TETRADYNAMIA— SILIQUOSA. Arabis. 211 



side of the Avon, about a mile below the hot-wells, but sparingly. 

 Mr. JV. Clayjield and Mr. Dyer. I have also seen it on the fine 

 turf just below the hot. wells. 



Perennial. May. 



Root simply tufted, very long, tapering and fibrous, not creeping, 

 certainly perennial. Stems for the most part several, erect, or 

 ascending, from 3 to 6 inches high, round, leafy ; the central 

 one usually branched; all rough in the lower part with mostly 

 simple, spreading or deflexed, bristly hairs. Radical leaves nu- 

 merous, obtuse, dark green, purplish underneath, deeply toothed 

 or sinuated in alyrate manner, rough with simple, rarely forked, 

 rigid hairs ; stem-leaves scattered, smaller, and more entire, 

 coarsely and sparingly fringed. Fl. few, corymbose, erect, 

 cream-coloured, rather large, their petals upright. Cal. smooth, 

 reddish, scarcely if at all spreading. Pods slender, erect, straight, 

 smooth, slightly corrugated, on short smooth stalks, of vvhicli 

 some of the lowermost are accompanied by small linear leaves, 

 looking like hracteas, but not properly such. 



3. A. hispida. Alpine Rock-cress. 



Radical leaves lyrate or hastate, smooth or bristly, tufted ; 

 stem-leaves lanceolate, entire, scattered, mostly smooth. 

 Petals spreading. Root branched at the crown. 



A. hispida. Linn. Suppl. 298. Willd. Sp. Pl.v. 3. o3S. Fl. Br. 713. 

 Comp.edA.WS. Br. in Ait. H. Kew. v. 4. ]06. Hook. Scot. \99. 



A. petrasa, a, /3, y. DeCand. Syst. v. 2. 229, 230. 



A. thaliana. Crantz Austr.fasc. \.A\. l.o.f.2. 



A. crantziana. Ehrh. Herb. 78. Mllld. Sp. PL v. 3. 535. 



Sisymbrium arenosum. Linn. Fl. Suec. ed. 2. 233 ; not ofSp. PL 



Cardamine petreea. Hiids. 293. TJ'ith. 577. Light/. 347. t. 15. 

 f. 2. Jacq. Enum. 120 ; frotn the author. Host Syn.367. 



C. petrsea cambrica, nasturtii facie. Dill. Elth. 70. t. Gl./. 71. 



C. hastulata. Engl. Bot. v. 7. t. 469. FL Dan. t. 1462. 



Nasturtium petraeum Johnsoni. Raii Syn. ed. 2. 174. ed. 3. 300. 

 Pluk. Almag. 261. Phyt. t.\0\.f.3; very bad. 



Welsh Rock Cress. Petiv. H. Brit. t. 50./. 3. 



On lofty alpine rocks of Wales and Scotland, in moist places. 



First observed in various parts of North Wales, by Mr. Lhvvyd, 

 before 1696. Ray. Gathered in Scotland, by Mr. Lindesav, in 

 1728. 



Perennial. July. 



Root tapering, running deep into the ground, subdivided and 

 tufted at the crown, not at all creeping. Stem one, or more, 3 

 or 4 inches high, erect or ascending, simple or slightly branched, 

 round, leafy, frequently quite smooth, sometimes rough towards 

 the base, with simple spreading hairs. Radical leaves numerous, 

 about half an inch long, composing several lax tufts, slightly suc- 

 culent, deep green^ sometimes nearly or quite smooth, but most 



p2 



