fall rather naturally into two sections:—