persisting while fruits mature; petals yellowish, broadly obovate, notched at apex, 

 barely exceeding the sepals; pedicels slender to stout, widely spreading, to 2 dm. 

 long; mature siliques thick and fleshy, broadly oblong, sessile, to 15 mm. long 

 and 1 cm. wide, valve exterior covered with vesicular trichomes; seed somewhat 

 flattened, margined. 



Heavy soils and open floodplain areas, periodically flooded, from Dimmit and 

 La Salle cos. southw. in the lower Rio Grande Valley of Tex., Feb.-Mar.; 

 endemic. 



2. Selenia dissecta T. & G. 



Mostly acaulescent, occasionally developing flowering stems, winter annual, 

 often with a well-developed root; leaves bipinnate with acute lobes, glaucous, 

 petiolate, to 1 dm. long; flowers mostly pedunculate as if on stems, then in an 

 indefinite raceme; sepals widely spreading at anthesis, with a definite hornlike 

 appendage; petals yellow, obovate to spatulate, exceeding the sepals; pedicels 

 erect to spreading, to 8 cm. long; siliques at first inflated, becoming thick and 

 fleshy at maturity, flattened parallel to septum, stipitate, to 3 cm. long, 1 cm. wide; 

 style flaring broadly at base, to 5 mm. long; seeds margined, flattened. 



Low places and playa lake margins. Big Bend region e. to Ector Co. in Tex., 

 Feb.-June; also N.M. and n.e. Mex. 



3. Selenia Jonesii Cory. 



Winter annual, branching at crown; branches decumbent, to 3 dm. long; leaves 

 bipinnate with small obtuse ultimate lobes, petiolate, to 1 dm. long; flowers both 

 pedunculate and on stems in leafy-bracted racemes; sepals tawny, oblong, with a 

 short pouchlike appendage to merely a thickened area below sepal apex; petals 

 yellow, spatulate; pedicels widely spreading, to 3 cm. long; siliques inflated, 

 subglobose, short-stipitate, rounded above and below, to 12 mm. in diameter; 

 styles 2-3 mm. long; seeds widely winged; cotyledons accumbent. 



Moist or wet swales and buffalo wallows on high prairies and plateaus of 

 w.-cen. Tex., Mar.-Apr.; endemic. 



12. Leavenworthia Torr. 



Seven species in central and southern United States. 

 1. Leavenworthia aurea Torr. 



Winter annual; leaves rosette-forming, the early ones with only an orbicular 

 entire and remote terminal blade portion, later leaves with few to several lateral 

 lobes; early and mid-season flowers on scapes 3-9 cm. long, later flowers usually 

 borne in a raceme on lateral decumbent branches; sepals 4-5 mm. long; petals 

 narrowly Ungulate, lemon-yellow to orange-yellow, shallowly emarginate, 7-10 

 mm. long; siliques strongly flattened parallel to septum, thickish, erect, 1.5-3 cm. 

 long, 4-5.5 mm. wide; styles 2-3.5 mm. long; gynophore nearly 1 mm. long; 

 seeds nearly orbicular, 3.5-4.5 mm. in diameter, strongly flattened, narrowly 

 winged; radicle of embryo straight. 



In seepage of limestone cedar glades and fossil outcrops, in s.e. Okla. 

 (Waterfall) and local near San Augustine, San Augustine Co., Tex., Mar.-May. 



13. Draba L. Whitlow-grass 



Annual, biennial or perennial herbs; stems leafy or scapose, usually pubescent 

 with simple or branched trichomes; leaves entire or dentate; racemes short to 

 elongate; petals white or yellow; silicles elliptic to linear, latiseptate, flat or some- 

 times twisted; seeds numerous, biseriate to irregularly seriate; cotyledons accum- 

 bent. 



984 



