Volvariella bombycina

Description

This rare and striking silky-capped edible mushroom. Often emerges from knot holes and other damaged areas high up on standing trees. It is not parasitic, and even when seen on living trees it is invariably attached to deadwood.

It is an uncommon but widespread species, having been reported from Asia, Australia, the Caribbean, Europe, and North America. The fruit body (mushroom) begins developing in a thin, egg-like sac.

Inexperienced mushroom gatherers should avoid gathering any fungi that have volvas (although in Britain and Ireland the risk is minimized by the fact that there are no Amanita species recorded as growing, as the Silky Rosegill does, on wood rather than on soil).

Common names: Silky Sheath, Silky Rosegill, Silver-Silk Straw Mushroom, Tree Mushroom.

Mushroom Identification

1. Ecology

   Saprobic on the wood of various hardwoods, either on dead trees or from the wounds of living, standing trees in forests or urban areas; usually growing alone but sometimes growing gregariously; late spring, summer and fall; widely distributed in North America but much more common east of the Rocky Mountains (and in western areas usually appearing in urban settings on the wood of cultivated trees); also found Central America, the Caribbean, South America, Europe, and central Asia—and occasionally reported from Africa and Oceania.

2. Cap

   5–12 cm; oval to subconic at first, becoming bell-shaped to broadly convex or nearly flat; dry; covered with silky hairs; snow-white when young and fresh, but the hairs often becoming yellowish to brownish in age, especially over the center; the margin not becoming lined.

3. Gills

   Free from the stem; crowded; white at first, becoming pink.

4. Stem

   6–15 cm long; 1–2.5 cm thick; more or less equal, but usually tapering somewhat to apex; often curved to set the cap "straight" due to growth on standing trees; dry; fairly bald; white; without a ring; the base encased in a thick, white to yellowish or brown, sack-like volva.

5. Flesh

   White; unchanging when sliced.

6. Spore Print

   Brownish pink.

Medicinal Properties

Antioxidant activity

Both the culture liquid and the mycelial biomass of V. bombycina were shown to have good antioxidative activity, as measured by the ability to inhibit the free radical peroxidation of lipids in rat brain homogenate (Badalyan et al., 2003). Further study into various factors contributing to the antioxidant levels in this species have also been reported (Badalyan and Suzanna, 2003).

Antitumor activity

Polysaccharides extracted from the mycelial culture of V. bombycina and administered intraperitoneally into white mice at a dosage of 300 mg/kg inhibited the growth of Sarcoma 180 and Ehrlich solid cancers by 100% (Ohtsuka et al., 1973).

History

When in 1762 Jacob Christian Schaeffer described this mushroom he gave it the scientific name Agaricus bombycinus. (Most gilled fungi were initially placed in a giant Agaricus genus, now redistributed to many other genera.) It was German-born mycologist Rolf Singer who, in 1949, transferred this species to the genus Volvariella, at which point its binomial scientific name became Volvariella bombycina.

Synonyms of Volvariella bombycina include Agaricus bombycinus Schaeff., and Volvaria bombycina (Schaeff.) P. Kumm.

Volvariella, the genus name, is a reference to the volva formed around the stem base by the remnants of the membranous universal veil which covers emerging fruitbodies. The specific epithet bombycina comes from the Latin bombycis and means silky.

Photo sources:

Photo 1 - Author: Lukas from London, England (CC BY-SA 2.0)

Photo 2 - Author: Hagen Graebner (CC BY-SA 3.0)

Photo 3 - Author: reginahart [Regina (Gina) Hart] (CC BY-SA 4.0)

Photo 4 - Author: Dave in NE PA (CC BY-SA 3.0)