184 MR. NUTTALLS’ DESCRIPTIONS OF NEW 
PEUCEDANUM. 
§. *Peucetmum. Carpels with two of the lateral ribs undulately winged; vitte 
indistinct, one or two; commissure 
P. *ABROTANIFOLIUM. Somewhat pubescent, branching from the base; leaves ternately decomponud, 
ultimate segments narrowly linear; involucels about seven to nine-leaved, the leaflets palmate, 
distinct, petiolulate, nearly as long as the umbellet; fruit obovate-elliptical, with a broad, winged 
margin, and some of the inner ribs with undulated membranaceous margins. 
Like many other plants of this family, there is so striking a resemblance betwixt 
the present species and the P. carwifolium, that at first I imagined them to be the 
same, yet the character of the involucrum and the fruit is so wholly different, indeed, 
from the rest of the genus, as to require a particular section. The present is also a 
much larger plant than P. caruifolium, eighteen inches to two feet high; the leaves 
multifid, with narrow linear acute segments; petioles very short with an inflated 
base. The plant branching from the base into two or three -divisions, umbel 
subtended in the two instances out of three with a proper multifid leaf; rays of the 
umbel ten or fourteen, with several short abortive or masculine umbelets in the 
centre of the umbel ; several abortive flowers in each umbelet. Flowers yellow. 
Has. Pueblo de los Angeles, Upper California. (A single specimen, not far 
enough advanced to ascertain the ultimate character of the fruit.) 
PTEROCHITON. 
P. canescens. In fruit. P. occidentale. Torrey in Frem. Journ. p. 318. 
Culligonum canescens, Pours. Flor. Am. ii, p. 370, excluding the synonym Afriplex 
canescens. Nutt. Gen. Am. i. p. 197. 
This plant in several collections to which it was communicated, was marked 
Pterocurya canescens, as far back as 1836. At the same time I marked in the 
collection of the Academy of Natural Sciences and elsewhere, the “Pulpy-leaved 
Thorn” of Lewis and Clark, by the name of “Sarcacantuus,” the Sarcobatis of 
Nees, and Fremontia of Torrey; by the names so marked I intended to have 
published these plants. Pursh’s Calligonum, which I mistook for my Afriplex 
canescens, must have been in the collection of Lewis and Clarke, as I did not meet 
with it on the borders of the Missouri. In the same journey I collected very perfect 
specimens of the plant since called Gyvayia, which I marked in the cezllection of the. 
Academy Psilocarpus. 
Has. In the Rocky Mountains of California abundant, and also towards the 
sources of the Platte, where it forms a shrub three or four feet high. 
