38 
TRIANDRIA, MONOGYNIA. 
35. CenchruSi Gen. pi* 1574. (Graminecs*) 
echinatuf. 
Involucrum laciniate, echinate, 3 — 4 flowered* 
Calix 2-valved, 2-flowered, 1 fertile the other 
sterile. Styleh\?id^ (sometimes 2). 
1. C* culm ancipital, leafy, branched. Leaves lan- 
ceolate, nerved, smooth. Sheath smooth. Spike 
lateral and terminal. Involucrums alternate lan- 
ceolate echinate pubescent, villous internally. 
CaL smooth 2-valved, 5-nerved, 1,2, 3, flowered. 
Cor. glume 2-valved, longer than the calix. Siam. 
3. Seed one round. Muhl. 
Cenchrus tribuloides. Bart. Prod. FI. Ph. 
Cockspur-grass. Hedge- hog-grass. 
There Is some confusion between this species and C . tribu- 
loides of Michaux. The plant just described, I have till lately 
mistaken for the C. tribuloides, and so called it in my Pro- 
dromus ; but, having since compared it with the C. echinatus 
of Willdenow (a specimen of which I have in my herbarium, 
marked with his own hand) ; and having received a specimen 
of the C. tribuloides, from Mr. Nuttall, which be collected on 
the sea-shore. Cape May, I find that the plant growing in this 
neighbourhood is the echinatus, though the spike is neither 
so long nor so dense as in the European plant. The C. tribu- 
loides, is, I suspect, confined altogether to the sea-coast. The 
most striking discrepancy of these two similar species, is the 
yrhite pubescence on the margin of the sheath, and the dense 
white villous glumes, in the C. tribuloides, while the C. echi- 
natus is destitute of botli. The plant described by Mr. Elliot 
under the name of tribuloides, appears to be the same brought 
by Mr. Nuttall, from Cape May. I have already said this is 
not identical with the species growing so abundantly in the 
vicinity of this city, on the Jersey side of the Delaware, unless 
its maritime situation should create the villous pubescence, 
which from analo we may admit to be probable. Close to 
Camden, not unfrequent. In the sandy road from Kaighn^s 
point towards the Haddonfield road ; and on the high sandy 
exposed banks of the Delaware, between Kaighn’s point and 
the ferry -house, opposite to Gloucester point ; abundant . 
AnniiaL August. 
