The North American Slime-Moulds Part 43

5. COMATRICHA IRREGULARIS _Rex._

1891. _Comatricha irregularis_ Rex, _Proc. Phil. Acad._, p. 393.

Sporangia crowded in flocculent tufts, very dark brown or black, semi-erect or drooping, 4-5 mm. in height, irregularly cylindric, variable, stipitate; stipe black, distinct, often one-half the total height; hypothallus well developed, brown, shining; columella central, slender, flexuous, reaching the apex, where it blends, by branching, with the capillitium; capillitium loose, open, composed of arcuate threads which radiate from the columella, and are joined together, forming a central, irregular reticulation of large meshes, brown, paler toward the surface, where the free ends are sometimes colorless; spore-ma.s.s black, spores by transmitted light brown, minutely warted, 7-8 .

Related, no doubt, to _C. longa_, but differing in habit, stature, as in texture and structure of the capillitium. In _C. longa_ the inner net is extremely simple,--a row or two of meshes at most, and the radiating branches are long and straight; in the species before us the inner network is well developed, and the radiating branches proportionately shorter and abundantly branching, with pale or white free tips.

Generally, though not always, found growing in the crevices of the bark on fallen logs of various deciduous trees. September. Not common.

This is thought to be _C. crypta_ Schw., _N. A. F._, 2351; but the description under that number does not make clear what form Schweinitz had before him, the present species or _C. longa_, and the herbarium specimen of Schweinitz is "utterly lost"; the later specific name is accordingly adopted.

New England west to the Cascade Mountains; south to Kansas and Texas.

6. COMATRICHA LAXA _Rostafinski._

PLATE V., Figs. 5, 5 _a_.

1875. _Comatricha laxa_ Rost., _Mon._, p. 201.

1877. _Lamproderma ellisiana_ Cooke, _Myx. U. S._, p. 397.

1891. _Comatricha ellisiana_ (Cooke) Ell. & Ev., _N. A. F._, 2696.

Sporangia scattered, gregarious, sub-globose or short cylindric, and obtuse, dusky stipitate; stipe short, black, tapering rapidly upward from an expanded base; hypothallus scant or none; columella erect, rigid, sometimes reaching nearly to the apex of the sporangium, sometimes dichotomously branched a little below the summit, before blending into the common capillitium; capillitium lax, of slender, horizontal branches, anastomosing at infrequent intervals and ending in short, free tips; spores pallid, nearly smooth, 7-9.5 .

A very minute, delicate little species, about 1 mm. high; the stipe half the total height. In general appearance the shorter forms of the species resemble slightly _C. nigra_, but are distinguished by a much shorter stipe and much more open capillitium. The sporangia of _C.

nigra_ mounted on long capillary stipes always droops more or less; the sporangia of the present species stand rigidly erect. The sporangia vary in form and in the branching of the columella. In the more globose phases, the columella almost always shows a peculiar dichotomy near the apex; in the cylindric types, this peculiar division fails.[36] In fact, the shape is determined chiefly by the mode of branching as affects the columella. Rostafinski's figure, on Tab. XIII, does not present the type usually seen in this country, nor even in Europe if we may judge from later ill.u.s.trations.

The species with us has received various names, but so far as can be determined, all apply to the same thing, and comparison of specimens from Mr. Ellis with those from Europe show the correctness of the nomenclature here adopted.

Rare, but widely distributed; across the continent.

7. STEMONITIS SUKSDORFII _Ell. & Everh._

PLATE XI., Figs. 9, 10, 11.

1882. _Stemonitis suksdorfii_ Ell. & Everh., _Bull. Washb. Coll._, Vol. I., p. 5.

1892. _Stemonitis suksdorfii_ Ell. & Everh., Ma.s.s., _Mon._, p. 76.

Sporangia scattered in small tufts or gregarious, cylindric, obtuse at both ends, sometimes widened above, black, 2-6 mm., stipitate; stipe jet-black, shining, even, about one-half the total height; hypothallus not continuous, dark brown; columella black, rather slender, terminating in two or more large branches just below the apex; capillitium exceedingly dense, dark fuscous or black, the flexuous threads anastomosing in a close network, with abundant free pallid extremities; spores in ma.s.s, blue-black, by transmitted light fuscous or dark violaceous-brown, minutely warted, 10-12 .

Easily recognizable at sight by its sooty color. Entirely unlike any of the preceding. The type of the capillitium is that of _C. pulch.e.l.la_, but it is very much more dense and entirely different in color. The sporangia are often widened above, and fairly truncate; the total height about 6 mm. Found on the bark of fallen twigs of _Abies, Larix_, etc.

Distributed by Ell. & Everh. under this name as an _exsiccata_. The evanescent peridium is colorless; when free, white or silvery.

8. COMATRICHA NIGRA (_Pers._) _Schroeter._

PLATE XI., Figs. 1, 2, 3.

1791. _Stemonitis nigra_ Pers., Gmel., _Syst. Nat._, p. 1467.

1801. _Stemonitis ovata_, var. _nigra_ Pers., _Syn._, p. 189.

