Volvopluteus gloiocephalus, commonly known as the big sheath mushroom, rose-gilled grisette, or stubble rosegill, is a species of mushroom in the family Pluteaceae. For most of the 20th century it has been known under the names Volvariella gloiocephala or Volvariella speciosa, but recent molecular studies have placed it as the type species of the genus Volvopluteus, newly created in 2011. The cap of this mushroom is about 5–15 cm (2–6 in) in diameter, varies from white to grey or grey-brown, and is markedly sticky when fresh. The gills start out as white but they soon turn pink. The stipe is white and has a sack-like volva at the base. Microscopical features and DNA sequence data are of great importance for separating V. gloiocephalus from related species. V. gloiocephalus is a saprotrophic fungus that grows on grassy fields and accumulations of organic matter like compost orwoodchips piles. It has been reported from all continents except Antarctica.
The cap of Volvopluteus gloiocephalus is between 5 and 15 cm (2.0 and 5.9 in) in diameter, more or less ovate or conical when young, then expands to convex or flat, sometimes with a slight central depression in old specimens. The surface is markedly viscid in fresh basidiocarps; the color ranges from pure white to grey or greyish-brown. The gills are crowded, free from the stipe,ventricose (swollen in the middle), and up to 2 cm (0.8 in) broad; they are white when young but turn pink with age. The stipe is 8–22.5 cm (3.1–8.9 in) long and 0.7–1.5 cm (0.3–0.6 in) wide, cylindrical, broadening towards the base; the surface is white, smooth or slightly pruinose (covered with fine white powdery granules). The volva is 2–3 cm (0.8–1.2 in) high, sacciform (pouch-like), white and has a smooth surface. The flesh is white on stipe and cap and it does not change when bruised or exposed to air. Smell and taste vary from indistinct to raphanoid (radish-like) or similar to raw peeled potatoes. The spore print is pinkish-brown.
The basidiospores are ellipsoid and measure 12–16 by 8–9.5 µm. Basidia are 20–35 by 7–15 µm and usually four-spored, but sometimes two-spored basidia can occur.Pleurocystidia are 60–90 by 20–50 µm with variable morphology: club-shaped, fusiform, ovoid, and sometimes with a small apical papilla. Cheilocystidia are 55–100 by 15–40 µm with similar morphology to the pleurocystidia; they completely cover the gill edge. The cap cuticle (pileipellis) is an ixocutis (parallel hyphae wide embedded in a gelatinous matrix). Stipitipellis is a cutis (parallel hyphae not embedded in a gelatinous matrix). Caulocystidia are sometimes present, measuring 70–180 by 10–25 µm; they are mostly cylindrical. Clamp connections are absent from the hyphae.
Volvopluteus gloiocephalus is edible, although it is cited as mediocre or of poor quality. It was once sold in markets in Perth, Australia. Mature fruit bodies, collected in sufficient quantity, can be used to prepare soup, or added to dishes where wild mushrooms are used, such as stews and casseroles. The mushrooms are best used fresh as they do not preserve well. Young specimens of Volvopluteus gloiocephalus have white gills so it is possible to mistake them for an Amanita and vice versa. In the United States, there have been several cases of Asian immigrants collecting and eating death caps (Amanita phalloides), under the mistaken assumption that they were Volvariella. A Greek study determined the nutritional composition of fruit bodies: protein 1.49 g/100 g fresh weight (fw), 18.36 g/100 g dry weight (dw); fat 0.54 g/100 g fw, 6.65 g/100g dw;carbohydrates 5.33 g/100g fw, 65.64 g/100 g dw..From Wikipedia, the free encyclopedia
Photos Akanthou 5/12/2012 by George Konstantinou
