Silky Piggyback

The cap is initially round to convex before flattening, reaching a diameter of 8–20 mm (0.3–0.8 in). The caps of young fruit bodies have a smooth surface that is covered with smooth fibrils. The cap color is white to pale grey, changing to grayish brown in maturity. The cap margin is initially rolled inward. The flesh is thin, with a whitish to brownish color; it has an unpleasant odor and a farinaceous (mealy) taste. The thick, widely spaced gills have an attached to somewhat decurrent attachment to the stem. They are whitish to grayish brown, often poorly developed, sometimes forked near the cap margin, and have edges covered with fine granules. The stipe measures 1–3 cm (0.4–1.2 in) long by 2–3 mm (0.08–0.12 in) thick. Its surface has fine white fibers on a grayish brown background. The base of the cap sometimes is finely velvety and white. Initially solid, the stipe becomes hollow in age. Asterophora parasitica produces a white spore print. The edibility of the mushrooms is unknown. Spores are elliptical, smooth, hyaline (translucent), and measure 5–6 by 3–4 μm. Chlamydospores produced by the gills are spindle-shaped to oval, usually thick-walled, and measure 12–17 by 9–10 μm.

Fruit bodies grow in groups or clusters on the decomposing mushrooms of Lactarius and Russula species, particularly those in the Russula nigricans group. It has been reported from Europe and North America. Although not uncommon in southern and central Europe, it is rare in Scandinavia, where it does not grow outside the northern limit of Quercus (oak) species, suggesting that character of the soil in which the host mushrooms grow can affect the suitability as a substrate for A. parasitica. It takes about three weeks for A. parasitica to complete its development on an agaric. The yeast Asterotremella albida has been isolated from the gill tissue of Asterophora parasitica. The yeast, which is also found on Asterophora lycoperdoides, is tremelloid, meaning it has cup-shaped parenthesomes.

Much of the life cycle of Asterophora parasitica was first elaborated in detail by German mycologist Julius Oscar Brefeld, who was able to germinate basidiospores and chlamydospores.