ON THE CLASSIFICATION OF ASCLEPIADS. 289 
he did not know one of those plants of the United States 
now placed, some in Acerates and others in Gomphocarpus 
by Bentham and by Gray. It was no wonder, therefore, 
_ that all these plants, as well as the types of several other 
hornless-hooded genera of ours, were early referred by their 
discoverers to Asclepias. 
And Elliott, who founded Acerates,and who lived and 
wrote before the revival of the Natural System, did not rely 
so wholly upon that negative peculiarity of the absence of 
the horn as the name which assigned the genus might seem 
to imply; for he says: “It is perhaps doubtful whether the 
absence of the horn-like appendages constitutes a sufficient 
character to establish this genus. I should have been better 
satisfied with it if it had separated the species of Asclepias 
with alternate, from those with opposite leaves."? 
If Elliott had proceeded to state what he found in the 
habit of his Acerates to mark it as unlike Asclepias, he must 
needs have mentioned (1) the strictly lateral inflorescence, 
the umbels being ranged up and down almost the whole 
length of the stem, yet none being terminal; (2) the sub- 
sessile character of the umbels; (3) the small size, narrow 
and elongated configuration, and the green color of the in- 
dividual flowers, etc. To me these several peculiarities 
make so strong an impression of the distinctness of the genus 
that I should have supported its validity if every species of 
it had been furnished with the “horn” of Asclepias. And I 
am at perfect agreement with Dr. Britton in his having trans- 
ferred the Asclepias stenophylla of Asa Gray to Acerates. It 
Issimply an Acerates with a horn to its hood; just as certain 
Californian plants of the Asclepias habit are of the genus 
Asclepias though completely destitute of the horn. 
But there is one point in the floral structure of Acerates 
by which it differs constantly from Asclepias, and that is the 
outline of that curious organ called the anther-wing. This 
MEN E Ii Penne ee Calera, ES 
? Ell. Sketch, i, 317. 
