CLASS XV. ORDER I.J DRABA. 889 



Root long, tapering, wiih slender branched fibres. Stem erect, from 

 four to twelve inches high, round, simple or branched, hoary, with 

 starry pubescence, sometimes at the base the hair becomes long and 

 woolly. Leaves numerous, the radical ones crowded in a rose-like form, 

 lanceolate, entire, or toothed, those of the stem sessile, ovate lanceolate, 

 deeply and unequally toothed, rarely entire, ribbed, all clothed with 

 close pressed starry pubescence. Inflorescence a terminal many 

 flowered raceme, becoming much elongated in fruit. Calyx of four 

 equal concave hairy pieces. Corolla of four ovate heart-shaped petals, 

 tapering into a short claw, white. Fruit an elliptical oblong or elliptic 

 lanceolate silicula, smooth, mostly half twisted, flat, wiih somewhat 

 thickened margins, crowned by a short thick style and capitate stigma, 

 two celled, many seeded. 



Habitat. — Limestone rocks in alpine situations in Wales, the North 

 of England, Scotland, and Ireland. 



Biennial ; flowering in May and June. 



This is an extremely variable plant in size and appearance. When 

 grown upon a dry rocky situation it is not more than two or three 

 inches high, simple, and scarcely leafy; if in a wet one it is twelve 

 inches high, branched and leafy, and much stouter. 



5. D. mura'lis, Linn. (Fig. 1027.) Speechvell-leaved Whitlow Grass. 

 Stem branched and leafy ; leaves ovate, obtuse, toothed, amplexicaul ; 

 silicula elliptic, oblong, obtuse, flat, smooth, many seeded ; stigma 

 sessile. 



English Botany, t. 912 — English Flora, vol. iii. p. 161.— Hooker, 

 British Flora, ed. 4. vol. i. p. 250. — Lindley, Synopsis, p. 26. 



Root tapering, and with branched fibres. Stem erect, from six to 

 eighteen inches high, round, clothed with close starry pubescence, 

 simple, Of alternately branched, slender, leafy. Leaves ovate, rough, 

 with pubescence, strongly serrated and ribbed, the radical ones nume- 

 rous, depressed, the upper ones sessile, heart-shaped at the base, and 

 embracing the stem. Inflorescence a terminal raceme, becoming much 

 elongated in fruit. Calyx of four ovate equal pieces, smooth, or some- 

 times hairy. Corolla of four white obovate entire short clav\ed petals. 

 Stamens with simple filaments and ovate yellow anthers, of two cells. 

 Fruit a smooth ovate compressed two celled silicula, crowned by the 

 sessile obtuse stigma, each cell containing from six to eight seeds, small, 

 flat, pale brown, the pedicles of the fruit slender, spreading, smooth, 

 mostly as long again as the silicula. 



Habitat. — Rocks and walls in limestone countries, but rare ; Craven, 

 Yorkshire; Wardon Hills, Bedfordshire ; Emborough, Somersetshire; 

 Garden walls, Chelsea ; about Forfar and Edinburgh, Scotland ; 

 Blarney Castle. Ireland. 



Annual; flowering in May. 



This species we find common both on lime and sandstone rocks and 

 walls amongst the Apennines of Italy. 



