BRASSICACEAE 479 



19. DRAB A L. 



Low annual or perennial scapose or caulescent herbs, often clothed with stellate pubes- 

 cence. Leaves alternate or basal : blades entire or toothed. Flowers perfect, in racemes. 

 Sepals 4, equal. Corolla white or yellow, sometimes pink or purple : petals 4, longer 

 than the sepals. Stamens 6. Ovary sessile : style short or elongated : stigma capitate. 

 Ovules 2-several in each cavity. Silicles elliptic to linear, flat : valves nerveless. Seeds 

 in \ row in each cavity. Cotyledons usually accumbent. WHITLOW GRASS. 



Annuals or often winter-annuals : pods not spirally twisted : petals about twice as long as the sepals. 

 Petals 2-cleft. 1. D. verna. 



Petals entire, erose or emarginate. 

 Leaf-blades entire. 



Pods glabrous. 2. D. Caroliniana. 



Pods pubescent. 3. D. micrantha. 



Leaf-blades toothed. 



Pods 5-15 mm. long : sepals 2 mm. long. 



Pods linear, oblong-linear or narrowly oblong. 



Racemes elongated : pods over 7 mm. long. 4. D. cuneifolia. 



Racemes umbel-like or corymbose : pods less than 7 mm. long. 5. D. Helleri. 



Pods elliptic. 6. D. platycarpa. 



Pods 2-3 mm. long: sepals barely 1 mm. long. 7. D. brachycarpa. 



Perennial : pods spirally twisted : petals thrice as long as the sepals. 8. D. ramosimma. 



1. Draba v6rna L. Annual, acaulescent, bright green. Leaves basal ; blades spat- 

 ulate, oblanceolate or narrowly oblong, 5-15 mm. long, obtuse or acute, entire or with sev- 

 eral teeth near the apex, pubescent with stellate hairs : scapes erect or ascending, usually 

 branched at the base, glabrous : pedicels filiform, ascending, 0.5-2 cm. long : sepals oblong 

 or oval, 1 mm. long, obtuse : petals white, cuneate, 2-cleft, twice as long as the sepals : pods 

 elliptic or oblong-elliptic, or sometimes oval, 5-9 mm. long. 



In fields and waste places, widely distributed in southern British America and the United States. 

 Winter and spring. 



2. Draba Caroliniana Walt. Annual, more or less hispid, especially below. Leaves 

 approximate; blades oblong, obovate, spatulate or suborbicular, 0.5-1.5 cm. long, obtuse, 

 entire, or with several shallow teeth : scapes erect or ascending, often glabrous above, 2-10 

 cm. long: pedicels ascending or spreading, 1 8 mm. long: sepals oblong, 2-2.5 mm. long, 

 obtuse : petals white, spatulate-obovate, rounded or emarginate at the apex, about twice as 

 long as the sepals : pods linear, 7-18 mm. long, glabrous. 



In sandy soil and on rocks, Massachusetts to Minnesota, Georgia and Arkansas, Spring. 



3. Draba micrantha Nutt. Similar to D. Caroliniana in habit, but commonly more 

 branched at the base. Leaves mostly at the base of the plant ; blades spatulate to cuneate 

 or oblong, entire : scapes erect or spreading, longer than the stems : racemes abbreviated : 

 pedicels 2-4 mm. long : sepals ovate or oblong-ovate : petals white, about as large as those 

 of D. Caroliniana, or those of the later flowers much smaller or obsolete : pods linear, 12-18 

 mm. long, often slightly curved, pubescent. 



In sandy soil, Illinois to Washington, Texas and California. Spring. 



4. Draba cuneifolia Nutt. Annual, pubescent with stellate hairs. Stems 1-10 cm. 

 long, simple or branched : leaves approximate ; blades cuneate, obovate or the lower some- 

 times spatulate, 1-3 cm. long, obtuse or acutish, entire or coarsely toothed above : pedun- 

 cles erect or spreading, 3-20 cm. long : pedicels finally 2-7 mm. long, spreading or some- 

 what ascending : sepals oblong, 2 mm. long, obtuse': petals white, broadly spatulate, with a 

 broad sinus at the apex: pods linear-oblong, 8-15 mm. long, minutely pubescent with 

 simple hairs. 



In fields and on cliffs, Illinois to California, Florida and Texas. Spring. 



5. Draba H611eri Small. Annual, dwarf, scabrous-pubescent or merely puberulent 

 above. Leaves mainly basal, rather crowded ; blades spatulate to oblong, 4-11 mm. long, 

 slightly toothed, acute or acutish : scapes spreading or ascending, 1-4 cm. long, usually 

 4-8 together, rough puberulent to the top : racemes abbreviated or congested : pedicels as- 

 cending or spreading, 1-3 mm. long, puberulent like the scape : sepals oblong or ovate- 

 oblong, about 1 mm. long; petals white: pods narrowly oblong, 2-6 mm. long, minutely 

 pubescent. 



In dry or sandy soil, near Corpus Christi, Texas. Spring. 



6. Draba plat7carpa T. & G. Annual, finely pubescent all over. Leaves on the 

 lower part of the plant, but not crowded ; blades 1-2 cm. long, those of the basal and lower 

 cauline leaves cuneate to oblong, those of the upper cauline oblong-lanceolate to lanceolate, 

 acute or acutish, all more or less serrate, usually rather coarsely so : scapes slender, longer 



