Russula atropurpurea
Description
Russula atropurpurea is a dark wine-colored mushroom, usually having a darker, almost black center. It is at first convex, but later flattens, and often has a shallow depression. The stalk (stipe) is firm and white, greying with age and the gills are cream. The flesh is said to smell of apples. It is an edible member of the genus Russula.
The mature fruit bodies shown on the left have developed concave caps that collect water during wet weather, and much of the color has washed off from areas of the cap near the rim.
When old, the fruit bodies often fade, especially towards the cap rims, but the centers remain blackish.
Common names: Purple Brittlegill, Blackish Purple Russula.
Mushroom Identification
Cap
4 to 10 cm in diameter, the caps are at first convex, flattening as the fruiting body ages and usually developing slightly depressed centers.
Red-purple near the rim, the caps are dark purple and often almost black in the center.
Flesh
The flesh beneath the cuticle is white and it crumbles easily.
Gills
Adnate or adnexed, the fairly broad, crowded gills are pale cream, darkening slightly as the fruit body ages.
Stem
10 to 20 mm in diameter and 3 to 6 cm tall, the smooth, the brittle stems are white at first but become light grey with age. There is no stem ring.
Spores
Broadly ellipsoidal to spherical, 7-9 x 6-7µm; ornamented with warts and ridges.
Spore Print
White.
Odor and Taste
Faint odor of apples; mild or fairly hot taste.
Habitat & Ecological Role
Under broad-leaf trees and pines. In common with other members of the Russulaceae, Russula atropurpurea is an ectomycorrhizal mushroom.
Reactions
FeSO4 pink-pale orange; Guaiacum positive with different rapidity and intensity; Phenol pink-torbid brownish, orange-brownish aniline on the gills.
Microscopy
Amyloid, ovoidal, spores with frustoconical warts, sub-reticulated, with connections formed by crests or thin ramified lines, (6,5) 7-8,8 (9,3) x (5,5) 6-6,8 (7,2) µm. Tetrasporic basidia, clavate, 37-54 × 9-12 µm. Fusiform cystidia, appendiculate at the apex, 60-98 × 6-11 µm. Cuticula with ramified and flexuous superficial hairs; bulky and abundant dermatocystidia, septate and often truncated at the summit.
Look-Alikes
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Variable in color sometimes mimics the appearance of Russula atropurpurea; it is much smaller, more fragile and its gills have finely-toothed edges.
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Has a red-flushed stem and it smells fishy.
Russula viscida
Differs due to a brown-yellow felt at the base of the stem turning immediately red with the KOH.
History
This brittlegill was described in 1845 by German mycologist Julius Vincenz von Krombholz (1782 - 1843), who called it Agaricus atropurpureus.
In 1893 this species was transferred to the Russula genus by another German mycologist, Max Britzelmayr (1839 – 1909).
Synonyms of Russula atropurpurea include Agaricus atropurpureus Krombh., Russula undulata Velen., Russula depallens var. atropurpurea (Krombh.) Melzer & Zvára, Russula atropurpurea var. krombholzii Singer, and Russula krombholzii Shaffer.
Russula, the generic name, means red or reddish, and indeed many of the brittlegills have red caps. The specific epithet atropurpurea is made up of the prefix atro-, which means black (or blackish), and purpurea, which of course means purple.
Photo sources:
Photo 1 - Author: Lukas from London, England (CC BY-SA 2.0)
Photo 2 - Author: Strobilomyces (CC BY-SA 4.0)
Photo 3 - Author: Lukas from London, England (CC BY-SA 2.0)
Photo 4 - Author: pinonbistro (CC BY-SA 4.0)