CRUCIFERAE. 115 



157 CARDAMINE. Bitter Cress. 



Mostly glabrous leafy-stemmed perennial herbs, growing in 

 moist places; leaves entire, lobed or divided, all petioled; 

 flowers white (in ours) ; pod elongated, compressed parallel to 

 the partition ; valves nerveless ; seeds in one row, wingless. 



Leaves all simple. C. lyallii. 

 Leaves or some of them pinnate. 



Basal leaves simple. C. vallicola. 

 Basal leaves pinnate. 



Capsules 20-30-seeded ; leaflets mostly oblong. C. pennsylvanica. 



Capsules 8-20-seeded; leaflets mostly orbicular. C. oligosperma. 



Cardamine lyallii Wats. Glabrous or sparingly pubescent; stems erect 

 from running rootstocks, 15-50 cm. high; leaves petioled, suborbicular, reni- 

 form to cordate, sinuate, 2-6 cm. broad; petals 6-8 mm. long; pods erect, 

 20-30 mm. long, on short pedicels. Along streams in the Blue Mountains. 



Cardamine vallicola Greene. Glabrous; stems erect from running root- 

 stocks; leaves all trifoliolate or some of the radical ones rarely simple; terminal 

 leaflets orbicular, coarsely crenate or even lobed, 5-8 cm. long; lateral leaflets 

 ovate, mostly entire; pods 25-30 mm. long, erect, on widely spreading pedicels 

 10 mm. long. In springy places near Spokane. 



Cardamine pennsylvanica Muhl. Glabrous or nearly so, 30-60 cm. high, 

 simple or branched; leaflets 7-13, sessile, mostly oblong, but those of the 

 lowermost leaves suborbicular; pods suberect on spreading pedicels. In 

 moist ground, especially in copses. Ambiguous forms seem to connect with 

 C. oligosperma. 



Cardamine oligosperma Nutt. Annual, erect, usually simple-stemmed, 

 15-30 cm. high, sparsely hirsute throughout or nearly glabrous; leaflets small, 

 orbicular, petiolulate, 3-5-lobed or toothed; raceme few-flowered; flowers 2 mm. 

 long; pods erect, 8-20-seeded, 12-20 mm. long. Wet places, infrequent. 



158. PHOENICAULIS. 



Low perennial herbs with branching caudex; leaves mostly 

 radical, the cauline, if present, reduced; flowers rose-colored or 

 purple, in racemes on slender scapes; sepals oblong, erect; petals 

 large, with an obovate blade and a slender claw; pod a silique, 

 compressed parallel to the partition with 1 -nerved valves; seeds 

 orbicular, winged or wingless. 



Phoenicaulis cheiranthoides Nutt. Perennial from a stout vertical root; 

 caudex usually branched and covered with the bases of dead leaves; leaves 

 mostly basal, entire, spatulate to oblanceolate, 3-10 cm. long, white with a 

 fine dense stellate pubescence; stems nearly naked, 10-20 cm. high; flowers 

 dark purple, in racemes; pods glabrous, spreading, 2-5 cm. long. On stony 

 slopes in the Blue Mountains. 



159. ARABIS. Rock Cress. 



Erect annual or perennial herbs; leaves seldom divided, the 

 cauline sessile and usually clasping and auricled at the base; 



