^U TETRADYNAMIA-SILIQUOSA. Arabis. 



rights leafy, clothed with thick-set, spreading, or jDartly deflexed 

 hairs j branched, and less hairy, at the top. Leaves bluntish, 

 variously toothed, more or less rough with short, bristly, simple 

 or forked, prominent hairs ; the radical ones largest, obovate, 

 tapering at the base ; stem-leaves numerous, sessile, ovate-ob- 

 long. Fl. small, white. Cal. smooth, purplish. Pet. mode- 

 rately spreading. Stigma sessile. Poc/s forming very long, close, 

 smooth clusters, erect, slender, smooth ; valves with a slight 

 keel half way up, undulated from the alternate projection of the 

 seeds, which are in a single row, not a double one like Turritis. 

 This last character, confirmed by a similitude of habit, is admi- 

 rably chosen by Mr. Brown to define the genus Arahis, in con- 

 tradistinction to Turritis, whose much more numerous seeds are 

 disposed in double rows. 



6. A. Turrita, Tower Wall-cress. 



Leaves toothed, clasping the stem. Flower-stalks the length 

 of the calyx, each with a leafy bractea. Pods linear, flat, 

 thick-edged, recurved in one direction. 



A. Turrita. Linn. Sp. PI 930. Willd.v. 3.541. Fl. Br.7U. Engl. 



Bot.v.3.t.\7S. Sibth. 205. Hook. Lond.t. 176. Scot.200. Jacq. 



Enum. 1 1 8. Austr. t.W. DeCand. Syst. v. 2. 23^. 

 A. umbrosa. Craniz Austr. fasc. \.A3; not41,as in Jacq., nor 39, 



as in DeCand. after Willdenow, nor t. 3.f. 2, as in the latter. 

 Leucojum n.444. Hall. Hist. v. 1. 193 5 but not Fl. Dan. t. 62. 

 Turrita major Plateau. Clus. Hist. v. 2. 126. f. 

 Turritis major, Ger. Em. 272. f. 

 Hesperidi alpinse muriariaeve similis surrecta et magna. Bauh. 



Hist. V. 2. 881. f. 

 Brassica sylvestris, albido flore, nutante siliqua. Bocc. Mus, 81. 



t. 72. Barrel. Ic. t. 353. 

 Great Tower Mustard. Petiv. H. Brit. t. 47./. 1 1 . 



On old walls, very rare. 



On the walls of Trinity and St. John's colleges, Cambridge. Prof. 

 Martyn. On Magdalen college walls, Oxford. Sibth. On the 

 castle of Cliesh, Kinross-shire ; Mr. Arnott. Hook. 



Biennial. May. 



Root tapering, simple. Herb light green, more or less densely 

 downy all over with fine, short, soft, starry hairs. Stem a foot 

 or more in height, simple, erect, leafy. Leaves obovate, broad, 

 toothed, rather acute, but not pointed 3 the radical ones taper- 

 ing downward into footstalks ; the rest heart-shaped at the base, 

 clasping the stem ; the uppermost gradually diminished into ob- 

 long bracteas, each accompanying one of the shortjloicer-stalks. 

 Cluster corymbose, nearly or quite simple. Fl. pale sulphur- 

 coloured. Pet. with a spreading border. Glands 2 at the inside 

 of the shorter stamens, and 2 at the outside of the longer. Style 



