TETRADYNAMIA-SILICULOSA. Draba. 157 



1 . S. aquatica. Water Awl-wort. 



S. aquatica. Unn.Sp. Fl.%^^. Willd. v. 3.423, Fl.Br.676. Engl 

 Bot.v. W.t. 732. Hook. Scot. 196. Lond. t. 135. Dicks. H. Sice, 

 fuse. D. 9. FLDan.t.3D. 



S. erecta, junci foliis acutis moUibus. Rail Syn.307. 



Graminifolia aquatica, thlaspeos capitulis rotundis, septo medio si- 

 licLilam dirimente. Flak. Almag. 180. Fhyt. t. 188./. 5. 



Gramen junceum hibernicum minus, thlaspios capitulis Sherardi. 

 Moris.v.3.220.iiect.8.t.\0.f.29. 



Irish Rush Cress. Fetiv. H. Brit. t. 48. f. S. 



On the sandy or gravelly bottoms of alpine lakes, under water. 



In Lough Neagh, Ireland. Sherard. Lough Carran, Scotland. 

 Dr. Hope. In several other Scottish lakes. Hooker. Also in 

 many of the Welsh lakes. Huds. Mr. Griffith, and Rev W. 

 Bingley. 



Annual. July. 



/ioo^ of numerous, long, white, simple fibres. *S7em none. Herb 

 quite smooth. Leaves several, awl-shaped, spreading, an inch 

 or two in length. Fl. few, white, minute, in a simple, stalked, 

 radical, zigzag cluster. Fouches erect. Their partition is er- 

 roneously described in Fl. Br. and Engl. Bot. as " contrary to 

 the valves" ; whereas it is contrary to the greatest diameter of 

 the seed-vessel. 



Dr. Hooker confirms our account of the flowers being always se- 

 veral feet under water, where he observed them to be constantly 

 expanded, so that the impregnation actually takes place in that 

 element. The follen has not been examined. By the excellent 

 plate of this author, so great in botanical dissections, it appears 

 that the radicle is not closely applied to the cotyledons, but they 

 together form a curve, whose two extremities are distant from 

 each other. This I presume is expressed by cotyledones bicrnrcs 

 in Mr. Brown's generic definition. 



.M8. DRABA. Whitlow-grass. 



Linn. Gen. 333. Jnss. 240. Fl. Br. 677. Br. in Ait. H. Kew. v.4.9\. 

 DcCand Syst. v. 2. 33 1 . Lam. t. 550./. 1 , 2. Gcertn. t.\4\. 



Ero|)hilu. DeCand. Syst. v. 2. 350. 



CV//. ecpuil at the base, somewhat .spreading, cleciiliious ; 

 leaves ovate, concave. Pet, either cloven, notched or en- 

 tire, s})reading, with short claws. Filam. siini)le. .//////. 

 of 2 roundish h)bcs. (irr/n. ovate. Sfijlr very short, or 

 none. S(i<iniu capitate, (hit. Poi/c/i oblong-oval, hitorally 

 compre.s.sed, entire, tipped with tlie style or stignia, of 

 2 cells; valves nearly Hat, .separating Ironi the bottom; 

 partition membranous, of the same shape and breadth. 



