119 
With the idea of finding sufficient characters to separate Au/n- 
istera of Lamarck from Petalostemon of Michaux, I have spent some 
time in hunting up the literature of the subject. As will be seen 
from the extracts given above, botanists since the time of Michaux 
who were really acquainted with the plants which they described 
have maintained but one genus, some of them making a section 
of Kuhnistera. 
My own examinations of the different species have failed to 
establish enough constant differences to separate them into two 
genera. The plant of Walter is strikingly different in its general 
appearance from the other species, but the differences are of de- 
gree rather than of kind. All of the species have a greater or less 
number of empty bracts at the base of the flower-head. In pinata 
these are broadly ovate or almost orbicular, especially the outer 
row, which usually bears small leaflets. If these outer empty 
bracts were constant and of a different shape from the inner ones 
we would have a good character, but they are not. The outer- 
most bracts are almost obicular, the innermost oblong, with a 
gradual transition from the one to the other, as we proceed from 
the outside to within. 
_ The narrow petals and slender plumose ak: -lobes can hardly 
be considered sufficient ground for generic distinction, for as noted 
by Torrey and Gray we have these conditions in several other 
species, although no other species has the calyx-lobes so long in 
proportion to the length of the tube. 
Unless better and more constant characters can be found to 
keep up to distinct genera, the latter name of Petalostemon Michaux 
must give way to Ku/nistera of Lamarck, as set forth by Kuntze, — 
in Rev. Gen. Pl. 192 (1891). ; ae 
The following is a provisional list of the species as known to © 
me at the present time, and is printed preliminary to a descriptive 
monograph of the genus. 
KUHNISTERA Lam. Encycl. 3: 370. 1789. 
KuuNisTERA CANDIDA (Michx.) Kuntze, Rev. Gen. Fh ew 2 
1891. ; : 
Petalostemon sdadii Michx. FI. Bor. Am. 2: 49. 1803. te 
Datea candida Poir. in Lam. Encycl. 5: 604. 1804. sac 
