AND GENERA OF PLANTS. | 439 
and partly quadrangular. Pappus double, the outer a very minute paleace- 
ous crown; the inner in a single series, white, pilose and soft, slenderly 
bearded towards the base, and connected together in a circle, which is 
quickly deciduous in the mass.—An elegant, smooth, dwarf annual, from 
the plains of the Platte, with several scapoid, somewhat corymbiferous stems. 
Leaves nearly all radical, pinnatifid, or runcinate, with the segments short 
and spinulosely denticulate, in the manner of the Sow Thistle. Flowers 
yellow and conspicuous. 
Leptoseris * Sonchotdes. ©. 
Has. The plains of the Platte. Flowering in June. Four or five inches high, with a slender, 
simple, whitish tap-root. Leaves about two inches long and half an inch wide, resembling those 
of a diminutive Sow-thistle, the lateral segments short, oblong and acute; stems three or four, 
rather naked, branching from below, or only from above, producing an imperfect corymb of three 
Sepals about twelve to fifteen, one-nerved, pale green, with broad whitish margins; 
The florets minutely toothed, bright yellow, 
Stigmas filiform, 
to four eapituli. 
ealiculum similar, but very short; the scales ovate. 
exserted, about the length of the involucrum. Stem leaves small and few. 
exserted and nearly smooth, Achenium pale straw-yellow, linear, much resembling the fruit of a 
Crepis, but angular, though less so in the centre of the capitulum. Pappus deciduous, like that of 
the Thistle, in a sort of ring, or rather circle of adherence, there being no true annular receptacle. 
Flowers at first nodding. This curious plant appears almost intermediate with Sonchus and Crepis, 
but with the former it only agrees in habit, 
* LEUCOSERIS. 
Capitulum many-flowered. Involucrum broadly campanulate, i involucellate ; 
sepals distinct to the base, imbricated in one or two series, subequal, linear, 
acute, membranaceous on the margin; involucel in two or three series, sub- 
squarrose, shorter than the involucrum. Receptacle convex, naked. Flo- 
rets deeply five-cleft at the summit, the tube hirsute. Anthers bisetose at 
base. Achenium short, unequally pentangular, truncate, five-ribbed, the 
sides with one or two intermediate strie in each; the basal cicatrice four- 
lobed. Pappus double, the outer a very minute paleaceous crown; the inner 
in a single series, white, pilose and soft, slenderly bearded towards the base, 
