2. Lamproderma robustum Ell. & Evh.

Sporangia gregarious, globose, dull black, the peridium when present silvery, shining, or simply smooth, transparent and without iridescence, stipitate; stipe short, black, tapering rapidly upward, annulate with the persisting base of the peridium; columella short, thick, truncate, and widened at the top; hypothallus well developed, brown or purple; capillitium dense, made up of dark brown branches, numerous and rather slender, repeatedly branched and anastomosing toward the surface to form a slight delicate network with abundant free ends; spores dark purple brown, rough, 14–16 µ.

This species in outward appearance resembles L. physaroides, from which it is easily distinguished by the much greater diameter of the globose sporangium, 1 mm. or more. The persistent base of the peridium is also characteristic, very prominent sometimes, and visible to the naked eye. The capillitium is also unlike that of L. physaroides; resembles more nearly that of L. violaceum. From the latter species L. robustum is distinguished by the color of the peridium, and by the larger, darker spores and generally different capillitium. In our former edition this is called L. sauteri Rost. That much-quoted author distinguished L. violaceum and L. sauteri; the English authors make the last named a variety only of the former. This our American species is not.

It is, as presented in our western mountains, clear-cut, well defined, not a variety of anything. The original name is therefore restored.

Lamproderma arcyrioides (Somm.) Morgan is probably a form of L. columbinum. The original L. arcyrioides has not yet been certainly identified in North America; see following species.

Colorado, Oregon, Washington, California.

3. Lamproderma columbinum (Pers.) Rost.

Sporangia scattered, gregarious; rich violet or purple with metallic iridescence, globose, stipitate; the stipe long, three-fourths the total height, slender, subulate, black; hypothallus scant, purplish or brown; columella small, one-third the height or less, tapering or acute, black; the capillitium brown throughout, not dense, arising from nearly all parts of the columella, freely branching and anastomosing to an open, large-meshed network; spore-mass black, spores by transmitted light dark brown, rough, 10–12 µ.