30 THE CKUCIFER FAMILY. [Arabis. 



usually simple, and rough with short hairs. Radical leaves spreading, 

 obovate or oblong, slightly toothed ; stem-leaves generally erect, 

 oblong, or lanceolate, entire or nearly so, all, or at least the upper ones, 

 clasping the stem by short auricles. Flowers small and white. Pods 

 slender, 1 to 2 inches long, erect and crowded in a long raceme. Seeds 

 without any wing. A. sagittata, DO, Turritis hirsuta, Linn. 



On walls, banks, and rocks, common in the greater part of Europe 

 and Russian Asia, but not in high northern latitudes. Not an abundant 

 plant in Britain, although occurring in numerous localities, even in 

 the north of Scotland. Fl. summer [Var. glabrata, Syme, has nearly 

 glabrous leaves.] 



4. [A. alpina, Linn. (fig. 59). Alpine R. — Very near A. hirsuta, but 

 less stiff ; stem-leaves coarsely toothed, flowers larger and fruiting 

 racemes shorter, with more spreading pods. 



A native of the Alps and Arctic regions of Europe, Asia, and North 

 America, lately discovered by Mr. H. 0. Hart on the Cuchullin mountains 

 in Skye.] 



5. A. ciliata, Br. (fig. 60). Fringed R. — Very near A. hirsuta, but 

 not above 6 inches high ; the stem usually glabrous, and the leaves only 

 fringed with a few stiff hairs on their edge, the upper ones rounded at 

 the base and not auricled. The flowers are rather larger, and the pods 

 less erect. 



In stony and rocky places, in the mountains of central Europe. In 

 Britain only at a few stations in S. Wales and the west coast of 

 Ireland. FL summer. There is some doubt whether the British and 

 the Continental plants are the same, but probably both are mere 

 varieties of the common A. hirsuta. 



6. A. Thaliana, Linn. (fig. 61). Thale R., Thalecress, Wallcress.—A 

 slender, erect, branching annual, usually about 6 inches high, but 

 sometimes attaining a foot, clothed with short, spreading stiff hairs, 

 or sometimes nearly glabrous. Leaves mostly radical and spreading, 

 oblong, with a few coarse teeth, from J to 1 inch long. Stem-leaves few, 

 small, and sessile. Flowers small and white. Pods on spreading 

 pedicles, in slender racemes, narrow linear, varying from 4 to 5 inches 

 long to twice that length. Seeds small, the two rows blended into 

 one ; the cotyledons placed obliquely, so that the radicle is almost 

 incumbent on the back of one of them. Sisymbrium Thaliana, Hook. 



On old walls, dry banks, and stony waste places throughout Europe 

 and Russian Asia, extending into northern America. Frequent in 

 Britain. Fl. early spring, and occasionally also in summer and autumn. 

 On account of the position of the radicle this species is referred by 

 some to Sisymbrium, with which it has little else in common. 



7. A. stricta, Huds. (fig. 62). Bristol Rockcress.—A perennial, but 

 probably of few years' duration, resembling in some respects the A. 

 petraia. Radical leaves in a small spreading tuft, pinnately lobed, and 

 hispid with stiff hairs. Stems about 6 inches high, erect, nearly 

 simple, with a very few small leaves narrowed at the base. Petals 

 narrow and erect. Pods erect, about an inch long. 



The Continental distribution of this species is uncertain, as the name 

 is often given to plants quite different from ours ; but it appears to be 

 a native of limestone rocks in the mountains of western Europe. In 

 Britain only on St. Vincent's rocks, near Bristol, where it is becoming 



