Sporangia gregarious, clustered but distinct, sessile small, about .75 mm., bright yellow, peridium double. The outer rough, breaking up into comparatively few rather large deciduous scales, the inner peridium white, calcareous, both persisting below to form a distinct cup; capillitium lax, the nodes white, large, angular; columella none; hypothallus none; spores distinctly rough, dark brown with the usual purple shadow, 10–12 µ.
A very distinct little species related, no doubt, to P. contextum, but different in habit. It is never crowded, shows no plasmodiocarpous tendencies, while the outer peridium is generally deciduous except at the base and falls in flakes.
Collected several times in the Three Sisters Mountains of Oregon by Professor Morton E. Peck.
12. Physarum brunneolum (Phillips) Mass.
[Plate XX]., Figs. 7, 7 a.
- 1877. Diderma brunneolum Phillips, Grev., V., p. 114.
- 1888. Diderma brunneolum Phill., Saccardo, Syll. Fung., No. 1292.
- 1892. Physarum brunneolum Phill., Massee, Mon., p. 280, Figs. 221–222.
- 1894. Craterium pedunculatum Lister, Mycetozoa, p. 71.
- 1911. Physarum brunneolum Mass., Lister, Mycetozoa, 2nd ed., p. 63, Pl. 69, Fig. a.
Sporangia scattered or gregarious, but not crowded, sessile, globose or sub-depressed; peridium double, thick, smooth or polished, yellow brown, stellately dehiscent, the segments reflexed, white within; columella none; capillitium dense, with nodes numerous, large irregular, internodes thin and short; spores globose, lilac, minutely warted, 6–7 µ.
This form was first described in Grevillea, V., p. 114, as Diderma brunneolum Phillips. Later, students of the specimens preserved by Mr. Phillips, concur that we have to do not with a diderma, but with a craterium, Lister, or physarum, Massee. There seems no reason why we should not respect the decision of Massee, whose description is here quoted in form somewhat abridged. The peridium is about as double as in the many physarums, not more so; the inner membrane so delicate as only occasionally to be revealed except to scrutiny most searching. But the appearance as a whole is as of some brown diderma; only the calcareous capillitium abides to prevent mistaken reference.
When opened by irregular dehiscence from above, the persisting cup-like base of the sporangium recalls Leocarpus fragilis; but then again the capillitium is different.
California, Portugal; Colorado,—Sturgis.