1822. _Physarum polycephalum_ Schw., _Syn. Fung. Car._, No. 382.

1829. _Didymium polycephalum_ (Schw.) Fries, _Syst. Myc._, III., p. 122.

1837. _Didymium polymorphum_ Mont., _Ann. Sci. Nat._, Ser. 2, 8, p. 361.

1837. _Didymium gyrocephalum_ Mont., _op. cit._, p. 362.

1875. _Physarum polymorphum_ (Mont.) Rost., _Mon._, p. 107.

1875. _Tilmadoche gyrocephala_ (Mont.) Rost., _Mon._, p. 131.

1899. _Tilmadoche polycephala_ (Schw.) Macbr., _N. A. S._, p. 57.

1911. _Physarum polycephalum_ Schw., List., _Mycetozoa, 2nd ed._, p. 58.

Sporangia spherical or irregular, impressed, gyrose-confluent, helvelloid, umbilicate below; peridium thin, ashy, covered with evanescent yellow squamules, fragile; stipe from an expanded membranaceous base, long-subulate, yellow; spores smooth, violet, 9-11 .

A most singular species and well defined is this, occurring in ma.s.ses of decaying leaves or on rotten logs. The plasmodium at first colorless; as it emerges for fructification, white, then yellow, spreading far over all adjacent objects, not sparing the leaves and flowers of living plants; at evening slime, spreading, streaming, changing; by morning fruit, a thousand stalked sporangia with their strangely convoluted sculpture. The evening winds again bear off the sooty spores, and naught remains but twisted yellow stems crowned with a pencil of tufted silken hairs. August.

Although Rostafinski's description of this species is accurate and marks exactly a _Tilmadoche_ and is very different from his description of _Physarum polymorphum_, nevertheless it is probable that both descriptions have reference to the same thing. All specimens on which both species were based were American; _P. polymorphum_, North American.

But the only North American form to which reference can be made is that by Schweinitz called _P. polycephalum_ and, fortunately, sufficiently described. Furthermore, Rostafinski, under _T. gyrocephala_, himself affirms the probable ident.i.ty of Montagne's _Didymium gyrocephalum_ with the Schweinitzian species, and uses Montagne's specific name provisionally. For these reasons it seems proper to write the species as above.

Widely distributed and common, from Maine and Canada to Nebraska, and Washington and south to Nicaragua.

This species is so common that its plasmodium and fructification may be easily observed. Professor Morton E. Peck, who has been for years a close observer of the vegetative phases of our Iowa species, says of _P.

polycephalum_: "In one instance I observed a plasmodium for twelve successive days on the surface of a decaying stump. During this period it crept all around the stump and from top to bottom several times. At one time the color was bright yellow; at another, greenish yellow; and once, shortly before fruiting, it became clear bright green. A heavy rain fell upon the plasmodium but it appeared to sustain little injury and ultimately developed normal sporangia."

55. PHYSARUM NUTANS _Pers._

1791. _Sphaerocarpus albus_ Bull., _Champ._, p. 137, t. 407, III., and t. 470, I, A-L.

1791. _Stemonitis alba_ (Bull.), Gmel., _Syst. Nat._, p. 1469 (?).

1795. _Physarum nutans_ Pers., _Ust. Ann. Bot._, XV., p. 6.

1803. _Trichia cernua Schum., Enum. Pl, Saell._, II., p. 241.

1829. _Physarum cernuum_ (Schum.) in part, Fr., _Syst. Myc._, III., pp. 130, 147.

1848. _Tilmadoche cernua_ (Schum.) Fr., _Summ. Veg. Sc._, p. 454.

1873. _Tilmadoche nutans_ (Pers.) Rost., _Versuch_, p. 10.

1899. _Tilmadoche alba_ (Bull.) Macbr., _N. A. S._, p. 58.

1911. _Physarum nutans_ Pers., List., _Mycet., 2nd ed._, p. 67, in part.

Sporangia gregarious, depressed-spherical, stipitate, umbilicate, gray or white, thin-walled, nodding; stipe long, tapering upward, brown or black below, ashen white above, lightly striate, graceful; capillitium abundant, threads delicate, intricately combined in loose persistent network with occasional minute, rounded, or elongate calcareous nodules; spores minutely roughened, globose, about 10 .

The nodding, lenticular, umbilicate sporangium, barely attached to the apiculate stipe, is sufficient to distinguish this elegant little species, recognized and quite aptly characterized by mycologists for more than one hundred years. As _Sphaerocarpus albus_ Bulliard first prescribed the limits by which the species is at present bounded. The description by Fries (_Syst. Myc.,_, III., 128) is especially graphic; "Peridium very thin, in form quite constantly lenticular, umbilicate at base, at first smooth then uneven, generally laciniate-dehiscent, the segments persistent at least at base."

The stipe is usually white above, fuscous below, at the apex almost evanescent; hence the cernuous sporangia. The same character is less strikingly manifest in the species next following.

The plasmodium is bright yellow, sometimes greenish. Brought in from the field and maturing under a bell-jar, the color changes to a watery white just before the sporangia rise in fruit. _P. alb.u.m_ f.u.c.kel, _Rhen. Fl._, No. 1469, 1865, is believed to be _P. cinereum_ (Batsch) Pers.

