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

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North American Species of Lactarius

and should be ascertained on fresh material. Taste, in Lactarius, is
ambiguous to the extent that it is often impossible to test the latex
and context separately. For a discussion of taste see that of the latex
(p. 32).
The context is typically white to pallid or tinged with the color
of the pileus near the cuticle. But, if colored, this is worth noting.
As an example in L. indigo, L. hemicyaneus, and L. chelidonium var.
chelidonioides, the flesh is blue but in related species it is some
shade of yellow, orange-pink, or red; or in some it is white to grayish.
Only a few species, comparatively, have distinctive odors. In L.
camphoratus, one invariably detects an aromatic odor in fresh collections, and in the dried specimens the odor persists for months or even
years. It is usually described as resembling that of fenugreek. Other
species with this same aromatic to fenugreek odor include L. fragilis,
L. aquifluus, and a few others. In L. volemus and L. luteolus, the odor is
characteristically strong and fetid. In some it is nauseous or mawkish.
In L. allochrous it is described as spermatic. In some such as L. deceptivus no appreciable odor is present at first; by maturity, however, a
disagreeable odor is present and this is accentuated in the dried specimens. Unless the odor is very pronounced and qualitively distinct, it is
best used as a secondary character taxonomically. There are two reasons for this: first, the fungi themselves vary greatly in this feature
depending on the condition of the basidiocarp. Ordinarily, if the odor is
distinctive it should be present in the young basidiocarps. The situation
can become confusing if old basidiocarps are tested. Second, people
vary greatly in their ability to detect odors so that the use of such in
taxonomy is more subjective than most investigators like.
The Lamellae
The features of the lamellae worthy of note and record include
color, spacing, attachment, shape, width, and the presence or absence
of lamellulae.
Color. The more common pattern of color development is from
white to pallid in youth to some shade of yellowish, buff, or ochraceous, and often with a tinge of pinkish at maturity. In lamellae which
at maturity are colored, the spores present on the gill surfaces may affect the basic color. In some species, the gills are colored from the beginning and change markedly by maturity, as in L. occidentalis. In
many species the gills become spotted or discolored where injured.
This condition is discussed under latex (pp. 31-34).
In some members of subgenus Plinthogalus, the gill edges are
marginate, that is, colored differently from the faces. In some genera
such as Mycena this is a valid species character but in Lactarius we