The North American Slime-Moulds Part 41

PLATE XX., Figs. 10, 10 _a_, 10 _b_.

1829. _Stemonitis ferruginea_ Ehr., Fries, _Myc._ III., p. 158, Syn. excl.

1899. _Stemonitis axifera_ (Bull.) Macbr., _N. A. S._, p. 120, in part.

1904. _Stemonitis flavogenita_ Jahn, _Abh. Bot. Ver. Brandenb._, XLV, p. 265.

1911. _Stemonitis flavogenita_ Jahn, List., _Mycetozoa, 2nd ed._, p. 149.

Sporangia cylindric, obtuse, closely fasciculate, "cinnamon brown,"

stipitate, 5-7 ; stipe short, black, columella ceasing abruptly below the apex; capillitium a loose net-work with many broad expansions; the peridial net very delicate, the meshes small but uneven, 6-15 , with many projecting points; spores pale ferruginous, verruculose, 7-9 .

This is _S. ferruginea_ Ehr. of Fries with its plasmodium yellow. Fries says "flavicat," _becomes_ yellow, if one may follow the a.n.a.logy of corresponding Latin verbs of color, so that the record of color-changes in the present species is yet to be recorded.

Until further experience may advise to the contrary, we may a.s.sume that all stemonites cinnamon-brown in color, with widened columella-tip, and pale yellowish spores 7-9 in diameter, have at some time in their history a yellow plasmodium, and accordingly represent in America the new-found species.

The larger spores, and, the strange proliferate development of the columella-tip, to which Miss Lister has happily called attention, const.i.tute the essential diagnostic features here.

Our only specimens so far are from Oregon.

14. STEMONITIS PALLIDA _Wingate._

PLATE XIII., Fig. 3

1897. _Stemonitis pallida_ Wing., _N. A. F._, Ell. and Ev., No. 3498.

1899. _Stemonitis pallida_ Wing., Macbr., _N. A. S._, p. 123.

1911. _Stemonitis pallida_ Wing., List., _Mycetozoa, 2nd ed._, p. 149.

Sporangia gregarious, or somewhat cl.u.s.tered, erect, cylindric obtuse, short, blackish brown, rubescent, becoming pallid, stipitate; stipe short, black, polished, rising from a thin, brown, or iridescent hypothallus; columella percurrent, ceasing abruptly at the apex; capillitium filling the interior with abundant branches which form at the surface a close-meshed net, little developed above, making the apex very blunt; spores in ma.s.s, dark brown, by transmitted light dusky, nearly smooth, 7.5 .

This species is well recognized at sight, among the fuscous forms, by its scattered, erect habit. In color it is not unlike _S. fusca_, but has an added reddish tinge. In form it is peculiar by virtue of the blunt rounded apex which seems to be a constant character. The spores under moderate lens are perfectly smooth, under the 1-12 they present very delicate low scattered papillae.

Rare; eastern part of United States.

15. STEMONITIS CAROLINENSIS _Macbr._

PLATE XIII., Fig. 5.

1894. _Stemonitis tenerrima_ Berk. & C., Morg., _Jour. Cin. Soc._, p. 53.

1899. _Stemonitis carolinensis_ Macbr., _nom. nov._, _N. A. S._, p. 152.

1911. _Stemonitis pallida_ Wing., Lister, _Mycetozoa, 2nd ed._, p. 149.

Sporangia tufted in scattered cl.u.s.ters, small, slender, cylindric but tapering from the apex, at first ferruginous then ashen or purplish, stipitate; the stipe short, black and s.h.i.+ning, one-fourth the total height or less, even; hypothallus well developed, black or very dark brown; columella black, gradually diminis.h.i.+ng, at length dissipated some distance below the clavate or ac.u.minate apex of the sporangium; capillitium dense, the inner of many, scarcely expanded, pallid, freely anastomosing branches, the outer a net of very small meshes, often less than the spores, 3-15 , peridial processes imperceptible; spore-ma.s.s pale ferruginous, spores by transmitted light pale violaceous brown, smooth, 6-7 .

Very closely related to the preceding, but recognizable by its proportionately much more slender, taller, ac.u.minate sporangia, paler, and denser capillitium and the remarkably close-meshed net.

Not uncommon south: Kentucky, Alabama.

16. STEMONITIS HERBATICA Pk.

PLATE XVI., Figs. 14, 14 _a_, 14 _b_.

1874. _Stemonitis herbatica_ Peck, _Rep. N. Y. Mus._, XXVI., p. 75.

1899. _Stemonitis axifera_ (Bull.) Macbr., _N. A. S._, p. 120, in part.

1911. _Stemonitis herbatica_ Pk., Lister, _Mycetozoa_, p. 148.

Sporangia cl.u.s.tered, in scattered tufts, cylindric, obtuse, pallid ferruginous, stipitate or sometimes nearly sessile; stipe fuscous or jet-black, only slightly expanded below, much shorter than the columella; hypothallus scanty or none; columella lessening upward, sometimes attaining the apex of the sporangium, sometimes dissolved in capillitial threads some distance below; capillitium of rich brown threads forming the usual inner network of medium density, with many wide expanded nodes, the surface net made up of delicate, almost colorless threads surrounding small polygonal meshes; spore-ma.s.s ferruginous, spores by transmitted light very pale, brownish, minutely warted, 7-9 .

The plasmodium of this species is variously cited from white to yellow.

Probably each report is true, dependent on the relative time of the observation.

The low tufts of brown sporangia with short black stipes, borne often as Dr. Peck found them, a.s.sembled on living leaves, distinguish this little species. In the former edition this form was tentatively enrolled under _S. axifera_ (Bull.); but see further under that species.

Probably widely distributed, but confused with short forms of other species; sometimes also on rotten wood or other substratum; so reported.

New York to Iowa; Was.h.i.+ngton and Oregon. Reported also from Europe.

=3. Comatricha= (_Preuss_) _Rost._

1851. _Comatricha Preuss_, _Linnaea_, XXIV., p. 140.

1873. _Comatricha_ Rostafinski, _Versuch_, p. 7.

Sporangia cylindric or globose, stipitate; stipe prolonged upward to form a more or less extended and tapering columella bearing branches on every side, which by repeated divisions and reunions form the capillitium; ultimate branch-tips free, not supporting a surface net parallel to the peridial wall; peridium evanescent, perhaps sometimes not developed at all.

The genus _Comatricha_ was set off from _Stemonitis_ by the joint effort of Preuss (1851) and Rostafinski (1873-5). Preuss included in his genus, _Comatricha_, alien forms, and besides failed to give an accurate definition; included, however, in his list some species which have since been known by his generic name.

The distinction between the two genera is almost an artificial one, and species are sometimes arbitrarily a.s.signed to one genus or the other.

The diagnosis in any case turns upon the presence or absence of a surface net, formed, in _Stemonitis_, by the anastomosing of the ultimate divisions of the capillitial branches. In _Comatricha_ the anastomosing is general, from the columella out, and is not specialized at the surface.

Recent attempts to reunite the genera here compared seem to result in no apparent advantage. The genera come very near together, but their separation along the line suggested by Rostafinski remains convenient.

=Key to the Species of Comatricha=

_A._ Sporangia closely cl.u.s.tered.

_a._ Obovate or short cylindric.

1. Spores verruculose 1. _C. caespitosa_

2. Spores reticulate 2. _C. cylindrica_

_b._ Elongate, reddish-brown, tufts extended 3. _C. flaccida_

_B._ Sporangia scattered more or less widely.

_a._ Capillitium lax, open.