The North American Slime-Moulds Part 14

Sporangia distinct or plasmodiocarpous, the plasmodiocarp creeping in long vein-like reticulations or curves, laterally compressed; sometimes distinct and crowded, always sessile. Peridium double; the outer thick, calcareous, fragile, snow-white; the inner delicate, the dehiscence by more or less regular longitudinal fissure. Capillitium strongly developed with abundant white, calcareous granules. Spores smooth, dull violet, 8-9 . Plasmodium pale gray, or nearly white.

Easily recognized at sight by its peculiar form, bil.a.b.i.ate and sinuous.

Apart from microscopic structure, perfectly described by Fries, _Syst.

Myc._, p. 145. Bulliard called it _Reticularia sinuosa_. Habitat various, but not infrequently the upper surface of the leaves of living plants, a few inches from the ground. The two sorts of fructification often occur side by side, or merge into one another from the same plasmodium. Where the substratum affords room the plasmodiocarpous style prevails; in narrower limits single sporangia stand. The calcareous deposit on the peridium is usually very rich and under a lens appears made up of countless snowy or creamy flakes. Forms occur, however, in which these outer calcic deposits are almost entirely wanting; the peridium becomes transparent, the capillitium visible from without.

Judging from material before us, this appears to be the common presentation in western Europe. See also No. 5 following.

Widely distributed. New England to the Carolinas, and Louisiana west to South Dakota and Nebraska, Iowa and Washington.

5. PHYSARUM BITECTUM _List._

PLATE XIX., Fig. 16.

1891. _Physarum diderma_ Rost., List., _Jour. Bot._, XXIX., p. 260.

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

1911. _Physarum bitectum_ List., _Mycetozoa, 2nd ed._, p. 78.

Sporangia gregarious, sub-globose, sessile or plasmodiocarpous, smooth white or pallid, terete or somewhat compressed; peridium double, the outer wall calcareous, free and deciduous above, recurved and persistent below; the inner, smooth, pale purplish, more persistent; dehiscence more or less irregular beginning at the top; capillitium of large white nodules connected by short hyaline threads; spores generally spinulose, violaceous brown, 9-10 .

As suggested by the author of this species it is properly a variety of _P. sinuosum_; certainly is, as it presents itself in this part of the world. Of the species last named we have compressed forms opening by narrow fissure along their knife-edged summit, with scarce place for capillitium at all between the approaching walls; again we have colonies of sporangia quite terete, calcareous without, opening in fragmental fashion at the top, displaying sometimes the thin membranous inner wall but at length fissured and gaping as in the more usual phase figured by authors, where the plasmodiocarp is simply compressed but not extravagantly thin. Both types occur in the western mountains, forms with and without calcium, fissured by wider or narrower cleft, _from the same plasmodium_; forms bil.a.b.i.ate and forms opening at first to display an inner peridium; forms globose with narrow base, but apex cleft, and forms ellipsoidal, yet compressed, opening like the gaping of some tiniest bivalve; did not Persoon say _P. bivalve_! all are bivalvular at the last! Nay; but what are these? Here are some of the shorter forms become suddenly obovate, and are actually mounted on _stipes_! Surely variation in the same plasmodium can no farther go![22]

Not rare. Colorado to the Pacific Coast. Evidently a western-American variation of Bulliard's European type. The latter occurs abundantly in Iowa on the sh.o.r.es of Lake Okoboji; otherwise not common.

6. PHYSARUM BOGORIENSE _Racib._

1898. _Physarum bogoriense_ Raciborski, Hedw., x.x.xVII., p. 52.

Sporangia sessile, elongate, creeping but not reticulate, semicircular in transverse section, sometimes globose or depressed globose; peridium double, the outer thick coriaceous, yellow or brown, dehiscing stellately into persistent more or less triangular reflected lobes, remote from the thin, colorless inner wall; columella none; capillitium feebly developed, the nodes white, large, isodiametric; spores bright violet, smooth, 7-8 .

This species is not uncommon in the mountains of Colorado where it has been taken at various stations by Bethel. It is reported from Pennsylvania and South Carolina. Raciborski describes it from Java.

In habit it is very much like some forms of _P. sinuosum_ but differs in the depressed, rather than compressed sporangia, and in the brown color of the outer peridium.

7. PHYSARUM ALPINUM _G. List._

1910. _Physarum alpinum_ G. Lister, _Jour. Bot._, XLVII, p. 73.

Sporangia globose and sessile or plasmodiocarpous, dull yellow, smooth or scaly; peridium double, the outer wall densely calcareous, separating irregularly from the membranous inner wall; capillitium densely calcareous, the nodes large, more or less branched, yellow; spores purple brown, closely and minutely warted, 9-14 .

This species is based by its author upon a gathering made in California by Dr. Harkness and named by Phillips who received it in England, _badhamia inaurata_. He seems not to have described it. Since its first appearance, the form has been found repeatedly in the Juras. Specimens are before me from Mt. Rainier believed to be the same. The plasmodiocarpous habit and yellow capillitium separate this from related _P. contextum_ and _P. mortoni_.

Europe, California, Washington.

