CRUCIFER^. (mustard FAMILY.) 29 



2. S. alba. L. (White Mustard.) Siliques hispid, on spreading pedi- 

 cels, scarcely as long as the sword- sh.aped beak; seed pale brown. — With 

 the preceding. 



3. S. arvensis, L. (Charlock.) Siliques smooth, angular, knotted, 

 spreading thrice as long as the 2-edged beak; seed black. — Around 

 homesteads. 



13. DRABA, L. 



Silicle oblong or oval, flattened parallel with the broad partition. Seeds 



numerous in two rows in each cell, compressed, wingless. Cotyledons accum- 



bent. — Small herbs with entire or toothed leaves, and yellow or white flowers 



in terminal racemes. 



§ 1. DRABA. —Pe/«/s entire. 



1. D. brachycarpa, Nutt. Annual; minutel}^ downy; stems leafy, 

 simple or branciied ; radical leaves round-ovate, stalked, those of the stem 

 oblong-linear ; silicle oval, as long as the pedicel. — Middle districts of Georgia, 

 in dry soil, and westward. March - April. — Stem 2' - 6' high, Silicle 2" - 

 •3" long. Flowers white. 



2. D. Caroliniana, Walt. Annual ; stems leafy and hispid at the base, 

 smooth above ; leaves tufted, spatulate-obovate, hispid ; silicle linear-oblong, 

 two or three times as long as the pedicel. — Dry sterile soil. Feb. -April. 

 — Stems l'-3' high. Silicle 4"- 6" long. Flowers white. 



3. D. cuneifolia, Kutt. Annual; leaves obovate, wedge-shaped, or the 

 lowest spatulate, toothed; raceme somewhat elongated in fruit (I'-S'), at 

 length equalling the naked peduncle ; petals emarginate, much longer than 

 the calyx ; silicles oblong-linear, minutely hairy, longer than the horizontal 

 pedicels. — West Florida (Xuttall), and westward. March- April. 



4. D. ramosissima, Desv. Perennial; stems diffuse, pu])e.scent ; leaves 

 linear-lanceolate or the lowest oblanceolate and crowded, coarsely toothed ; 

 racemes corymbose-branched ; silicle lanceolate, flat, twisted, hairy ; style 

 slender. — Mountains of North Carolina. April - May. — Stems 4'- 8' long. 

 Flowers white. 



§ 2. EROPHILA. — Petals 2-chft. 



5. D. verna, L. Stems naked, slender (2' -4' high) ; leaves radical, ob- 

 long ; silicles oblong, smooth, shorter than the pedicels, scattered ; flowers 

 small, white. — Waste places, chiefly in the upper districts. Introduced, (l). 



• 14. LESQUERELLA, Watson. 



Silicle globular, or flattened parallel to the orbicular partition, the valves 

 nerveless. Seeds few, flat. Cotyledons aocumbent. Filaments toothless. — 

 Low herbs, pubescent or hoary with stellate hairs. Racemes many-flowered. 

 Flowers yellow. 



1. L. Lescurii, Watson. Biennial, pubescent ; .stems clustered, |° high ; 

 leaves oval or oblong, \' long, toothed, half clasping by the sagittate base, 

 the lowest narrowed in a petiole ; style half as long as the flattened hispid 

 2-8-seeded silicle; seed wing-margined. — Hills near Nashville, Tennessee. 

 April -May. 



