1911. _Physarum maydis_ Torr. List., _Mycet., 2nd ed._, p. 59.

Sporangia gregarious, stipitate, small, bright yellow, globose or depressed-globose, rough; stipe reddish-brown or fuliginous, even, short, slender; hypothallus scant, black, or none; columella none; threads of the capillitium yellow, delicate, connecting the rather dense and abundant yellow lime-granules; spore-ma.s.s brownish-black, spores violaceous, minutely but distinctly spinulose, 9-11 .

This species is easily recognizable by its brilliant yellow color, somewhat rugose, sometimes scaly peridium, its richly calcareous capillitium, also bright yellow where not weathered or faded, its dark brown, translucent, non-calcareous stem. In dehiscence, the base of the peridium in cup-form, sometimes persists. This circ.u.mstance, with the fact that decaying maize-stalks and leaves are a favorite habitat, led Professor Morgan to its description as _Craterium maydis_. But it is doubtless a physarum, occurring on habitats of all sorts, from Ohio to Iowa, Colorado and Washington. Ceylon(?).

_Physarum ornatum_ Peck is doubtfully cited here, although Professor Morgan thought it the same as _P. oblatum_. As a matter of fact the original brief description, _op. cit._, does not suggest either _P.

oblatum_ or _P. maydis_; rather a form of _Tilmadoche viridis_.

Professor Sturgis, _Notes on Some Type Specimens of Myxo., in the N. Y.

Museum, Trans. Conn. Acad. Arts and Sci._, Vol. X., Pt. 2, p. 470, says that of the type almost nothing remains, that the name _P. ornatum_ Pk.

"should be discarded."

49. PHYSARUM GALBEUM _Wing._

1890. _Physarum galbeum_ Wing., Ell., _N. A. F._, 2491 (no description).

1892. _Physarum petersii_ Berk. & C., Ma.s.s., _Mon._, p. 296, in part.

1894. _Physarum berkeleyi_ Rost., List., _Mycetozoa_, p. 48, in part.

1899. _Physarum galbeum_ Wing., Macbr., _N. A. S._, p. 53.

1911. _Physarum galbeum_ Wing., List., _Mycetozoa, 2nd ed._, p. 59.

Sporangia scattered, globose, stipitate, often nodding, golden yellow, the peridium exceedingly thin, breaking up into patches on which the yellow lime granules are conspicuous; stipe non-calcareous, pale brown or amber-colored, longitudinally wrinkled, about one and one-half times the diameter of the peridium; columella none; hypothallus none; capillitium dense, extremely delicate, the nodes only here and there calcareous, the lime knots when present small, angular, yellow; spore-ma.s.s pale brown; spores almost smooth, lilac- or violet-tinted, 7.5-10 .

Distinguished among the small delicate species with which it will be naturally a.s.sociated, by the yellow, richly calcareous wall of the globose sporangium and the almost limeless capillitium. The stipe is hollow and contains irregular ma.s.ses of refuse granular matter, but no lime so far as we have been able to discover. _P. flavicomum_, to which the species is related most closely, differs in having the wall non-calcareous, iridescent, as well as in the color throughout; the character of the capillitium, in which lime is abundant; the absence of refuse-matter in the stem.

Pennsylvania, Iowa, Minnesota.

50. PHYSARUM TENERUM _Rex._

1890. _Physarum tenerum_ Rex., _Proc. Phil. Acad._, p. 192.

1894. _Physarum polymorphum_ Rost. var. _obrusseum_, Lister, _Mycet._, p. 48.

1899. _Physarum obrusseum_ (Berk. & C.) Rost., Macbr., _N. A. S._, p. 52.

1911. _Physarum tenerum_ Rex., List., _Mycetozoa, 2nd ed._, p. 52.

The peridium thin, membranaceous, thickly studded with circular, flattened, yellow granules of lime; stipe long, slender, subulate, opaque, pale brown, striate and black below, pale yellow above; columella none; capillitium yellow or white, delicate, forming a loosely but regularly meshed network with numerous small round or rounded granules at the intersections; spores dark brown, delicately warted, 7-8 .

This delicate physarum, very fragile and evanescent, seems to be distinct, by reason of its characteristic rounded lime granules, from any similar, stipitate species. It varies a little according to locality. Ohio specimens are a little larger and have thicker and more calcareous stipes than is usual in those from Philadelphia. The walls of the sporangia when fully matured generally break into several petal-like segments which finally become reflexed. The description given by Berkeley is entirely insufficient.

In an earlier edition this species was entered as _P. obrusseum_ following the Polish text. Miss Lister who has the type of _Didymium obrusseum_ at hand considers it as representing a phase of _Physarum polycephalum_ Schw. _D. tenerrimum_ Berk. & Curt. is judged the same.

_P. tenerum_ Rex is, in any event, certain, and the combination is adopted.

