1870. _Physarum citrinellum_ Peck, _Rep. N. Y. Mus._, x.x.xI., p. 55.

1894. _Craterium citrinellum_ List., _Mycetozoa_, p. 74.

1899. _Physarum caespitosum_ Schw., Macbr., _N. A. S._, p. 37.

1911. _Physarum citrinellum_ Peck, List., _Mycetozoa, 2nd ed._, p. 62.

Sporangia gregarious, or scattered globose, short-stipitate, pale yellow or ochraceous, smooth or slightly roughened by the presence of minute lime-particles; peridium more or less distinctly double, the outer calcareous, fragile, the inner very delicate, with here and there a calcareous thickening, ruptured irregularly; stipe very short, half the sporangium, fuliginous, furrowed, expanded below into an imperfectly defined hypothallus; capillitium abundant, the nodes stellate-angular, large, the internodes delicate, short; spore-ma.s.s black, spores violaceous-brown by transmitted light, strongly spinulose, 10-12.5 .

A very distinct and handsome species. Easily recognizable at sight by its large, globose, almost sessile and yet distinctly stalked sporangia.

The color to the naked eye is pale ochraceous or buff. Only under a moderate magnification do the citrine tints come out.

In the _Twenty-second N. Y. Report_, Dr. Peck incorrectly referred this species to _Physarum citrinum_ Schum. On the appearance of Rostafinski's _Monograph_, Dr. Peck in his revised list, _l. c._, writes _P.

citrinellum_ Peck, with description on p. 57, following. Under the last name the species has been generally recognized in the United States and distributed. _N. A. F._, 2490.

In the former edition, this species was referred to _P. caespitosum_ Schw., of which the original description is as follows: "_P.

caespitosum_ L. v. S., pulcherrimum. In foliis et stipitibus Rhododendri, Bethlehem. Physarum substipitatum aut saltem basi attenuata, caespitosim crescens et sparsim. Caespitulis 3 linearibus; peridiis stipatis, turbinatis, ovatis, basi contracta membranula exterori luteosquamulosa aut punctato-squarrulosa. Sporidiis nigro-brunneis, floccis citrinis inspersis." _Synopsis N. A. Fungi_, 2301.

The type from the Schweinitz herbarium is no longer in evidence. Without it, the reference cannot be sustained.

Not uncommon in the eastern United States; reported also from j.a.pan.

45. PHYSARUM ALBESCENS _Ellis._

PLATE XVI., Figs. 4, 4 _a_.

1889. _Physarum albescens_ Ellis _in litt_: not described.

1893. _Physarum auriscalpium_ Cke., Macbr., _Bull. Lab. N. H. Iowa_, No. 2, p. 155, in part.

1894. _Physarum virescens_ var. _nitens_ List., _Mycetozoa_, p. 59, in part.

1899. _Physarum virescens_ var. _nitens_ List., Macbr., _N. A. S._, p. 34, in part.

1899. _Leocarpus fulvus_ Macbr., _N. A. S._, p. 82.

1911. _Physarum fulvum_ Lister, _Mycet., 2nd ed._, p. 60.

1911. _Physarum virescens, nitens_ List., _Mycet., 2nd ed._, p. 84, in part.

Sporangia gregarious, scattered, ovoid or globose, pale yellowish or fulvous, opening irregularly above, stipitate; the peridium double, the outer layer more or less calcareous, the inner delicate, almost indistinguishable, persistent below as a shallow cup; the stipe long, weak, striate, fulvous or yellow; hypothallus distinct, venulose, or more or less continuous; capillitium pallid or white, dense, with here and there below large continuous yellow calcareous nodules; columella none; spore-ma.s.s black; spores by transmitted light, dark brown, rough, 13-15 . Varies to forms with single (inner) peridium and simple physaroid capillitium. _Vid._ descriptions cited for _P. auriscalpium_, _P. nitens_, etc.

This interesting form is from our western mountains, and suggests at first a diderma; but the capillitium is entirely unlike that of a diderma in color and structure, and plainly belongs here. Plasmodium yellow, on fallen leaves and twigs. Our material is from Prof. Bethel, Denver; and Lake Tahoe, Nevada; later from Dr. Weir, Montana. No doubt common at high alt.i.tudes near the snow-line in mountainous regions, probably around the world.

