The North American Slime-Moulds Part 35

1825. _Leangium trevelyani_ Grev., _Scot., Cr. Fl._, Tab. 132.

1829. _Diderma trevelyani_ (Grev.) Fr., _Syst. Myc._, III., p. 105.

1875. _Chondrioderma trevelyani_ (Grev.) Rost., _Mon._, p. 182.

1877. _Diderma geasteroides_ Phill., _Grev._, V., p. 113.

1877. _Diderma laciniatum_ Phill., _Grev._, V., p. 113.

Sporangia scattered, globose or nearly so, smooth or verruculose, reddish-brown or rufescent, sessile or short-stipitate, the outer peridium firm, splitting more or less regularly into unequal, revolute, petal-like lobes which are white within, the inner not distinguishable as such; stipe, when present, equal, furrowed, concolorous; columella small or none; capillitium abundant, the threads rather rigid, purple or purplish brown, branching and anastomosing, more or less beaded; spores dark, violaceous brown, spinulose, 10-13 .

In 1876, Harkness and Moore collected in the Sierra Nevada Mountains of California, forms of _Diderma_ which are described by Phillips, _Grev._, V., p. 113, as _D. geasteroides_ and _D. laciniatum_. English authorities who have examined the material agree that the forms described const.i.tute but a single species, and Lister makes them identical with _D. trevelyani_ (Grev.) Fr. Rostafinski's figures, 161, 162, are a curious reproduction, evidently, of Fried. Nees von Esenbeck's, Plate IX., Fig. 4. Ma.s.see describes a columella; Lister says there is none. What may occasion such divergence of statement none may say; such forms as come in so far from our western mountains have no columella.

17. DIDERMA ASTEROIDES _List._

PLATE XVIII., Figs. 3, 3 _a_

1902. _Diderma asteroides_ List., _Jour. Bot._, XL, p. 209.

1911. _Diderma asteroides_ List., _Mycetozoa, 2nd ed._, p. 113.

Sporangia globose or ovoid-globose, the apex more or less ac.u.minate, sessile, sometimes narrowed at the base to a short, thick stalk, brown or chocolate tinted, marked at the apex by radiant lines, and at length dehiscent by many reflexing lobes revealing the snow-white adherent inner peridium on the exposed or upper side; columella also white, globose or depressed-globose; capillitium generally colorless, somewhat branched, especially above; spores dark violaceous, verruculose, 10-12 .

Oregon, the Three Sisters Mountains; Colorado; California.

A very beautiful species, recognizable at sight; when unopened, by the peculiar chocolate brown, the sporangia smaller than in _D. radiatum_.

When opened, the snow-white flower-like figure, flat against the substratum, is definitive. Very near number 16 preceding; the dehiscence more regular.

18. DIDERMA FLORIFORME (_Bull._) _Pers._

PLATE VIII., Figs. 1, 1 _a_, 1 _b_.

1791. _Sphaerocarpus floriformis_ Bulliard, _Champ._, p. 142, t. 371.

1794. _Diderma floriforme_ (Bull.) Persoon, _Rom. N. Mag. Bot._, p. 89.

Sporangia crowded, generally in dense colonies, globose, smooth, ochraceous-white, stipitate, the peridium thick, cartilaginous, splitting from above into several petal-like lobes, which become speedily reflexed exposing the swarthy spore-ma.s.s, the inner peridium not discoverable, inseparable; stipe concolorous, about equal to the sporangium; hypothallus, generally well developed, but thin, membranaceous, common to all the sporangia; columella prominent, globose or cylindric, often constricted below, and prolonged upward almost to the top of the spore-case; capillitium of slender, delicate, sparingly branched threads; spores dark violaceous-brown, studded with scattered warts, 10-11 .

Not uncommon, especially on rotten oak logs. Easily recognized by the peculiar form of the fruit, spherical before dehiscence, floriform after. Unlike most species, this form often fruits in dark places, in the interior of a log, even in the ground.

New England, Ontario to Iowa and Nebraska, and south.

19. DIDERMA RUGOSUM (_Rex_) _Macbr._

PLATE XVIII., Fig. 10.

1893. _Chondrioderma rugosum_ Rex, _Proc. Phil. Acad._, p. 369.

