The North American Slime-Moulds Part 15

Sporangia depressed, globose, or irregular, sessile, more or less aggregated, ochraceous-yellow, peridium double, the outer, thick, cartilaginous, at length irregularly ruptured, and reflexed, disclosing the more delicate, ashen-gray, inner membrane which encloses capillitium and spores; capillitium abundant, showing large, white irregular calcareous thickenings which are often consolidated in some sporangia tend to aggregate at the centre; spore-ma.s.s brown, spores violaceous, slightly roughened, 8-10 .

This beautiful species shows a peridium as distinctly double as in any diderma. The outer peridium is reflexed exactly as in some species of that genus; is yellow without, white within, and withal long persistent.

The capillitium of course distinguishes the species instantly as a physarum. By the size of the spores it is distinguished from the species preceding. This being a decisive specific character the synonymy prior to Rostafinski is somewhat uncertain. The specific name adopted by the Polish author is therefore approved, although perhaps not the earliest.

Rare. The only specimens thus far are from Tennessee and Louisiana.

11. PHYSARUM MORTONI _Macbr. n. s._

PLATE XX., Figs. 2, 2 _a_.

Sporangia gregarious, cl.u.s.tered but distinct, sessile small, about .75 mm., bright yellow, peridium double. The outer rough, breaking up into comparatively few rather large deciduous scales, the inner peridium white, calcareous, both persisting below to form a distinct cup; capillitium lax, the nodes white, large, angular; columella none; hypothallus none; spores distinctly rough, dark brown with the usual purple shadow, 10-12 .

A very distinct little species related, no doubt, to _P. contextum_, but different in habit. It is never crowded, shows no plasmodiocarpous tendencies, while the outer peridium is generally deciduous except at the base and falls in flakes.

Collected several times in the Three Sisters Mountains of Oregon by _Professor Morton E. Peck._

12. PHYSARUM BRUNNEOLUM (_Phillips_) _Ma.s.s._

PLATE XX., Figs. 7, 7 _a_.

1877. _Diderma brunneolum_ Phillips, _Grev._, V., p. 114.

1888. _Diderma brunneolum_ Phill., Saccardo, _Syll. Fung._, No. 1292.

1892. _Physarum brunneolum_ Phill., Ma.s.see, _Mon._, p. 280, Figs. 221-222.

1894. _Craterium pedunculatum_ Lister, _Mycetozoa_, p. 71.

1911. _Physarum brunneolum_ Ma.s.s., Lister, _Mycetozoa, 2nd ed._, p. 63, Pl. 69, Fig. _a_.

Sporangia scattered or gregarious, but not crowded, sessile, globose or sub-depressed; peridium double, thick, smooth or polished, yellow brown, stellately dehiscent, the segments reflexed, white within; columella none; capillitium dense, with nodes numerous, large irregular, internodes thin and short; spores globose, lilac, minutely warted, 6-7 .

This form was first described in _Grevillea_, V., p. 114, as _Diderma brunneolum_ Phillips. Later, students of the specimens preserved by Mr.

Phillips, concur that we have to do not with a diderma, but with a craterium, Lister, or physarum, Ma.s.see. There seems no reason why we should not respect the decision of Ma.s.see, whose description is here quoted in form somewhat abridged. The peridium is about as double as in the many physarums, not more so; the inner membrane so delicate as only occasionally to be revealed except to scrutiny most searching. But the appearance as a whole is as of some brown diderma; only the calcareous capillitium abides to prevent mistaken reference.

When opened by irregular dehiscence from above, the persisting cup-like base of the sporangium recalls _Leocarpus fragilis_; but then again the capillitium is different.

California, Portugal; Colorado,--_Sturgis._

13. PHYSARUM CINEREUM (_Batsch_) _Pers._

PLATE IX., Figs. 4, 4 _a_, 4 _b_.

1786. _Lycoperdon cinereum_ Batsch, _Elench. Fung._, p. 249, Fig. 169.

1801. _Physarum griseum_ Link, _Diss._, I, p. 27.

1805. _Physarum cinereum_ Persoon, _Synopsis_, p. 170.

1829. _Didymium cinereum_ Batsch, Fries, _Syst. Myc._, III., p. 126.

1829. _Physarum plumbeum_ Fries, _Syst. Myc._, III., p. 142.

1875. _Physarum cinereum_ Batsch, Rost., _Mon._, p. 102, in part.

1896. _Physarum plumbeum_ Fr., Morgan, _Myx. Mi. Val._, p. 98.

1899. _Physarum plumbeum_ Fr., Macbr., _N. A. S._, p. 35.

1909. _Physarum cinereum_ (Batsch) Pers., Torrend, _Flore des Myx._, p. 183.

Plasmodium watery white, or transparent, wide streaming on decaying sod, etc. Sporangia sessile, closely gregarious, or even heaped, sub-globose, elongate or plasmodiocarpous, more or less calcareous, gray; peridium simple, thin, more or less densely coated with lime; capillitium strongly developed, the nodes more or less richly calcareous, the lime-knots rounded, angular; spore-ma.s.s brown, spores clear violaceous-brown, 6-7, distinctly warted.

