Photo: © Steve Trudell
Russula aeruginea

Pileus: 3 - 11 cm broad; convex when young, becoming planar finally broadly depressed when mature; margins inrolled at first, then incurved and finally straight and even, at times faintly to prominently striate, surface smooth, at times with minute bumps, in dry weather dry but usually moist to viscid, peels variously, from not at all to just before disc; colours variable with shades of greens and yellows, olive to greyish to brownish green to deep green, to greyish yellow, colours even, or becoming paler towards margins; context 5 mm at junction of stipe, firm to brittle, white, unchanging when bruised; taste mild; odour indistinct to described as ‘yeast-like’.

Lamellae: Ascending when young, becoming horizontal then notched, and at times decurrent, spaced average to crowded at times distant; edges even, forking towards stipe; colour white when young, becoming yellowish white to yellow when mature, at times bruising brown; no lamellulae.

Stipe: 4 - 9.0 cm long X 1.5 - 3.5 cm wide, even but occasionally tapering upwards, surface dry, unpolished, colour white, often becoming yellow when handled, at times with tint of pink at apex; context white, unchanging, spongy, solid.

Microcharacteristics: Spore print yellow; spores globose to subglobose, 8.9 - 10.4 X 7.4 - 8.9 µm, with amyloid warts; abundant hymenial cystidia.

Comments: This species is very common in these forests and is distinctive by having yellow to deep green colours. It is similar to R. occidentalis, but unlike that species, R. aeruginea doesn’t bruise red then grey black when injured.

Further Reading:

Arora, D. 1986. Mushrooms Demystified. Ten Speed Press. Berkeley, Ca. pp 958.

Thiers, H.D. 1997. The Agaricales (gilled fungi) of California. 10. Russulaceae I. Russula. Mad River Press. Eureka Ca. pp 158.