Russulales News / Russula mutabilis

Nomenclature

Russula mutabilis Murrill (basionym)
Bull. Torrey bot. Club 67: 146. 1940.

Original diagnosis

Pileus convex to depressed, gregarious, about 5 cm. broad; surface distinctly viscid, smooth, glabrous, orange-brown, changing to dull-red within an hour after picking, purplish-black when dried; margin more or less striate, not peeling readily; context opaque, juicy, odor slightly like that of R. foetens when fresh, like varnish while drying, taste pungent, slightly astringent; lamellae adnate, rather broad, medium distant, forked at the base, entire, pallid or yellowish, reddish when dry; spores subglobose, densely and decidedly spinulose, hyaline under a microscope, 7-8 x 6 u; cystidia none; stipe tapering downward, smooth, glabrous, white, testaceous at the base, soon becoming blood-red below, purplish-red when dried, 4 x 1-1.3 cm.
Type collected by West and Murrill on low ground under hardwood trees in Prairie Creek Hammock, southeast of Gainesville, Fla., July 27, 1938 (F 17943). When I first saw this plant I thought it was R. foetens and started to throw the specimens away, but a red tint on the cap restrained me. When I got to the herbarium the stems were as red as blood on the lower half, with no black. The caps also had deepened to dull-red and later became purplish-black. A determined effort to assign it to Beardslee's R. rubescens met with no success.

Typification

Holotypus: 17943 (F)
North America: United States: Florida: Prairie Creek Hammock, southeast of Gainesville
On low ground under hardwood trees

Published type studies: Hesler (1960).

Description

Photographs

Microscopy

SEM photos