Sporangia gregarious, scattered, white or ashen, rugulose over the whole surface, the ridges marking the lines of subsequent rupture or dehiscence, the peridium thin papyraceous, stipitate; stipe well developed about equal to the sporangium, subulate, almost black; hypothallus none; columella distinct, generally white, sometimes small, globose, sometimes penetrating the sporangium, to one-half the height; capillitium white or colorless, the filaments freely forked and combined by lateral branches into a loose network attached to the columella and basal wall below and the upper sporangial wall above; spores violaceous-brown, warted, 8-10 .

This species is well designated _rugosum_, and is recognizable at sight by its wrinkled, areolate surface. Related to _D. radiatum_ in the prefigured dehiscence, but otherwise very distinct. Liable to be overlooked as a prematurely dried physarum. Rare. Plasmodium gray.

North Carolina, Iowa.

=4. Lepidoderma= _DeBary_

1858. _Lepidoderma_ DeBy., MS. Rost., _Versuch_, p. 13.

Sporangia stalked or sessile; peridium cartilaginous, adorned without with large calcareous scales, superficial or shut in lenticular cavities; capillitium non-calcareous.[33]

=Key to Species of Lepidoderma=

_A._ Sporangia stipitate, stipe brown 1. _L. tigrinum_

_B._ Sporangia sessile, plasmodiocarpous, spores 10-12 2. _L. carestianum_

_C._ Sporangia plasmodiocarpous, spores 8-10 3. _L. chailletii_

1. LEPIDODERMA TIGRINUM (_Schrad._) _Rost._

PLATE XIV., Fig. 7.

1797. _Didymium tigrinum_ Schrad., _Nov. Gen. Plantarum_, p. 22.

1873. _Lepidoderma tigrinum_ (Schrad.) Rost., _Versuch_, p. 13.

Sporangia scattered, rather large, hemispherical-depressed, stipitate, umbilicate beneath, the peridium shining, olivaceous or purplish, tough, covered more or less abundantly with angular scales; the stipe stout, furrowed, dark brown, but containing calcareous deposits withal, tapering upward, and continued within the peridium as a p.r.o.nounced more or less calcareous columella; hypothallus more or less prominent, yellowish or brownish; capillitium dark, purplish-brown, of sparingly branching threads radiating from the columella; spores dull purplish-brown, minutely roughened, 10-12 .

A singular species, rare, but easily recognized by its peculiar, placoid scales, large and firmly embedded in the peridial wall. The internal structure is essentially that of _Diderma_ or _Didymium_. The species occurs in hilly or mountainous regions, on moss-covered logs. The plasmodium pale yellow, some part of it not infrequently remains as a venulose hypothallus connecting such sporangia as are near together.

New England to Washington and Oregon; Vancouver Island.

2. LEPIDODERMA CARESTIANUM (_Rabenh._) _Rost._

1862. _Reticularia carestiana_ Rabenh., _MS. Fung. Eur. exsic._, No. 436.

1875. _Lepidoderma carestianum_ (Rabenh.) Rost., _Mon._, p. 188.

1891. _Amaurochaete minor_ Sacc. & Ell., _Mich._, II., p. 566.

Fructification in the form of flat, pulvinate plasmodiocarps, or, anon, sporangiate, the sporangia sessile, sub-globose, ellipsoidal, elongate, irregular, confluent, yellowish-grey, the peridium covered more or less completely with dull white, crystals or crystal-like scales; columella, where visible, yellowish-brown, calcareous; capillitium, coa.r.s.e, rigid, more or less branched and united, or colorless, delicate, forming a definite net; spores distinctly warted, purple 10-12 .

This is a most remarkable species. The sporangiate forms little resemble those distinctly plasmodiocarpal. In the former the calcic scales and crystals are distinct and quite as in _L. tigrinum_; in the latter they are cuboid, irregular. The wall of the peridium in the plasmodiocarps at hand is black, and the covering accordingly shows white; in the sporangial forms the wall is brown, and the scales have a yellow tinge as if tinged with iron. In the sporangial presentation the capillitium is intricate delicate; in the plasmodiocarp, rigid, dark-colored, etc.

This looks like a didymium and in so far justifies the opinion of earlier students. Fries, of course, includes all these things with the didymiums, and _D. squamulosum_ probably often sheltered them under extended wing.

_Didymium granuliferum_ Phill., _Grev._, V., p. 114, from California is by European authors referred here. The capillitium carries calcareous crystalline deposits in special vesicles and the spores show remarkable variation in unusual size--15-30 .[1]

Should probably be entered _Lepidoderma granuliferum_ (Phill.) Fr., spores 15-18 .[34]

Utah,--Harkness.