The North American species of Pholiota, by Alexander H. Smith and L. R. Hesler.

Smith * Hesler

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than the presence of chrysocystidia combined with a glabrous or
nearly glabrous pileus.
It is interesting to note in this arrangement that the most clearly
defined subgenera, Flavidula and Flammuloides, are the terminal or near
terminal groups. That Hemipholiota represents the basic gene pool from
which evolutionary lines diverged, and that subg. and sect. Pholiota by
accident of typification represents a small group not too far removed from
Flavidula. Finally, the overall trend of evolution, particularly in
Hemipholiota, shows a progression toward "Geophila." Thus as we have
outlined the genus here we have used the category of subgenus to indicate the major gene-pools within the group and the major trends from
them, with, we admit, the type subgenus and section actually left at a
level that would ordinarily be regarded as a stirps, though, it must be
admitted, a central one as far as the genus as a whole is concerned.
The relationships outlined here are merely a confirmation of the
original ideas of L. Quelet (1886). It is most unfortunate that the generic
names Dryophila and Geophila are not tenable under the rules.
The problem of the relationships of smaller groups to each other is
difficult in this genus, in particular since the only evidence that can be
brought to bear on them at present is somewhat subjective as far as
macroscopic features are concerned.
The division of Flavidula into two major lines is somewhat subjective in that it is only in the extremes that the Cystodcrma-type of pileus
cutis is truly distinct from the trichodermial type. A gene change to cause
the cells to be short and wide rather than long and narrow admittedly
would not need to be very great. Hence one cannot say that P. granulosa,
for instance, originated from other species with a more or less granulose
cuticle-it might as well have arisen from a species with trichodermial
hyphae having relatively long narrow cells.
INTERGENERIC RELATIONSHIPS
In our opinion the genus Pholiota originated from Galerina or
Galerina-like species. We find in Galerina the development of an apical
pore in the basidiospores, and all degrees of development from a thin
spot termed a callus to a pore which in a few species is broad enough to
cause the apex to be obscurely truncate-in other words a pore about the
size found in most species of Pholiota. In Galerina we also find the subhymenium gelatinizing in a few smooth spored species. The same may be
said for gelatinous layers in the pileus cuticle but we do not consider
this as important in intergeneric relationships as the others because most
genera of Agarics show some degree of cuticle gelantinization. To us the
important feature between the two genera is the shift in emphasis of the
important characters.