110 
times a little broader) segments, and small white flowers in naked 
unequally few-rayed umbels. 
1. A. angustifolium Nutt. 1. c. 644. A span or two high: 
leaves 1 or 2 inches long, biternately or triternately divided, v»dth 
linear or nearly filiform segments (rarely linear-oblong) : umbels ses- 
sile; rays from an inch long to wanting; pedicels half inch long to 
wanting: fruit with narrow commissure, cordate in outline, 
long. (Fig- 119.) — Inch A latifolium Nutt. 1. c., which is the 
coarser-leaved form. Helosciadium leftofliyllum^ var. (?) latifol- 
ium Hook. & Arn. Bot. Beechey, 347. 
Hillsides, California, from San Bernardino to Mendocino county; also 
in Lower California (Miss F. E. Fish, Orcutt). FI. April and May. 
2. A. patens. One to two feet high, branching above : 
leaves (1 or 2 inches long) ternately or biternately divided, with 
long filiform segments; umbels long-peduncled ; rays and pedicels 
as in the last: fruit with broader commissure, ovate, slightly larger. 
(Fig. 120 .) — Leftocaulis patens Nutt, in DC. Prodr. iv. 107. 
PZ-. inermis Nutt, in DC. Mem. Umbel. 39. Apimn patens Wat- 
son, Bibl. Index. Polypet. 413 
From Missouri to Louisiana, Texas, and New Mexico (Wright 1106). 
FI. June. 
In Bot. Gazette, xii. 293, we referred this species provisionally to 
Leptocaulis. From that genus it differs, as was pointed out, in its thinner 
pericarp, absence of strengthening cells, frequent increase in the number 
of oil-tubes, and sulcate seed-face, all of which important characters asso- 
ciate it with Apiasfrum. 
36. MUSENIUM Nutt, in Ton*. & Gray, FI. i. 642.— 
Glabrous or scabrous dwarf resiniferous dry ground perennials, 
from thick elongated roots, acaulescent or dichotomously branch- 
ing at base, with pinnately decompound leaves, no involucre, in- 
volucels of a few narrow bractlets, and yellow or white flower's. 
This genus seems to be British American, extending into the United 
States along the Rocky Mountains. Few specimens have been collected in 
the United States, and hence herbarium material is very scanty. Prof. 
Macoun has discovered the first two species abundantly represented on the 
great plains of N. W. Terr., but M. tenuifolium remains very poorly known, 
mature fruit of it not yet having been collected. 
1. M. divaricatum Nutt. 1. c. Decumbent, glabrous: stem 
short, dichotomously branching from base: leaves bipinnatifid, 
