North American species of Lactarius / L. R. Hesler, Alexander H. Smith.

Subgenus Lactifuus

163

minutely velvety or pruinose, equal or tapering at the base, longitudinally ribbed or striate, solid, sometimes becoming hollow.
Spore deposit white. Spores 7.5-9(10) X 7.5-8.5 (9) 1 from revived tissue, globose or subglobose; prominences 0.4-0.8(1.0) At high;
reticulate but often with a few fine lines in addition.
Basidia 42-60 X 9-12 1, 4-spored. Pleurocystidia 48-145 X 5-13
/u, ventricose-acuminate, subulate, subfusoid, or obclavate, ~ tapered
to apex, at times constricted-moniliform, rounded or subacute, yellowish, wall usually thick (to 3 i), arising in the subhymenium or the
trama. Cheilocystidia 27-60 X 5-7(9) J,, subulate, subfusoid, obclavate, more or less thick-walled, tapered to apex and at times with
constrictions; yellowish, thin-walled subfusoid cells also present.
Gill trama of interwoven hyphae; subhymenium not markedly distinctive. Pileus trama heteromerous. Pileus cuticle a zone of cells bearing a turf of pileocystidia (16)50-112 X (1.5)4-6 A, cylindric, clavate,
flask-shaped, subfusoid, often with a slender neck, walls thin or at
times slightly thickened. Stipe cuticle a cuitis or of a layer 4-6 cells
deep of inflated cells, at outer surface giving rise to a turf of caulocystidia similar to pileocystidia; rosettes present in the cortex.
Habit, habitat, and distribution.-On soil, in deciduous woods,
apparently more rarely in coniferous woods, occasionally in sphagnum
beds (Coker, 1918; 54), eastern half of United States and southern
Canada, common; also in Europe; June to September.
Observations.-This species is sometimes confused with L. corrugis, but in the latter the pileus is more distinctly velvety, the surface
corrugated and dark brown, the odor as dried is mild, and the spores
are somewhat larger. In L. volemus var. volemus the pileus color is
variable; at times it darkens as the pileus matures and sometimes it
becomes paler. In wet weather the pileus surface tends to become
more wrinkled, in dry weather it tends to become rimose.
Taxonomic problems still remain relative to the variants of L.
volemus, especially in regard to the rugose character of the pileus
and the changing and staining of the latex. On the basis of a smaller
pileus with a rugose-reticulate margin, Peck (1885; 130) described
L. volemus var. subrugosus (which we place in synonymy with L.
corrugis). Whether this is different from L. volemus var. subrugatus
(see Neuhoff 1956; 188), we have been unable to determine. With
reference to L. volemus var. oedematopus (Fr.) Neuhoff (Neuhoff 1956;
187), we are inclined to agree with Burlingham (1908; 92) that this is
the same as var. volemus.
The pileus surface in var. volemus is typically azonate but two
collections (TENN 30165 and 35119) were subzonate. Further observations are needed to determine whether these represent a deviant
growth form or a genetically stable population deserving varietal
status. In some collections the surface of the pileus is glabrous. Our