- 1829. Hemiarcyria Fries, Syst. Myc., III., p. 183 in part.
- 1873. Hemitrichia Rost., Versuch, p. 14.
Capillitium a tangled net of more or less branching and anastomosing fibres centrally attached; the sculpture regular, of conspicuous spirally winding bands or ridges; habit and color various.
The species here associated are intermediate between Arcyria and Trichia, resembling the former in the capillitial net and the latter in thread-sculpture. Fries applied the name Hemiarcyrieae to a group of trichias so-called, citing H. rubiformis as the first. In his Versuch Rostafinski wrote Hemitrichia and afterward Hemiarcyria in the Monograph. Massee combines the genera Arcyria and Hemiarcyria under the former name.
Key to the Species of Hemitrichia
1. Hemitrichia serpula (Scop.) Rost.
[Plate III.], Figs. 4, 4 a, 4 b.
- 1772. Mucor serpula Scop., Fl. Carn, II., p. 493.
- 1794. Trichia serpula (Scop.) Pers., Röm. N. Bot. Mag., I., p. 90
- 1875. Hemiarcyria serpula (Scop.) Rost., Mon., p. 266.
Fructification plasmodiocarpous, often covering several square centimetres, terete, branching freely and usually everywhere reticulate, rusty, tawny, or bright yellow; the peridium thin, transparent, with irregular dehiscence; hypothallus none; capillitium variable, a tangle of long yellow threads, sparingly branched, free everywhere, except below, spinulose, the free tips spinose, acuminate, spiral ridges three or four, with traces of longitudinal striæ; spore-mass golden yellow, spores beneath the lens pale yellow, globose, delicately reticulate, about 10 µ.
Very common, recognized by its bright yellow color and conspicuous reticulate habit. The plasmodium is yellow, at least upon emergence, and passes almost without change to fruit. Found on rotten logs of every description, on the lower surface. In the Mississippi valley, the lower surface of planks used in the construction of sidewalks appears to be a favorite habitat.