[Plate XVI.], Figs. 11, 11 a, 11 b.
- 1879. Didymium eximium Peck, Rep. N. Y. Mus., XXXI., p. 41.
Sporangia scattered, dull grayish-yellow or gray, depressed-globose, umbilicate, minute, stipitate; the peridium comparatively thick, tenacious, especially persistent below, tawny or yellow; the stipe pale brown or orange, erect, even or slightly enlarged at base; hypothallus scant or none; columella prominent, more or less discoidal, rough, or spinulose, especially on the upper surface, yellow; capillitium not abundant, pale fuliginous, often branching and anastomosing so as to form a loose net; spores nearly smooth, dark violaceous by transmitted light, 8.5–9.5 µ.
The species differs from D. xanthopus in several particulars,—in the much firmer, more persistent, and less calcareous peridium, in the more complex capillitium, in the darker and larger spores, and especially in the peculiar and prominent columella, which is not only rough, but even "sometimes spinulose even to the extent of long spicules penetrating to one-third the height of the sporangia." N. A. F., 2493.
As stated under No. 8, these last two species are called varieties only of D. nigripes. They are so retained in Mycetozoa, 2nd ed. Since, however, they are the usual presentation of the species in the United States, it seems wise to let them stand for the present, as here. They are quite distinguishable; D. eximium especially well marked.
Apparently rare, it yet ranges from New York to eastern Iowa, in colonies rather large. Okoboji Lake;—fine!
13. Didymium trochus List.
- 1898. Didymium trochus List., Jour. Bot., XXXVI., p. 164.
Sporangia plasmodiocarpous, hemispherical or turbinate, white, sessile or very short-stalked, cream-colored or white; peridium double, the outer shell-like, the inner membranaceous, more or less adherent to the outer, both caducous together, leaving the thickened base surrounding an expanded columella; stipe, when present, very short, stout; capillitium colorless, nearly simple; spores brownish-purple, strongly warted, 9–10 µ.
On decaying leaves, rotten cactus, yucca, etc., Monrovia, California; Bethel.