8. PHYSARUM DIDERMA _Rost._

PLATE XVIII., Fig. 9.

1875. _Physarum diderma_ Rost., _Mon._, p. 110.

1898. _Physarum didermoides_ var. _lividum_ List., _Jour. Bot._, x.x.xVI., p. 162.

1899. _Physarum diderma_ Rost., Macbr., _N. A. S._, p. 30.

1911. _Physarum testaceum_ Sturgis, List., _Mycetozoa, 2nd ed._, p. 79.

Sporangia snow-white, cl.u.s.tered, sessile or narrowly adnate, globose or polygonal by mutual compression; peridium double, the outer dense, fragile, thick, calcareous, the inner delicate, remote, translucent, capillitium well developed, the calcareous nodules white, rounded or angular, sometimes uniting to form a pseudo-columella; spore-ma.s.s black; spores purplish, distinctly rough, 10-12 .

A beautiful and distinct species. As others in the group with which it is here a.s.sociated, it is a physarum with the outward seeming of a diderma. It occurs in Europe, therefore it is safe to a.s.sume that Rostafinski saw it. So well marked it is that any good description will define it, and Rostafinski describes it perfectly, adequately.[23]

Mr. Lister having used for another species the name we here apply--see under _P. bitectum_--referred this present form to _P. didermoides_ Rost., _l. c._ Professor Sturgis, convinced that such reference was at least doubtful, gave to our American gatherings the distinctive name above, citing specimens from Ma.s.sachusetts, from Colorado, and from California. Curiously enough he also includes specimens of _R.

didermoides_ var. _lividum_ List., sent from England!

Rare! Certainly rare in Europe and so far seldom seen in the United States, though widely distributed. Specimens are before us from Ohio, Michigan, Iowa, Oregon. No doubt the mountains of the north Pacific coast, a region to-day almost unsearched, will yet afford the species in abundance.

As stated Mr. Lister first applied the name _P. diderma_ to a plasmodiocarpous form occurring in England and near _P. sinuosum_. More lately, _Mon., 2nd ed._, p. 78, he adopts a new specific name, _P.

bitectum_ for the English specimens, and enters _P. diderma_ as a probable synonym for _P. lividum_ R. Evidently our present form as described above has not come to Mr. Lister's view. He says the original type is not to be consulted.

There is really no more merit in this later comparison than in that discarded. The species _P. diderma_ is not _P. lividum_, but stands as originally delimited, and will, doubtless, some day yet again appear in its own behalf upon the witness-stand of time; when, as before, a Frenchman in DeBary's old-time haunts may rise to give it welcome, brought back by some keen-eyed Polish student eager now in the arts of peace, from Warsaw's shady groves.

9. PHYSARUM CONTEXTUM _Persoon._

PLATE IX., Figs. 3 and 3_a_.

1796. _Diderma contextum_ Persoon, _Obs. Myc._, I., p. 89.

1801. _Physarum contextum_ Persoon, _Syn. Meth._, p. 168.

1829. _Diderma contextum_ Persoon, Fries, _Syst. Myc._, III., p. 111.

1873. _Diderma ochroleuc.u.m_ Berk. & C., _Grev._, II., p. 52.

1879. _Diderma flavidum_ Pk., _N. Y. Rep. State Mus._, x.x.xI., p. 55.

Sporangia distinct, sessile, densely crowded, sub-rotund reniform more often elongate, interwoven; peridium double; the outer rather thick, calcareous, yellow, or yellowish white, the inner thin, yellowish; capillitium white, containing numerous large, irregular calcareous granules; columella none; spores deep violet, 11-13 , covered with minute spinules.

This singular species occurs not rarely upon the bark of fallen twigs, upon bits of straw or gra.s.s-stems lying undisturbed upon the ground. In such a position the slime-mould covers, as with a sheath, the entire substratum. The outer peridium, especially its upper part, is entirely evanescent, our Fig. 3 shows the sporangia with upper outer peridium wanting. Not rare in summer and autumn.

New England, New York, Pennsylvania, Ohio, Wisconsin, Illinois, Iowa, Colorado, Oregon, Nicaragua.

10. PHYSARUM CONGLOMERATUM (_Fr._) _Rost._

1803. _Spumaria granulata_ Schum., _Enum. Pl. Saell._, II., p. 196, No. 1419.

1803. _Spumaria minuta_ Schum., _l. c._ 1829. _Diderma granulatum_ Schum., Fries, _S. M._, III., p. 110.

1829. _Diderma minutum_ Schum., Fries, _l. c._, p. 111.

1829. _Diderma conglomeratum_ Fries, _l. c._, p. 111.

1875. _Physarum conglomeratum_ (Fr.) Rost., _Mon._, p. 108.

1892. _Physarum rostafinskii_ Ma.s.see, _Mon._, p. 301.

1894. _Physarum conglomeratum_ Rost., Lister, _Mycetozoa_, p. 58.

1899. _Physarum conglomeratum_ (Fr.) Rost., Macbr., _N. A. S._, p. 31.

1911. _Physarum conglomeratum_ Rost., List., _Mycetozoa, 2nd ed._, p. 80.