1896] SALIX CORDATA X SERICEA 397 
sible to assign limits, since it passes so gradually either into the 
hybrid form, or into var. vestita, this latter reaching a height of 
go" and a diameter of 10". A remarkable thing is that S. sericea 
is quite rare, a pure specimen being found only amongst hun- 
dreds. I have spent a day in a region of some extent collect- 
ing undoubted hybrid forms, S. cordata., and var. vestita, without 
meeting with one pure S. sericea. This seems to prove clearly: 
that these forms are not direct crosses but races. Indeed, I 
have been struck with the tendency of the plants in different 
localities to assume a sort of family resemblance. 
The flowering period of S. sericea, its nearer hybrids, and var. 
vestifa, is about the same; that of S. cordata and of hybrids 
approaching it is some days later. Honey bees appear to be the 
chief agents of pollination. In so many of the larger hybrids 
I have observed the bark of the lower portion of the trunk to be 
check-fissured, though of moderate depth, as to incline me to 
consider this as somewhat characteristic; but I have seen the 
same occasionally in trees which would be classed as var. vestifa. 
The color is a dark gray or blackish. The bark of the S. sericea 
stem is smooth, and of light gray color. The arcuate primaries 
or looping near the margin of the leaf of S. sericea is a strong 
character, and is quite persistent in most of the hybrids; in 
other respects the venation generally resembles that of S. cordata. 
In respect to the form named S. Missouriensis Bebb, 1 may 
be pardoned for regarding it as simply a race not separable either 
, ae hag or the near hybrids, with nothing to distinguish 
ec ae apa ea perhaps, its greater size or more tree- 
fais uf if. e even this may be largely accounted for by the 
ae 25 arge trees being found growing in the richest soil. 
iis “alte the same tree-like form, with hairy leaves, and 
Gah Coa general aspect, growing in poorer soil, reduced to 
a Sei Its characters throughout are a Compronire 
the bs bin and S, sericea, with a closer leaning towards 
on = 3 hen compared with pros hybrids or races of 
ae. s the resemblance is striking. The shape, color, 
» thickness, drying color, want of gloss of the leaf, all 