As indicated above, this was originally entered as of the genus _Leocarpus_; the taxonomic history of the form may interest readers who note with surprise the presentation in synonymy here developed.

About thirty-five or forty years ago Dr. Harkness of California sent to Mr. Ellis of New Jersey a slime-mould which the sender referred to _Diderma albescens_ Phillips, (_Grev._ V., p. 114, 1877). Ellis sent a small bit to the Iowa herbarium without other comment, save that he thought it a physarum. Sometime later Mr. Ellis received from Father Langlois, a correspondent in Louisiana, specimens he esteemed the same thing. He expressed the opinion that if this were what Phillips had found in California, it should perhaps be called a physarum. The Louisiana material by his courtesy came also to this table. The material was scanty, in poor condition, and all waited further light. To these specimens the writer paid less attention. They were in the hands of his correspondents and the courtesy of the case required their further consideration by Dr. Rex.

In 1889 Mr. Holway found in Iowa, a physarum of which he sent part to Ellis and the remainder to the writer who, then engaged on the _Myxomycetes of East. Iowa_, referred his part of this Iowa gathering to the _Physarum auriscalpium_ Cke. as found in New York. Under this caption a specimen was later sent to Mr. Lister, who has, as we see, consistently regarded the thing as a variety of _P. virescens_ Ditmar, _P. nitens_ List.

Meantime in 1898 Colorado material from Professor Bethel reached the University. This did not recall any of the materials sent from Ellis.

_Diderma albescens_ had meanwhile come again from California, and been recognized as _Diderma niveum_ Rost.

Accordingly, in _N. A. S._ the latest arrival from Colorado was described as a new species, and with some temerity perhaps, offered as a second species of the hitherto monotypic _Leocarpus_, all on account of the peculiar capillitium. Sometime after publication our most valued correspondent Mr. Bilgram called attention to the resemblance between the Colorado and Louisiana material already referred to. The University specimens as stated were small, broken, and in every way poor, but enough remained to indicate the evident justice of our correspondent's suspicion. Further investigation of the Holway material in Philadelphia showed that _it too was ent.i.tled to consideration_! Inasmuch as the Holway sending was all from one plasmodium, all difficulties vanished at once. The Iowa gathering showed two phases: one at the University represents _P. nitens_, physaroid, single-walled; while the Philadelphia part of the gathering corresponds, poorly it is true, but in fact, as _now_ appears, to the form coming in perfection from Colorado; leocarpine in structure, published as _Leocarpus fulvus_; _P. fulvum_ Lister. Since the combination _P. fulvum_ is already in use, synonym of _P. rubiginosum_, it seems better to write the name suggested by Ellis; _Physarum albescens_ never having been published, because _Diderma albescens_, as noted took care of itself.

Since Rostafinski we separate all these physaroid forms chiefly by capillitial characters: capillitial structure separates genera.

_Physarum diderma_ is a physarum despite its double wall. And so here _Leocarpus_ was set out by its differentiating capillitium. In good specimens of the present species a large part of the capillitial net is entirely free from lime, so that when the peridium first opens at the summit, sometimes no trace of lime appears; the calcareous deposits are below, and tend to occupy not the nodal intersections as in _Physarum_, but in large ma.s.ses involve portions of the net itself, nodes and all, as in _Leocarpus_. Miss Lister's beautiful figures, _op. cit._, Figs. 66 and 82, show this very well.

In The _Journal of Botany_, 52, p. 100, the distinguished author and artist records the discovery of this species in the mountains of Switzerland. She says: "This specimen shows a striking resemblance to _Leocarpus fragilis_ Rost., both in the shape of the sporangia and in the capillitium and spores; but although the color of the sporangia varies in both these species, the walls of _P. (L.) fulvum_ are membranous and rugose with included deposits of lime granules and show nothing of the polished cartilaginous layers characteristic of _L.

fragilis_."

The species is a boundary type at best, and shows again how artificial all our taxonomy is apt to prove, when the number of presentations of some particular type becomes larger.

For these reasons, the present author writes _Physarum_, and believes the question of ident.i.ty in a perplexing case fortunately settled.

46. PHYSARUM VARIABILE Rex.

1893. _Physarum variabile_ Rex, _Proc. Phil. Acad._, p. 371.

1911. _Physarum variabile_ Rex, List., _Mycetozoa, 2nd ed._, p. 47.

