CL. XV.] TETRADYNAMIA SILICTJLOSA. 265 



shaped, compressed. Style none ; stigma obtuse. Pouch egg- 

 shaped, transversely compressed, entire, two-celled, two-valved ; 

 the valves deeply concave ; partition membranous, elliptical, 

 parallel to the valves, crossing the narrowest diameter of the 

 pouch. Seeds egg-shaped, four or more in each cell. Name, 

 from subula, an awl. 314. 



1. S.aqudtica. Water Awl-ioort. Root of numerous white fibres : 

 leaves awl-shaped, spreading : flowers in a simple, stalked cluster, 

 arising from the root : petals white. Annual : flowers in July : 

 grows in shallow water, in sand or gravel, near the edges of Alpine 

 lakes : frequent Eng. Bot. vol. xi. pi. 732. Eng. Fl. vol. iii. p. 157. 



929. 



2. DRA'BA, WHITLOW-GRASS. 



Calyx of four, somewhat spreading, egg-shaped valves, equal 

 at the base. Petals spreading, with short claws. Filaments 

 awl-shaped ; anthers two-lobed. Germen egg-shaped. Style 

 very short ; stigma knobbed, flat. Pouch oblong, compressed, 

 entire, two -celled ; the valves nearly flat ; partition membra- 

 nous. Seeds several in each cell, small, roundish. Name, from 

 drabe, acrid. 315. 



1. D. verna. Common Whitlow-grass. Stem leafless ; petals 

 deeply cleft; leaves lance-shaped, toothed, hairy. Leaves ar- 

 ranged in a star-like form on the ground : flowers white, in a 

 corymbose cluster. Annual : flowers in March and April : grows 

 on walls and dry loose soil: common. Eng. Bot. vol. ix. pi. 586, 

 Eng. Fl. vol. iii. p. 158. 930. 



2. D. aizoides. Yellow Alpine Whitlow-grass. Stem leafless ; petals 

 slightly notched, twice as long as the calyx ; leaves lance-shaped, 



stiff, glossy, fringed and keeled. Flowers of a bright-yellow 



colour : pouch with a long style. Perennial : flowers in March and 

 April : grows on walls and rocks about Swansea, Wales. Eng. Bot. 

 vol. xviii. pi. 1271. Eng. FL vol. iii. p. 158. 931. 



3. D. rupestris. Hairy Whitlow-grass. Stem nearly leafless ; petals 

 undivided ; leaves lance-shaped, slightly toothed, fringed with 



simple hairs. Stalk solitary, two or three inches high, round, 



leafless, or with a single leaf, near the bottom : flowers small, white, 

 in a dense corymb. Perennial : flowers in May and June : grows 

 on high mountains in Scotland : rare. Eng. Bot. vol. xix. pi. 1338. 

 D. hirta. Eng. Fl. vol, iii. p. 159. 932. 



4. D. incdna. Twisted-podded Whitlow-grass. Stem-leaves nume- 

 rous, lanee- shaped, hoary, like the stem, with starry hairs ; pouch 



oblong, oblique or twisted, longer than the hairy flower- stalks. 



Stem from two to twelve inches high. Root-leaves arranged in a 

 star-like form: flowers numerous, white, with inversely heart-shaped 

 petals. Biennial : flowers in May and June : grows in rocky places, 

 on the mountains of Scotland, Wales, and the north of England : 

 frequent. Eng. Bot. vol. vi. pi. 388. Eng. Fl. vol. iii. p. 160. 933. 



5. D. murdlis. Speedwell-leaved Whitlow -grass. Stem branched ; 

 leaves heart-shaped, toothed, hairy ; pouch elliptical, obtuse, flat, 



shorter than the partial stalks. Stem erect, about a foot high, 



leafy, rough with starry hairs : flowers very numerous, small, white. 



Z2 



