The boletes of Michigan, by Alexander H. Smith and Harry D. Thiers.

LECCINUM S. F. Gray
Nat. Arr. Brit. P1. 1:640. 1821. Emended Snell, 1942
Stipe ornamented with lines, points, dots, or squamules which may
be pallid or variously colored at first but by maturity becoming darker,
usually very dark brown to black, or in some species these colors are
present from the first; hymenophore typically white or pallid at first,
rarely yellow, and tube trama typically of the Boletus subtype.
Type species: Leccinum aurantiacum.
Certain species in Tylopilus, Boletellus, and Boletus sect. Subtomentosi have rather pronounced stipe ornamentation as described
above with the exception that it does not blacken or become dark
brown as the stipe ages. The species of Leccinum in Michigan are numerous and varied. Much still remains to be done relative to their taxonomy
and classification. Only the more readily recognized species are included
here.
KEY TO SECTIONS
1. Pileus margin extending beyond the tubes as a sterile membrane at first
and breaking into segments as the pileus expands.......... Sect. Leccinum
1. Young pileus not with a distinct sterile margin extending beyond the
tubes....................................... 2
2. Pileus trichodermium containing elements with rather numerous short
ellipsoid to subglobose cells, or the cuticular layer appearing cellular
under the microscope; or the layer composed of filamentous hyphae
with some of the cells markedly inflated............. Sect. Luteoscabra
2. Pileus cuticle of filamentous elements, only very rarely with an inflated
cell, if many short cells are present these are not greatly inflated................................... Sect. Scabra
Section LECCINUM
KEY TO STIRPES
1. An outer veil present on young pilei which breaks into flat patches as the
pileus expands, in age pileus often glabrous.............. Stirps Potteri
1. Lacking an outer veil................................... 2
2. Pileus dark gray to black or dark yellow-brown....... Stirps Obscurum
2. Pileus white, yellow, orange, red, rusty red, liver color, dull cinnamon,
or dark vinaceous-brown to vinaceous-tan.................... 3

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