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

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The North American Species of Pholiota

time. We do know, for instance, that in some species such as P. polychroa
the spores are quite dark when moist, but we do not have properly dried
spores for comparisons. One of the major problems still to be resolved in
relation to Pholiota and the Geophila group of genera (Psilocybe, Naematoloma and Stropharia) demands critical observations on the color of the
spore deposits, since this is at present the only major distinction between
the two groups.
The spore wall for the genus is smooth by definition, but two species
are admitted in which one can find irregularities on the surface of some
of the spores (e.g. P. aurea). In thickness the wall ranges from less than
0.25,u to 0.5 fu for the majority of the species, but in a number it is from
0.5-1.5,u thick. The apical end is typically furnished with a germ pore,
but in most species it is not broad enough to affect the outline of the spore
apex as seen in optical section. In a relatively small number of species
the spore apex appears somewhat truncate to distinctly truncate because
of the width of the pore. It is the small-spored species of this group that
Singer and Smith at one time segregated as the genus Kuehneromyces.
However, we have found all degrees of the development of the germ pore
from a broad one causing the apex of the spore to appear truncate to one
so small it could hardly be discerned with a 1.4 NA oil immersion lens.
On the basis of the material we have examined the truncate spore apex
does not correlate well enough with other features of the basidiocarp to
justify a group at the rank of genus or subgenus. This was a surprize to
us, as it may be to others. We have found on some specimens that the
pore, on spores from four-spored basidia is small and does not change
the configuration of the spore apex, but on larger spores from 2-spored
basidia the pore was larger and in some the apex could be termed truncate. As we see it, the important feature is the presence of the pore, not
its width. Singer's (1963, p. 549) statement "... always with a broad
truncate germ pore" simply does not hold up if you look at the spores.
We might add that it is the spore which is truncate at the apex, not the
germ pore. Singer's statement should be read this way.
When viewed from the front (face view), spores in Pholiota are
usually elliptic. In the same mount, however, a species may exhibit a
range in form from elliptic to ovate or subovate with one or the other
usually dominating. In a large number of species the shape in face view
is rather monotonously elliptic, with a smaller percentage in a field being
subovate. In such instances little use can be made of spore-shape in the
taxonomy of the genus. On the other hand, a few notable exceptions
occur as in P. pulchella, in which the spores in optical section in face
view are distinctly ovate to broadly subfusoid. They are also rather thick
walled. In side-view (profile), it is common, in large numbers of species,
to find that the spores are inequilateral to some degree, or vary in a
different pattern to phaseoliform (bean-shaped). In our descriptions we
have tried to indicate the degree to which the spore is inequilateral by
the use of three terms: obscurely, somewhat and simply inequilateral. In