Draba.] VI. CRUCIFERjE. 41 



Crucifer, is still much shorter, in proportion to its width, than in the 

 shortest Arabis. 



Flowers yellow (stiff tufted perennial) 1. D. aizoides. 



Flowers white. 

 Biennials or perennials. Pedicels short and stiff. 

 Stem with a few leaves, the radical ones spreading . 3. D. incana. 



Stem almost leafless, the radical ones tufted . . , . . 2. D. hirta. 

 Annuals. Pedicels slender, spreading. 



Stem dwarf, erect, leafless. Petals deeply divided 5. D. verna. 



Steam weak, ascending, leafy. Petals entire . . . . . 4. D. muralis. 



1. D. aizoid.es, Linn. (fig. 89). Yellow D. — Stock perennial and 

 branched, covered with closely packed leaves, forming dense tufts of 

 2 or 3 inches diameter. The leaves 3 or 4 lines long, sessile, linear, 

 of a bright green, edged with stiff white hairs. Peduncles leafless, 1 

 to 4 or even 5 inches high, bearing a few rather large yellow flowers. 

 Pods about 4 inches long, glabrous or slightly hairy, with a rather long 

 style ; the valves more convex than in the rest of the genus. 



In clefts of rocks, and stony places, in the mountain districts of 

 central and southern Europe. Long cultivated in our rock-gardens, it 

 has established itself in considerable abundance on rocks and old walls 

 about Penard Castle, near Swansea. Ft. spring. 



2. D. hirta, Linn. (fig. 90). Rock D. — Stock shortly tufted and 

 perennial, but not of long duration. Leaves crowded, 3 to 5 or 6 lines 

 long, narrow, oblong, or lanceolate, entire or slightly toothed, with a few 

 stiff, simple or stellate hairs. Peduncles usually 1 or 2 inches, and 

 leafless ; in luxuriant specimens twice as long, with 1 or 2 small ovate 

 leaves. Flowers few and small, but larger than in D. incana. Pods 2 

 to 3 lines long, on short stiff pedicels, usually slightly hoary with a 

 few very minute hairs. D. rupestris, Br. 



In the mountains of the northern or Arctic regions of Europe, Asia, 

 and North America. Rare on some of the higher mountain summits of 

 Scotland and North-west Ireland. Fl. July. The specimens with 

 slightly hoary pods (as are the Scotch ones) are by some distinguished, 

 under the name of D. rupestris, from the original D. hirta of Linnaeus 

 (not found in Britain), in which they are almost or quite glabrous. 



8. D. incana, Linn. (fig. 91). Hoary D.~ Nearly allied to D. hirta, 

 but very different in appearance. Often only a biennial, with the 

 radical leaves spreading, and seldom forming branched tufts ; the whole 

 plant hoary with short, simple, and stellate hairs. Stems erect, 6 inches 

 high or more, with several small, sessile, oblong, or lanceolate leaves. 

 Flowers small, and white. Pods 3 to 5 lines long, on short stiff pedicels, 

 glabrous, or sprinkled with a few stellate hairs ; the valves flat, or the 

 whole pod slightly twisted. D. confusa, Ehrh. 



In rocky situations, in northern and Arctic Europe and Asia, far more 

 common than D. hirta, and descending to lower elevations. Frequent 

 in the Scotch Highlands, and extending into northern England, North 

 Wales, and Ireland, where it also occurs on maritime sandhills. Fl. 

 summer. 



4. D. muralis, Linn. (fig. 92). Wall D. — A slender, erect, but weak 

 annual, from a few inches to a foot high, simple or slightly branched, 

 green, but rough with short hairs. Radical leaves spreading, ovate or 

 oblong, toothed, \ to 1 inch long. Stem-leaves smaller, ovate, clasping 

 the stem by their cordate or auricled base. Petals white, entire, and 



