e ' 
on 
TETRADYNAMIA,. SILICULOSA. aa 
ets small and yellowish; silique eltiptic-oblong, pubescent. 
Flowering in May. On the gravelly hills of the Missouri, 
from the river Platte to Fort Mandan; rare. 6. insana: 
7. Arabis. 
_ Almost exclusively an European genus. 
452. ALYSSUM. E. (Gold of Pleasure.) ~ 
Filaments of 2 of the stamina often internal. 
ly toothed near the base. Silicle 2-celled, en- 
tire, acuminated with the style, mostly pubes- 
cent,.subelliptic or globose. 
An obscurely defined. genus. Most of the species as. 
in Arabdis ave furnished with a divided or stellate pubes- 
cence; stems suffruticose as well as; herbaceous; leaves 
generally entire, flowers often yellow, the species with 
this colour are said to be those only which produce the 
denticulated filaments, (an American species with yel- 
low flowers, and inftated globose pods, is totally desti- 
tute “ed this distinction and yet unquestionably an /lys- 
sum. 
Specres. 1. A. * dentatum. Stem erect, and herba-- 
__ Rous, recemes paniculate, axillary; radical leaves subrun- 
~ Ci toothed, and somewhat asperate, cauline linear- 
ceolate, sessile, nearly smooth, and partly entire; silicle 
elliptic, compressed, pubescent and contorted, termina- 
ted by a style nearly its length; peduncle longer than the 
silicle. Draba Arabisans, Px. not of Michaux? A plant so 
distinct, could scarcely bear comparison with Draéa inca- 
na. Ons. Perennial or nearly so; (Ihave befere me speci- 
mens clothed with the vestigia of 3 years.) Pubescence 
thin and not communicating any thing of a hoary appear- 
ance so common in this genus, hairs with only 4 rays, or 
decussated at right angles. Leaves all lanceolate and acute, 
those of the stem remote. Seeds brown, elliptic, and 
compressed, scarcely margined. Flowers not seen. Has. 
On the shelvings of slate rocks; near Harper’s Ferry in 
Virginia. v. s. In Herb. Muhl. , 
2. *ludovicianum. Herbaceous and spreading; e- 
ously tomentose; stems numerous, simple, lar; leaves 
linearly spathulate, entire, obtuse, Staats silicles el- 
liptic, inflated, pubescent. MMyagrum argenteum, Px. 2.p. 
434. Has. On the high hills of the Missouri, and on the 
shelvings of rocks. Flowering in April and May. Oss. 6to 
Sinches high. Perennial. Calix oblong, erect. Petals 
_ obovate, entire, golden yellow. Filaments simple. Pec 
= 
; x 
