26 



THALAMIFLOR.^ 



Arabis 



Thaliana 



(Thale Rock 



Cress) 



4. A. alpina (Alpine Rock Cress). Flowers larger 

 than in the last ; stem-leaves toothed, downy. A rare 

 species only found in the Isle of Skye. Perennial. 



5. A. ciliata (Fringed Rock Cress). Stem about 

 6 inches high, smooth ; leaves smooth on both sides, 

 fringed with hairs at the edges ; flowers white. Con- 

 fined to a few localities in South Wales and the west 

 of Ireland. Perennial. 



6. A. thaliana (Thale Rock Cress). Stem 6-12 

 inches high ; stem-leaves few ; root-leaves spreading, 

 oblong, toothed ; plant covered with short hairs ; 

 flowers small, white ; seed-pods twice as long as the 

 stalks which bear them. Walls and banks, common. 

 Fl. all the summer. Annual. 



7. A. stricta (Bristol Rock Cress). Plant about 

 6 inches high ; stem-leaves few ; root-leaves forming 

 a tuft, hairy, pinnate ; flowers yellowish white. 

 Limestone rocks near Bristol. Fl. spring. Perennial. 



8. A. petrcea (Northern Rock Cress). Stems about 

 6 inches, branched below ; root-leaves usually smooth, 

 pinnate ; flowers white with a purplish tinge. Moun- 

 tains in Scotland and Wales. Fl. summer. Perennial. 



16. Barbarea {Winter Cress) 



1. B. vulgaris (Common Winter Cress). 

 Lower leaves lyrate, the terminal lobe 

 roundish ; upper obovate, toothed. Common 

 in moist waste ground, where it may be 

 readily detected by its smooth, shining, 

 dark green leaves, and its erect angular 

 stem, bearing numerous bright yellow flowers. 

 A variety with double flowers is frequent in 

 gardens under the name of Yellow Rocket. 

 Fl. May to August. Perennial. 



2. B. prcBCOX (American Cress). Distin- 

 guished by its slender habit and narrow / 

 leaves, but it is only an escape from gardens, ^ 

 and is used for salad. Biennial. 



Botanists have distinguished several forms barbarea Vulgaris 



of B. vulgaris ; SOme of them are of rare (Common Winter Cress) 

 occurrence, and the differences by which 



they are distinguished are so slight that it is unnecessary to give 

 them here. - a 



