- Similar Species
Notice the green staining above.
Russula brevipes is a species of mushroom commonly known as the short-stemmed russula or the stubby brittlegill. It is widespread in North America, and was reported from Pakistan in 2006. The fungus grows in a mycorrhizal association with trees from several genera, including fir, spruce, Douglas-fir, and hemlock. Fruit bodies are white and large, with convex to funnel-shaped caps measuring 7–30 cm (3–12 in) wide set atop a thick stipe up to 8 cm (3 in) long. The gills on the cap underside are closely spaced and sometimes have a faint bluish tint. Spores are roughly spherical, and have a network-like surface dotted with warts.
The mushrooms of Russula brevipes often develop under masses of conifer needles or leaves of broadleaved trees, and fruit from summer to autumn. Forms of the mushroom that develop a bluish band at the top of the stipe are sometimes referred to as variety acrior. Although edible, Russula brevipes mushrooms have a bland or bitter flavor. They become more palatable once parasitized by the ascomycete fungus Hypomyces lactifluorum, a bright orange mold that covers the fruit body and transforms them into lobster mushrooms:
Fully grown, the cap can range from 7 to 30 cm (3 to 12 in) in diameter, whitish to dull-yellow, and is funnel-shaped with a central depression. The gills are narrow and thin, decurrent in attachment, nearly white when young but becoming pale yellow to buff with age, and sometimes forked near the stipe. The stipe is 3–8 cm long and 2.5–4 cm thick. It is initially white but develops yellowish-brownish discolorations with age. The mushroom sometimes develops a pale green band at the top of the stipe. The spore print is white to light cream.
Spores of R. brevipes are egg-shaped to more or less spherical, and measure 7.5–10 by 6.5–8.5 µm; they have a partially reticulate (network-like) surface dotted with warts measuring up to 1 µm high. The cap cuticle is arranged in the form of a cutis (characterized by hyphae that run parallel to the cap surface) comprising interwoven hyphae with rounded tips. There are no cystidia on the cap (pileocystidia).
The variant R. brevipes var. acrior Shaffer has a subtle green shading at the stipe apex and on the gills. R. brevipes var. megaspora has spores measuring 9–14 by 8–12 µm.
It is a common ectomycorrhizal fungus associated with several hosts across temperate forest ecosystems. Typical hosts include trees in the genera Abies, Picea, Pseudotsuga, and Tsuga. The fungus has been reported in Pakistan’s Himalayan moist temperate forests associated with Pinus wallichiana. Fruit bodies grow singly or in groups; fruiting season occurs from summer to autumn. In western North America, where the mushroom is quite common, it is encountered most frequently in late autumn. The mushrooms are usually found as “shrumps”—low, partially emerged mounds on the forest floor, and have often been partially consumed by mammals such as rodents or deer.
Studies have demonstrated that geographically separated R. brevipes populations (globally and continentally) develop significant genetic differentiation, suggesting that gene flow between these populations is small. In contrast, there was little genetic differentiation observed between populations sampled from a smaller area (less than approximately 1000 meters). R. brevipes is one of several Russula species that associates with the myco-heterotrophic orchid Limodorum abortivum.
Russula brevipes is a non-descript edible species that tends to assume the flavors of meats and sauces it is cooked with. It is one of several Russula species harvested in the wild from Mexico’s Izta-Popo Zoquiapan National Park and sold in local markets in nearby Ozumba. The mushrooms are suitable for pickling due to their crisp texture.
Fruit bodies are commonly parasitized by the ascomycete Hypomyces lactifluorum, transforming them into an edible known as a lobster mushroom. In this form, the surface of the fruit body develops into a hard, thin crust dotted with minute pimples, and the gills are reduced to blunt ridges. The flesh of the mushroom—normally brittle and crumbly—becomes compacted and less breakable.
Sesquiterpene lactones are a diverse group of biologically active compounds that are being investigated for their antiinflammatory and antitumor activities. Some of these compounds have been isolated and chemically characterized from Russula brevipes: russulactarorufin, lactarorufin-A, and 24-ethyl-cholesta-7,22E-diene-3β,5α,6β-triol.
The subalpine waxy cap (Hygrophorus subalpinus) is somewhat similar in appearance to R. brevipes but lacks its brittle flesh, and it has a sticky, glutinous cap. The Pacific Northwest species Russula cascadensis also resembles R. brevipes, but has an acrid taste and smaller fruit bodies. Another lookalike, R. vesicatoria, has gills that often fork near the stipe attachment. R. angustispora is quite similar to R. brevipes, but has narrower spores measuring 6.5–8.5 by 4.5–5 µm, and it does not have the pale greenish band that sometimes develops in the latter species. The European look-alike R. delica is widely distributed, although rarer in the northern regions of the continent. Similar to R. brevipes in overall morphology, it has somewhat larger spores (9–12 by 7–8.5 µm) with a surface ornamentation featuring prominent warts interconnected by a zebra-like patterns of ridges. The milk-cap mushroom Lactifluus piperatus can be distinguished from R. brevipes by the production of latex when the mushroom tissue is cut or injured.