Persoon changed Bulliard's specific name in this case to furnish one himself, more descriptive as he thought and distinctive. His success in this attempt must be esteemed but partial since all the related forms, immediately listed, _nod_ as well. Bulliard's name as applied by Persoon is therefore to be preferred. But the transfer from _Tilmadoche_ to _Physarum_ loses for us one step in the ladder of priority. _P. alb.u.m_ (Bull.) may not enter here, since Fries has given us one species under that t.i.tle. So Persoon comes next on the list, all the world now nodding approbation, let us hope!

Under the name _Physarum gracilentum_, Fries cites an extremely delicate form of this species. The sporangia are of the most minute, about .2-.3 mm. in diameter, globose, slightly umbilicate below, the stipe usually white at top, but sometimes black throughout. This graceful form occurs rarely in undisturbed woods.

Widely distributed in the eastern United States, apparently rare in the west. Reported from various parts of the world; Europe, j.a.pan, Australia, etc.

56. PHYSARUM VIRIDE (_Bull._) _Pers._

PLATE VIII, Figs. 8, 8 _a_, 8 _b_.

1791. _Sphaerocarpus viridis_ Bull., _Champ._, t. 407, Fig. I.

1791. _Sphaerocarpus luteus_ Bull., _Champ._, t. 407, Fig. II.

1791. _Sphaerocarpus aurantius_ Bull., _Champ._, t. 484, Fig. II.

1791. _Stemonitis viridis_ (Bull.) Gmel., _Sys. Nat._, p. 1469.

1794. _Physarum aureum_ Pers., Romer, _Neu. Mag. f. die Bot._, I., p. 88.

1795. _Physarum viride_ Pers., Usteri, _Ann. Bot._, XV., p. 6.

1801. _Physarum aurantium_ Pers., _Syn. Meth._, p. 173.

1829. _Physarum nutans_ var. Fries, _Syst. Myc._, III., pp. 128-129.

1875. _Tilmadoche mutabilis_ Rost., _Mon._, p. 129.

1880. _Tilmadoche viridis_ (Bull.) Sacc., _Michelia_, II., p. 263.

1894. _Physarum viride_ Pers., List., _Mycetozoa_, p. 50.

1899. _Tilmadoche viridis_ (Bull.) Sacc., Macbr., _N. A. S._, p. 59.

1911. _Physarum viride_ Pers., List., _Mycetozoa_, 2nd ed.

Sporangia globose, flattened or lenticular, beneath plane or concave, variously colored, yellow, greenish yellow, rusty orange, stipitate, nodding; the peridium splitting irregularly or reticulately; stipe variable in length and color, through various shades of red and yellow, subulate; capillitium strongly developed, concolorous with sporangium, the tubes with colorless or yellow calcareous thickenings; spores smooth, fuscous or violet-black, 8 .

A very handsome and rather common little species; like the preceding, but generally greenish-yellow in color, and occasionally brilliantly orange without a suggestion of green. Indeed, the color is so variable that some authors have been disposed to discard the species entirely, inasmuch as the chief specific character is color. The plasmodium is pale yellow, in rotten logs, stumps, etc. In the paler yellow or greenish forms the stipe is more commonly black.

This is _Physarum luteum_ (Bull.) Fries, and likewise also includes the three varieties, _viride_, _aureum_, _coccineum_, listed by the same author under _P. nutans_, while he at the same time remarks that they might with equal propriety be elsewhere referred. Rostafinski considers that all the colored forms agree in capillitium sufficiently to be a.s.sociated under one name and are in the same way unlike _T.

nutans_.[29] Rostafinski thinks to avoid confusion by suggesting a more fitting specific name, _T. mutabilis_, but there seems no good reason for not adopting the earliest identifiable specific appellation, which in this case appears to be _viride_. The yellow phase is common in Iowa, resembles in size, color, stipe, _P. galbeum_ Wingate, but is instantly distinguishable by the capillitium. _N. A. F._, 1213.

Widely distributed specimens are before us;--from New England, New York, Pennsylvania, Maryland, Ohio, Nebraska, Iowa, California, Oregon, Canada, Nicaragua, Samoa, Alaska, India, etc.

=EXTRA-LIMITAL=[30]

PHYSARUM MUTABILE (_Rost._) _List._

1875. _Crateriachea mutabilis_ Rost., _Mon._, p. 125.

1892. _Crateriachea mutabilis_ Rost., Ma.s.s., _Mon._, p. 344.

1894. _Physarum cinereum_ List., _Mycetozoa_, p. 55, in part.

1895. _Physarum crateriachea_ List., _Jour. Bot._, x.x.xIII., p. 323.

1910. _Physarum crateriachea_ List., Petch, _Mycetozoa Ceylon_, p. 336.

1911. _Physarum mutabile_ List., _Mycetozoa, 2nd ed._, p. 53.

Sporangia cylindrical ovoid or sub-globose white, plasmodiocarpous, sessile or stipitate, stipes when present yellow, with or without lime, often connected by a hypothallus; peridium thin, squamulose; capillitium persistent, intricate, the nodules white, more or less confluent at the center to form a real or a pseudo-columella; spores brownish-purple, spinulose, 7-8 .

Reported from Europe, Africa, Ceylon.

PHYSARUM ROSEUM _Berk. & Br._

1873. _Physarum roseum_ Berk. & Br., _Jour. Linn. Soc._, XIV., p. 84.

Plasmodium rose-red; sporangia gregarious, stipitate, globose, rose-red; the stipe erect, brown, rugulose, translucent; capillitium lax, delicate, lilac, the nodules few, large, purple-red, branching; spores reddish-lilac or brown, minutely spinulose, 7-10 .