162 TETRADYNAMIA— SILICULOSA. Alyssum. 



Naturalized on the walls of Chelsea garden, as likewise about 

 the botanic garden Edinburgh. 



Annual. April, May. 



Very unlike all our other species. Root tapering. Stem erect, al- 

 nately branched, unless very weak, from the base, from 6 to 1 8 

 inches high, leafy, rough with minute starry hairs. Radical 

 leaves several, depressed, obovate, tapering at the base ; those 

 of the stem scattered, sessile, heart-shaped ; all strongly ser- 

 rated or toothed, and clothed with short, either simple, forked 

 or stellated, hairs. Fl. very numerous, small, white, in a little 

 dense corymbose tuft, soon lengthened out into an extremely 

 long cluster of spreading powcftes, whose stalks are either smooth 

 or hairy. Cal, as Dr. Hooker observes, generally smooth ; but 

 occasionally hairy as in Engl. Bot. Pet. obovate, entire. Style 

 scarcely any. Stigma blunt, very small. Pouch about half the 

 length of its stalk, elliptical, obtuse, flat, even and smooth, with 

 6 or 8 seeds in each cell, which, as DeCandolle remarks, are 

 twice as numerous in D. nemoralis, the pouches of which are 

 finely downy, on longer and smooth stalks, and the leaves ovate- 

 oblong. 



319. ALYSSUM. Alyssum. 



Linn. Gen. 335. Juss. 240. H. Br. 659. Br. in Ait. H. Kew. v. 4. 

 93. DeCand. Syst. i;.2.301. Lam. t.559. Gcertn. t.\A\. 



Cal. equal at the base, cup-shaped, deciduous ; leaves ovate, 

 concave, uniform. Pet. obovate, entire, or slightly notch- 

 ed, flat, spreading, with short claws. Filam. about the 

 length of the calyx, often furnished with a lateral tooth, 

 or notch. Anth. of 2 roundish lobes. Germ, orbicular, 

 or elliptical, compressed. Style short. Stigma simple, 

 small. Pouch orbicular, oval, or obovate, laterally com- 

 pressed, tipped with the style, of 2 cells ; valves flattish, 

 or tumid chiefly in the middle ; partition membranous, 

 of the same shape and breadth. Seeds 1 or 2 in each cell, 

 oval, compressed, rarely bordered ; cotyledons accum- 

 bent. 



Small herbaceous or shrubby plants, downy, or hoary, with 

 simple or starry pubescence, usually much branched and 

 leafy. Leaves undivided, mostly narrow and entire. Fl. 

 white or yellow. 



1. \.jnaritimum. Sweet Alyssum. 



Stem somewhat woody, much branched, spreading. Leaves 

 lanceolate, acute, entire, hoary with close hairs. Stamens 

 simple. Seeds solitary. 