This delicate, inconspicuous species is well defined by the characters given. It occurs not rarely on richly manured ground, in meadows, lawns, or even on the open prairie. The plasmodium may form rings several inches in diameter, scattered here and there over a surface several square feet in extent, in fruit ascending the blades of gra.s.s, completely covering these with the crowded sporangia. The color of the fruit is well described in the specific name; gray or ashen gray. The spores are very distinctly papillate; in some specimens, however, almost smooth; in few instances, rough.

Common. New England west to the Black Hills and Pacific coast.

Cosmopolitan.

The present species well ill.u.s.trates the difficulty confronting the author of to-day who, discussing a group of microscopic organisms, would fain use the nomenclature of his predecessors, honored, but equipped with insufficient lenses. Here is a species reported common in Europe, observed by every mycologist there, from Micheli down, and yet awaiting adequate description until Rostafinski in his great book, gives the results of microscopic a.n.a.lysis. We are now really dealing with _P.

cinereum_ Rost; _P. cinereum_ Batsch is a compliment to certain rather clever water-color drawings.

Rostafinski gives a long list of synonyms, none, it is believed, represent American forms; and without taking careful thought, surely no one would rudely disturb such honorable interment; but, in his description the range of spore-measurement, 7-13.3 , gives us pause, and raises the suspicion that possibly, in one case or another, the sepulture were perhaps premature. The range is too great! Perhaps, in the series offered in confirmation, small-spored forms represent one species, large-spored, something else?

European students may decide this at their leisure. But Rostafinski having, not without much labor, practically completed his review of the physaroid forms had almost finished the last genus _Badhamia_, when his mind perhaps returned, no doubt with some lingering misgivings, to the thirteenth species in his physarum list. There were there, he recalled, some large-spored specimens which had rather badhamioid capillitium.

The sessile physarums of Fries were also before him, those especially, "floccis albis." Of these one shall be _B. panicea_, one _B. lilacina_ and one _B. verna_, described as having rather delicate colorless capillitial tubes combined in a loose net, the calcareous deposits about the enlarged intersections scanty, the spores 12.5 .

The description of the fructification as a whole is a condensed statement of that which describes _P. vernum_, and all taken together indicates some physarum. See now No. 3 preceding, p. 51.

_P. plumbeum_ Fr. belongs here. It has similar spores, the only difference is a less calcareous peridium and more scattered habit of fructification with more nearly regular, depressed-globose sporangia.

_P. cinereum_ Pers. as cited by Link, _op. cit._, is apparently a badhamia, may be _P. vernum_, while P. _griseum_ is probably the present species.

14. PHYSARUM VIRESCENS _Ditmar_.

PLATE VIII., Figs. 7, 7 _a_, 7 _b_.

1817. _Physarum virescens_ Ditmar, Sturm, _Deutsch. Fl. Pilze_, I., p. 123, Pl. 61.

1875. _Physarum ditmari_ Rost., _Mon., App._, p. 8.

1892. _Physarum ditmari_ Rost., Macbr., _Bull. Lab. Nat. Hist. 1a._, II., p. 155.

1894. _Physarum virescens_ Ditmar, Lister, _Mycetozoa_, p. 65.

1909. _Physarum virescens_ Ditmar, Torrend, _Flo. d Myx._, No. 207.

1911. _Physarum virescens_ Ditmar, Lister, _Mycetozoa, 2nd ed._, p. 83.

Sporangia sessile, crowded or heaped in small bunches, a dozen or more sporangia in one pile, spherical, ovoid or elongate, yellow or greenish yellow; peridium thin, fragile; capillitium delicate, with rather small, irregular, yellowish, calcareous nodes; columella none; spores bright violet, minutely roughened, 7-9 .

This species occurs more commonly on moss-tufts, with which it is frequently con-colorless, or escaped on dead leaves, etc. The peridium is flecked with calcareous scales or grains stained yellow or green, and to these the whole fruit owes its peculiar color. The color and aggregate, heaped sporangia are distinctive macroscopic characters.

In the _Monograph_, p. 113, Rostafinski adopted properly Ditmar's name for this species. Upon later consideration, in the _Appendix_, p. 8, he changed the name, writing _P. ditmari_, on the ground that _virescens_ was descriptive of a character to which the species in question occasionally refuses to conform. Most authors since Rostafinski have simply accepted his suggestion, so that the species is often entered _P.

ditmari_ Rost. _P. virescens_ is certainly to be preferred. _N. A. F._, 2692.

Canada, New England, New York, Pennsylvania, Ohio, Iowa, Black Hills, South Dakota.

15. PHYSARUM RUBIGINOSUM _Fries_.

1817. _Physarum rubiginosum_ Fries, _Symb. Gast._, p. 21.