38 



CRUCIFER^E 



media. — A variety with double flowers is frequent in gardens under 

 the name of Yellow Rocket. — Fl. May— August. Biennial. 



2.* B. verna (American Cress), differing in a more slender 

 habit, narrower leaves, larger flotvers in a closer raceme and longer 

 pods, and flowering earlier, is a common garden escape, being 

 grown as a salad. 



5. Arabis (Rock Cress). — Herbs growing in dry places, mostly 

 local in Britain ; radical leaves spathulate; flowers small ; sepals 



short ; petals clawed ; pods 

 linear, compressed, keeled, 

 not elastic. (Name from 

 Arabia, the native country 

 of several of the species.) 



1. A. alpina (Alpine 

 Rock Cress). — A low-grow- 

 ing plant, with its cauline 

 leaves downy with branched 

 hairs, lanceolate, acute, 

 amplexicaul, toothed, and 

 its pods erect, on spread- 

 ing hairy stalks, occurs on 

 the Cuchullin Mountains 

 in the Isle of Skye. Peren- 

 nial. 



2. A. petrcea (Mountain 

 Rock Cress). — Generally 

 glabrous ; stem 3 — 8 in. 

 high, branched below ; 

 radical leaves lyrately pin- 

 natifid ; cauline leaves sub- 

 entire, stalked ; flowers 



corymbose, white, tinged with purple.— On rocks in Wales and 

 Scotland. — Fl. June— August. Perennial. 



3. A. scdbra (Bristol Rock Cress), with hispid, sinuate-dentate 

 radical leaves, sessile cauline leaves and cream-coloured flowers, 

 grows on limestone rocks at Bristol and Cheddar. — Fl. March — 

 May. Perennial. 



4. A. cilidta (Ciliate Rock Cress), with leaves smooth on both 

 sides, but fringed with forked hairs at the edges, and white 



flowers, grows on rocks by the sea near Tenby, and in the south 

 and west of Ireland.— Fl. July, August. Perennial. 



5. A. hirsiita (Hairy Rock Cress). — Hispid ; stems many, about 

 1 foot high, with numerous cauline leaves, heart-shaped at the base 



barbar£a • vulgAris {Common Winter Cress). 



