88 New Genera and Species of 



somewhat bent on the cotyledons : the radicle very short, co 

 nical, pointing obliquely upwards towards the hilurm Co- 1 

 tyledons orbicular. Dissepiment 1-nerved, minutely reticu- 

 lated ; the areola) transversely linear-oblong. Herbaceous, 



annual ; leaves lyrately pinnatifid ; flowers on long subradical 

 peduncles, or in loose racemes, yellow.— Nat, Ord> Cruci- 



FERjE. 



Leavenworthia aurea, Plate 5. 



Style distinct ; embryo nearly straight. 



Root straight t simple, descending. Plant 2 — 6 inches high. Stem at first 

 short and simple, but at length branching from the base; the branches 

 assurgent, smooth. Leaves mostly radical, about 2 inches long, (including 

 the petioles) pinnatifid ; rather thick ; segments 2 — 4 parts, roundish-ob- 

 long, with a few obtuse teeth ; terminal otic much the largest, somewhat 

 orbicular. Racemes 4 — 10-fiowered. Flowers in the young plant, so- 

 litary, on long erect naked peduncles; in advanced specimens racemose 

 on the short assurgent branches. Pedicels without bracts, an inch or 

 more in length, filiform, spreading and curved upward. Calyx imbri- 

 cate in aestivation*, rather loose ; sepals oblong, obtuse, tinged with 

 purple. Petals yellow, tapering to a long cuncate base; the limb 

 truncate and somewhat cmarginatc. Stamens distinct ; filaments 

 slender ; anthers oblong. Ovarium sessile, oblong ; style short but dis- 

 tinct, straight; stigma minute, somewhat 2-loothed. Silique rather 

 more than an inch long, and nearly 2 lines in breadth, slightly torulose, 

 rather convex, obscurely nerved. Dissepiment very thin and transpa^ 

 rent, separable into two lamina, with a waved central line, or raphe, 

 running from the summit, to the base ; under a strong lens exhibiting 

 Qnastamosing veins or tubes, the interstices of which arc more or less 

 linear, and transverse, or at right angles to the longitudinal nerve. f Seeds 



* A. valvate activation of the sepala is very rare in Crucifera. It was first 

 noticed by K. Brown (Obs. on Plants collected by Oudney, &c p. 7.) in Savig- 

 niii and Ricotia, and Meyer has since detected it in Coringia, Heist, {pi. of Cau- 

 casus, p. 191.) 



t R, Brown, who first introduced the structure of the dissepiment into cha- 

 racters of the genera of Orucifcra;, aays, he expects with much confidence that it 

 will present great uniformity in strictly natural genera. He states, that " in 

 many cases, though certainly not in all, he found a resemblance in this respect in 

 more extensive groups." I have examined many Crucifora. 1 , chiefly North Ame- 