Rare:--Pennsylvania, Ohio, Louisiana, Texas, Iowa, Portugal, j.a.pan.

51. PHYSARUM FLAVICOMUM _Berk._

PLATE XV., Figs. 3, 3 _a_.

1845. _Physarum flavicomum_ Berk., _Hook. Jour. Bot._, IV., p. 66.

1873. _Physarum cupripes_, Berk. & Rav., _Grev._, II., p. 65.

1875. _Physarum berkeleyi_ Rost., _Mon._, p. 105.

1894. _Physarum berkeleyi_ Rost., List., _Mycetozoa_, p. 57.

1899. _Physarum flavicomum_ Berk., Macbr., _N. A. S._, p. 53.

1911. _Physarum flavicomum_ Berk., List., _Mycetozoa, 2nd ed._, p. 58.

Sporangia gregarious, small, spherical, at first fuliginous throughout, stipitate; the peridium thin, dest.i.tute of lime, iridescent, breaking up and deciduous in patches, except at the base; stipe twice the diameter of the peridium, brown, fluted, not hollow, tapering upward from a small but distinct, radiant hypothallus; columella none; capillitium dense, persistent, the nodes frequently calcareous, elongate and vertical, especially below, yellow; spore-ma.s.s brown; spores by transmitted light, bright violaceous-brown, slightly papillose, 9-10 .

This species is instantly distinguishable from all cognate forms by its peculiar sooty color. Not less is the species structurally marked by its capillitium. The latter below is exactly as in the species of _Tilmadoche_. Indeed, the present species unites characters supposed to distinguish _Physarum_ from _Tilmadoche_, and would so far justify those authors who bring all the species of both genera together under one generic name. In any case the species is by its capillitium entirely distinct from _P. galbeum_, as well as by the structure of the stipe and the peridial surface. The plasmodium, at first watery, emerges from decayed elm logs and soon takes on a peculiar greenish tint preserved somewhat in the mature fruit.

Rostafinski, _Monograph_, pp. 105, 106, rejects Berkeley's specific name, _flavicomum_, because it refers to the somewhat indefinite, characteristic color. As this is no valid reason for change, we have restored Berkeley's specific name, which by general consent has priority. _N. A. F._, 3299.

Not common. New Jersey, Ohio, South Carolina, Iowa.

52. PHYSARUM BETHELII (_Macbr._) _Lister_.

1899. _Tilmadoche bethelii_, Macbr., _Exempl. ad Herbaria._ 1911. _Physarum gyrosum_ Rost., List., _Mycetozoa, 2nd ed._, p. 75.

Sporangia scattered, globose, umbilicate below, .5-1 mm. in diameter, iridescent blue, or sometimes tinged by the presence of delicate pale yellow calcareous scales, stipitate; stipe rather short, black or dark brown, equal; capillitium dense, radiating from the black, slightly intrusive summit of the stipe, and from the base of the peridium ascending; the nodules not numerous, elongate, branching betimes, pale yellow; spores minutely roughened, 10-12 .

This beautiful delicately tinted little species is clearly tilmadochoid in the Friesian sense. The capillitium persists after the fall of the upper filmy peridium, adherent below to the persisting peridial base.

Collected thus far twice only; by Professor Bethel and by Professor Sturgis, Colorado.

SECTION 2

_=Tilmadoche= Fries_

53. PHYSARUM GYROSUM (_Rost._) _Jahn._

1875. _Physarum gyrosum_ Rost., _Mon._, p. 111.

1902. _Physarum gyrosum_ Rost., Jahn, _Ber. Deutsch. Bot. Ges._, XX., p. 272, t. XIII.

1911. _Physarum gyrosum_ Rost., List., _Mycetozoa, 2nd ed._, p. 75.

Sporangia gyrose, variable in form, or plasmodiocarpous and irregular, venulose, sessile upon a common, strongly developed hypothallus, sometimes isolated and irregularly globose, dehiscing irregularly or by longitudinal fissure, yellowish or greyish white; columella none; capillitium delicate, the nodules elongate, variable in size; spores pale violaceous, minutely spinulose, 7-10 .

This is a European species recently resuscitated by Dr. Jahn. It perhaps might more correctly be recorded as _P. gyrosum_ Jahn, since Rostafinski certainly attempted in his description to cover two apparently distinct things. He seems to have had before him _Fuligo muscorum_ Schw. and "_P.

gyrosum_," but he thought them the same, and his description touches now one, now the other. Since _F. muscorum_ Schw. has all along held its own and received due recognition, it is interesting to note the recovery of this gyrose form.

Judging by description and figures, it resembles a very large, sessile phase of _P. polycephalum_. See further under that species.

Europe, j.a.pan, Eastern United States (?).

54. PHYSARUM POLYCEPHALUM _Schw._

PLATE VIII., Figs. 2, 2 _a_, 2 _b_.