CRUCIFERAE. 177 



entire; flowers yellow, the petals 8-10 mm. long; pods oval in outline, half as 

 thick as broad, 6-8 mm. long, acutish, finely pubescent. 



Stony places mostly on the eastern slope of the Cascade Mountains, Mul- 

 tnomah County, Oregon, Howell; Mount Adams, Washington, Flett. 



231. ALYSSUM. 



Low branching annual herbs; leaves mostly simple; flowers 

 yellow; style slender; pod ovoid or orbicular, compressed; valves 

 convex, nerveless; seeds one or two in each cell. 



Alyssum alyssoides (L.) Gouan. Annual, 10-30 cm. high, stellate- 

 pubescent throughout, usually branched from the base; leaves entire, spatulate, 

 1-2 cm. long; flowers in racemes, 5—15 cm. long; petals pale yellow, cuneate, 

 scarcely exceeding the sepals; pods orbicular, margined, notched at the apex, 

 minutely pubescent, 3 mm. broad, on spreading pedicels. 



Introduced and becoming common. 



232. DRABA. 



Low annual or perennial herbs; leaves entire or toothed; 

 flowers white or yellow, mainly in racemes ; pod oval to oblong or 

 linear, compressed parallel to the partition; valves nearly flat, 

 nerveless or faintly nerved ; seeds few to many, in two rows in the 

 cell, wingless. 



Perennials. 



Midrib of leaves becoming prominent; flowers yellow. D. glacialis. 

 Midrib of leaves not prominent; flowers white or yellow. 



Stems scapose; flowers white. D. lonchocarpa. 



Stems very leafy; flowers yellow. D. aureola. 



Annuals. 



Flowers white; petals deeply 2-cleft. D. verna. 



Flowers yellow or yellowish; petals emarginate. 



Pods 4 mm. long, crowded. D. brachycarpa. 



Pods longer, not crowded. 



Pods 6-8 mm. long, much shorter than the pedi- 

 cels. D. nemorosa. 

 Pods 8—15 mm. long, about equalling the pedi- 

 cels. D. stenoloba. 



Draba glacialis Adams. Perennial with many short clustered leafy 

 branches, the old leaves persistent on the stems; leaves linear, entire, ciliate 

 at base, stellate-pubescent, 5-15 mm. long, rigid in age and with a prominent 

 midrib; scapes 5-15 cm. long; flowers yellow; pods ovate or oblong-ovate, 

 acute, pubescent, 2-8 mm. long, on pedicels a little longer. 



On rock cliffs in the mountains. 



Draba lonchocarpa Rydb. Perennial, from a branched caudex; leave s 

 all or mostly in basal rosettes, oblanceolate, entire, minutely and densely 

 stellate-canescent, not ciliate, the midrib prominent; scapes very slender, 

 pubescent, 3-8 cm. high; flowers white; pods lanceolate, glabrous, pointed at 

 each end, 8-15 mm. long, on shorter pedicels. 



In gravelly or rocky soil in the mountains at about 2000 m. altitude. 



Draba aureola Wats. Perennial from a stout root, densely stellate-pubes- 

 cent throughout, very leafy; basal leaves oblanceolate, entire, obtuse, 8-12 



13 



