65 
“Dalea. Corolla imperfectly papilionaceous. Stamens 9 or 10: 
the cleft tube of filaments bearing 4 of the petals about its 
middle. 
“Petalostemum. Corolla scarcely at all papilionaceous. Sta- 
mens 5; the cleft tube of filaments bearing 4 of the petals on 
its summit.” 
The United States plant mentioned above, Dalea alopecuroides 
Willd., falls distinctly under Dalea as here characterized, and so 
do all the species included by Cavanilles in the original diagnosis 
of Parosela; but the Vera Cruz plant, Psoralea Dalea L., the plant 
on which the genus Dalea (L.) Juss. was based, does not. Turn- 
ing to plate 22 in Hortus Cliffortianus, which was drawn from a 
cultivated plant from Mexican seeds, known to Linnaeus, after- 
wards raised in his own garden, and cited in his Species Plan- 
tarum, it may be seen that it represents not Dalea alopecuroides 
Willd. but D. nigra Mart. & Gal. of Mexico. The latter has 10 
stamens, but the corolla is not at all papilionaceous and 4 of the 
petals are inserted at the end of the staminal tube; they are 
wholly distinct, short-clawed, and only slightly oblique, just as 
in Petalostemen. In Parosela the wings and keel-petals are in- 
serted lower or higher up on the staminal tube, but not at the 
end thereof, the keel-petals slightly higher up than the wings. 
The blades of both are distinctly clawed, very oblique, with a 
basal lobe on the upper side, and the keel-petals are usually more 
or less united along the lower edge near the tip. 
In other words, Parosela Dalea L. combines certain characters 
of the genera Petalostemon Michx. and Parosela Cav. (Dalea as 
understood by De Candolle, Bentham and Hooker, and American 
authors generally), This species is, however, not the only one 
with the characters mentioned. There is a distinct group of 
Plants, although not very large, of the southwestern United 
States and Mexico, which agree in these respects. In habit and 
Structure of the flowers, they are almost identical with typical 
Petalostemon, except that the stamens are 9 or 10, instead of 5 
There are three ways in which the difficulty could be solv a 
1. By uniting Petalostemon and Parosela into one genus, which 
few botanists would be willing to do. 