1863. _Stemonitis friesiana_ DeBy., _Rab. Eur. Fung._, No. 568.

1875. _Comatricha friesiana_ (DeBy.) Rost., _Mon._, p. 200.

1889. _Comatricha nigra_ (Pers.) Schroeter, _Pilz. Krypt. Fl.

v. Schles._, I., p. 118.

1894. _Comatricha obtusata_ Fr., Lister, _Mycetozoa_, p. 117.

1899. _Comatricha nigra_ (Pers.) Schroeter, Macbr., _N. A. S._, p. 128.

Sporangia scattered, ferruginous or dark brown, globose or ovoid, stipitate; stipe long, hair-like, tapering upward, black; hypothallus none; columella rapidly diminished toward the top, at length dissipated; capillitium of slender flexuous threads, radiating horizontally, repeatedly branching and anastomosing to form an intricate dense network, from the surface of which project a few short hook-like peridial processes; spore-ma.s.s black, spores by transmitted light dark violaceous, smooth or nearly so, 7-10 .

This species, when typical, is easily recognized by its almost globose sporangia mounted on long slender stocks. These are 2 or 3 mm. high and generally persist, as Persoon noticed, a long time after the sporangium has fallen. The sporangia are at first black; after spore disposal pale ferruginous. In shape they vary from ovate to spherical. Sometimes they are umbilicate below, so that a vertical section would be obcordate.

Care must be taken to distinguish the present species from blown-out forms of _Lamproderma_.

This most common species seems to be also the center of widest differentiation. In a valuable paper on the Myxomycetes of Dr. C. H.

Peck's Herbarium Dr. Sturgis points out the varying relationships of a group of surrounding forms. According to account _C. nigra_ verges on one side to _C. laxa_, on the other to _aequalis_ which the Listers enter as varietal here. However, in the former the more rigid, direct and simple branching from the columella is usually determinative; in the latter the color, form, and generally more delicate structure, and a tendency to grow in tufts will serve to distinguish.

In this discussion we have a.s.sumed as typical the globose sporangium, with the variations in the direction of ovate, obovate, ellipsoidal, etc., the capillitium flexuous and more richly anastomosing near the columella. On the drier slopes in the mountains of Colorado specimens are especially abundant, in proper season covering apparently the lower surface of every barkless twig or fallen stem or _tree entire_! In such a field one might imagine every possible variation open to observation.

Probably such is the case; but as a matter of fact a single small plasmodium at lower levels will sometimes show greater range of variation than were noted on the mountain-side. The cylindric forms were for some reason few, and when noted were short, though often surmounting stems of double the usual length.

Rostafinski calls this _C. friesiana_, a name suggested by De Bary. By this name the species was commonly known for many years. More recently some writers prefer _C. obtusata_ Preuss; but _C. obtusata_ Preuss, as figured by that author (Sturm's _Deutsch. Fl._, Pl. 70), is surely more likely _Enerthenema papillata_, and the author says in his description "capillitio vertice soli innato." Persoon certainly recognized the species, and his description, though brief, is yet applicable to no other European species. There seems no reason why the name he gave should not be permanently adopted. Rostafinski's figure, Tab. XIII., shows an ellipsoidal sporangium, not cylindric.

On the lower levels of the Mississippi valley, the species is not common. Possibly overlooked by reason of its minuteness.

Ma.s.sachusetts, Pennsylvania, Ohio, Iowa, Colorado, North Carolina, Missouri.

9. COMATRICHA aeQUALIS _Peck._

PLATE VI., Figs. 3, 3 _a_, 3 _b_, 3 _c_, 3 _d_; and PLATE XVIII., Figs.

13, 13 _a_, 13 _b_.

1890. _Comatricha equalis_ Peck., _Rep. N. Y. Mus._, x.x.xI., p. 42.

Sporangia gregarious, seldom erect, usually inclined, curved or nodding, dark brown, becoming violet, cylindric, ac.u.minate-obtuse, stipitate; stipe about half the total height, 2-2 mm., black, polished, even; hypothallus well developed, brown, continuous; columella black, tapering gradually, and attaining almost the summit of the sporangium; capillitium dense, of flexuous tawny threads which, by repeated branching, form an intricate network, the free extremities numerous, short, and pale; spores dark violaceous, distinctly warted, 7.5-8 .

A very graceful, elegant species, related to _C. pulch.e.l.la_ and _C.

persoonii_, but distinct by its much greater size and smaller spores.

The specimens before show us the perfection of beauty in this genus; the polished stipe, the symmetrical capillitium, the soft purple-brown tints, are remarkable, and enable one to recognize the form at sight.

Specimens from Oregon are unusually fine; larger than usual, reach 7 mm.

total height, and when blown out present the tints of violet in unusual clearness; var. _C. pacifica_. Plate XVIII., Figs. 13, 13_a_, and 13_b_.

New York, Pennsylvania, Ohio, Illinois; Oregon, _Professor Peck._

10. COMATRICHA TYPHOIDES (_Bull._) _Rost._