Russula betularum

Taxobox
color = lightblue
name = "Russula betularum"
status = Common

---

image_width=250px
regnum = Fungi
divisio = Basidiomycota
classis = Agaricomycetes
ordo = Russulales
familia = Russulaceae
genus = "Russula"
species = "R. betularum"
binomial = "Russula betularum"
binomial_authority = Hora
synonyms = "Russula emetica var. betularum"mycomorphbox
name = Russula betularum
whichGills = free
whichGills2 = adnexed
capShape = convex
capShape2=depressed
hymeniumType=gills
stipeCharacter= bare
sporePrintColor=white
howEdible=inedible

"Russula betularum" is a small; very pale member of the "Russula" (brittlegills) genus of fungus, that have the common name of . It is usually white to very pale pink; inedible, and grows with birch trees. It is commonly known as the Birch Brittlegill.

Taxonomy

The specific epithet "betularum" "of the birches", [cite book|author = Simpson DP| title = Cassell's Latin Dictionary | publisher = Cassell Ltd.| date = 1979|edition = 5|location = London|pages = 883| isbn=0-304-52257-0] refers to its association with birch ("Betula" species). Some sources regard it as a variety of the sickener ("R. emetica").

Description

The cap is convex to flattened, and often has a central depression. On expansion the margin becomes furrowed, and bears low warts. It is 2-5 cm (0.8-2 in) in diameter, and it peels completely. The cap ranges in colour from white; to pale pink; to deep pink, and can even be pale buff. Although more often it is white with a pale pink blush, turning pale yellow ochre in the centre. The stem is typically longer than the diameter of the cap, and is cylindrical or slightly club shaped. It is white, and very fragile. The gills are also white, and well spaced, and the spore print is white. The flesh is white and tastes hot.cite book | author = Roger Phillips | year = 2006 | title = Mushrooms | publisher = Pan MacMillan | isbn = 0-330-44237-6|pages=p. 20] It might be confused with "Russula fragilis" ( Pers.) Fr. which can be pale in colour, and occur in the same habitat. However, the latter species is only three quarters peeling; usually darker at the centre, and with purplish tones. It also has marked serrations on the gill edges.

Distribution and Habitat

"Russula betularum" appears in summer and early autumn. It is widespread in Britain, Europe, and Scandinavia, and is probably mycorrhizal with birch trees. It often grows in damp places in woodlands.

Edibility

This mushroom is inedible, and has a hot 'peppery' taste. Many bitter tasting red-capped species can cause problems if eaten raw; the symptoms are mainly gastrointestinal in nature: diarrhoea, vomiting and colicky abdominal cramps. The active agent has not been identified but thought to be sesquiterpenes, which have been isolated from the related genus "Lactarius" and from "Russula sardonia". [cite book |last=Benjamin| first= Denis R. |title=Mushrooms: poisons and panaceas — a handbook for naturalists, mycologists and physicians|pages=p. 369|publisher=WH Freeman and Company| location=New York |year=1995| isbn=0-7167-2600-9]

References