206 PITTONIA. 
botanists to see the plant, disposed of it as a proposed new 
species, not of Draba, but of Alyssum. 
The suggestions of Thlaspi in this type lie in certain 
peculiarities of the foliage, which is of the same cut, the 
same pale hue, inclining to be purple underneath, and also 
in the fact that the sepals are thin and also purplish. But 
the pale hue of the Thlaspi herbage is owing to the presence 
of a more or less pronounced bloom, the plants being 
altogether glabrous, whereas in our plant the paleness is 
owing to a minute and peculiar appressed pubescence, in 
the characteristics of which it is most unlike that of any 
other so-called Draba. The whole genus is, by authors in 
general, credited with a stellate pubescence; but this is not 
very accurate; for a stellate pubescence properly consists of 
hairs that are both sessile and possessed of as many as five 
radiating branches. In most Drabas, at least the American 
species, the hairs are branched above the middle, or else not 
far below it, with branches most usually from two to five or 
more. Such a pubescence ought never to be described as 
stellate, but only as branched, or perhaps stellate-branched 
when the branches are numerous enough and sufficiently 
horizontal to form the conventional figure of a star. 
In our plant, however, the pubescence is unlike that of 
any other so-called Draba in that while the hairs are closely 
sessile they consist of four rays and are exactly cruciform. 
There is probably no other eruciferous type which can be 
described as having a pubescence of sessile cruciform hairs. 
Another remarkable characteristic of the present type is 
found in the existence, on almost all specimens not too old 
to show the foliage, of from two to four pairs of exactly 
opposite leaves at or near the base of the stem. I know of 
no other American crucifer that exhibits even in part an 
opposite phyllotaxy. The purple calyces and white or pink- 
ish petals are not suggestive of Draba, but of certain other 