Sporangia scattered, stipitate, sub-stipitate or sessile, about 1 mm.

high; regularly or irregularly globose, ellipsoidal, obovate or cylindric-clavate in shape; sporangium wall sometimes apparently thick, of a dingy yellow or brownish-ochre color, slightly rugulose on the surface, crustaceous, brittle, rupturing irregularly, sometimes thin, translucent, covered externally with flat circular calcic-ma.s.ses falling away in patches; stipes nearly equal, occasionally much expanded at the base, rough, longitudinally rugose, variable in size, sometimes one-third of a millimetre high, sometimes a mere plasmodic thickening of the base of the sporangium; color of stipes varying from a yellowish-white to a dull brownish-gray; capillitium a small-meshed network of delicate colorless tubules with large, many-angled, rounded ma.s.ses of white, or rarely yellowish-white lime-granules at the nodes; no true columella, but often a central irregular ma.s.s of white lime-granules; spores dark violet-brown, verruculose, 9-10 .

Pennsylvania. _Dr. Rex._

Lister, _op. cit._, describes a variety, _sessile_, presenting plasmodiocarpous fructification, from Ceylon, also from Antigua, but there are some doubts as to the ident.i.ty of these with American sessile and plasmodiocarpous forms. Vid. _Jour. Bot._ x.x.xVI., p. 113.

47. PHYSARUM AURISCALPIUM _Cooke_.

1877. _Physarum auriscalpium_ Cooke, _Myx. U. S._, Am. Lyc. Nat. Hist.

N. Y., XI., p. 384.

1877. _Physarum auriscalpium_ Cke., _Myx. Gr. Brit._, Pl. 24, f. 253-4.

1893. _Physarum sulphureum_ (Alb. & Schw.), Sturgis, _Bot. Gaz._, XVIII., p. 197.

1898. _Physarum auriscalpium_ Cke., List., _Jour. Bot._, x.x.xVI., p. 115.

1911. _Physarum auriscalpium_ Cke., List., _Mycetozoa, 2nd ed._, Syn. excl.

Sporangia scattered, stipitate or occasionally sub-sessile spherical, .8-1 mm. high; peridium granulated, bright golden yellow; stipe, when present, one-half to two-thirds the height of the sporangium, blackish-brown; hypothallus, minute, thin, brown; columella absent; capillitium rather dense, composed of large angular nodes, completely filled with bright yellow granules of lime, and connected by very short, delicate, colorless internodes dest.i.tute of lime; spores globose minutely verruculose, or asperate, 10.7-11.8 in diameter, brownish-violet by transmitted light, black in the ma.s.s.

This is the original description, 1893, of _P. sulphureum_ (Alb. & Schw.) Sturgis; the author last named having compared certain stalked New England forms with what he could find of _P. sulphureum_ in the herbarium of Schweinitz at Philadelphia, and having, as he thought, established ident.i.ty.

Meantime Mr. Lister had been inclined to refer _P. auriscalpium_ Cke. to _P. rubiginosum_ Fr., _Mycetozoa_, p. 61.

In 1898 Professor Sturgis and Mr. Lister agreed that the New England specimens, owing to color and character of stipe and some other differences could not be the Schweinitzian species, but did indeed conform much better with those in London labelled _P. auriscalpium_ Cke.

Accordingly _P. sulphureum_ is something else, very different, (v. A. & S., Cons. _Fung. Tab._, VI., f. 1), and by aid of recent[28] discoveries in Sweden goes its own way again. Meanwhile _P. sulphureum_ Sturgis stands, a new type for _P. auriscalpium_ Cke., the description modified to suit; the lamented pioneer-author receives honor due, and his handsome species, with its "golden graving," may now march, let us hope, under appropriate banner far down the fair highway to future fame!

48. PHYSARUM OBLATUM _Macbr._

PLATE III., Fig. 6; PLATE XIV., Figs. 3, 3 _a_, 3 _b_.

1879. _Physarum ornatum_ Peck, Rep. _N. Y. Museum_, x.x.xI., p. 40 (?).

1893. _Physarum oblatum_ Macbr., _Bull. Lab. Nat. Hist. Iowa_, II., p. 384.

1896. _Craterium maydis_ Morg., _Myx. Miam. Vall._, p. 87.

1909. _Physarum maydis_ Torr., _Flor. des Myxo._, p. 193.