Russula brevipes
Description
Russula brevipes is one of the most common Russula species on the west coast and is easily identified by its stature, large size, and white coloration which does not stain when handled. Grow solitary to scattered to gregarious in the soil of our coastal forests, often in great abundance; most common late fall.
It is edible, although its quality is improved once parasitized by the ascomycete fungus Hypomyces lactifluorum, transforming it into an edible known as a lobster mushroom.
Common names: Short-stemmed Russula, Stubby Brittlegill.
Mushroom Identification
Ecology
Mycorrhizal with a wide variety of trees, from conifers to hardwoods. Growing alone, scattered, or gregariously; common; summer and fall, or overwinter in warm climates; fairly widely distributed in North America, at least as a species group.
Cap
6–20 cm; convex with a central depression and an inrolled margin when young, later broadly convex with a central depression and eventually shallowly vase-shaped, the margin remaining somewhat inrolled or straightening; dry; bald or suedelike; sometimes becoming cracked in age; white to whitish or creamy at first, developing brownish discolorations and sometimes becoming brownish to orangish brown overall with old age; the margin not lined; the skin fairly tightly adnate, not peeling easily.
Gills
Attached to the stem or running down it slightly; crowded or close; short-gills frequent; white at first, becoming creamy; sometimes spotting and discoloring brownish; sometimes bluish to blue, especially near the juncture with the stem.
Stem
3–4 cm long; 1.5–3 cm thick; sturdy and solid; more or less equal; dry; bald; whitish; usually discoloring and bruising brown to brownish; basal mycelium white.
Flesh
White; sometimes discoloring brownish when sliced.
Odor and Taste
Odor not distinctive, faintly foul, or faintly fragrant; taste mild to slightly, moderately, or strongly acrid.
Chemical Reactions
KOH negative to faintly yellowish on cap surface. Iron salts negative on stem surface.
Spore Print
White to creamy.
Microscopic Features
Spores 7–10 x 5–7 µm (but in some collections much smaller: 4–7 x 4–5 µm); broadly ellipsoid to subglobose; ornamentation usually about 0.5 µm high, as amyloid warts and occasional connectors that may be fairly isolated, or may form subreticulate patterns. Pleuro- and cheilocystidia 35–50 x 7.5–10 µm; fusiform, cylindric, or subclavate, sometimes with one or more apical constrictions or knobs; thin-walled; hyaline. Pileipellis is a cutis of hyaline to yellowish elements 2.5–5 µm wide. Oleiferous hyphae present.
Look-Alikes
Russula cascadensis
Is easily confused with the short-stalked russula. The taste of gills (take a pea-sized bite, taste for a few moments, spit out) of the cascade russula, R. cascadensis ranges from very hot to acrid (sharp or bitter, unpleasant) to mildly hot. Gills of short-stalked russulas are mild or only slightly acrid. Some milk caps look similar, but a drop of ‘milk’ will show when their gills are broken.
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The white chanterelle looks superficially similar, but has thick vein-like gills on the underside of the cap. It is smaller and not as substantial as the short-stemmed russula.
Hygrophorus subalpinus
The subalpine waxy cap is somewhat similar in appearance to R. brevipes but lacks its brittle flesh, and it has a sticky, glutinous cap.
Russula vesicatoria
Has gills that often fork near the stipe attachment.
Russula 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.
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The European look-alike 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 surface ornamentation featuring prominent warts interconnected by a zebra-like pattern of ridges.
Lactifluus piperatus
The milk-cap mushroom can be distinguished from R. brevipes by the production of latex when the mushroom tissue is cut or injured.
Russula brevipes Bioactive Compounds
Sesquiterpene lactones are a diverse group of biologically active compounds that are being investigated for their anti-inflammatory 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.
History
In 1890 American mycologist Charles Horton Peck described this species. It is classified in the subsection Lactaroideae, a grouping of similar Russula species characterized by having whitish to pale yellow fruit bodies, compact and hard flesh, abundant lamellulae (short gills), and the absence of clamp connections.
There has been considerable confusion in the literature over the naming of Russula brevipes. Some early 20th-century American mycologists referred to it as Russula delica, although that fungus was described from Europe by Elias Fries with a description not accurately matching the North American counterparts. Fries's concept of R. delica included: a white fruit body that did not change color; a smooth, shiny cap; and thin, widely spaced gills. To add to the confusion, Rolf Singer and later Robert Kühner and Henri Romagnesi described other species they named Russula delica.
In a 2012 publication, mycologist Mike Davis and colleagues suggest that western North American Russula brevipes comprise a complex of at least four distinct species. According to MycoBank, the European species Russula chloroides is synonymous with R. brevipes, although Index Fungorum and other sources consider them distinct species.
The specific epithet brevipes is derived from the Latin words brevis "short" and pes "foot", hence "short-footed".
Photo sources:
Photo 1 - Author: Ran-DL (Attribution-NonCommercial 2.0 Generic)
Photo 2 - Author: George Wesley & Bonita Dannells (Attribution-NonCommercial-NoDerivs 2.0 Generic)
Photo 3 - Author: George Wesley & Bonita Dannells (Attribution-NonCommercial-NoDerivs 2.0 Generic)
Photo 4 - Author: George Wesley & Bonita Dannells (Attribution-NonCommercial-NoDerivs 2.0 Generic)
