SISYMBRIUM.] CRUGIFERM. 27 



Temp, and cold N. hemisphere ; rare in the Southern ; species 80. ETYM, 

 doubtful. Differs from Brassica only in the flat cotyledons, and is united 

 to Arabis by S. Thaliana. The British species present 4 types of pod, 

 represented by 1. S. Thaliana, Irio, and Sophia; 2. S. qffieinale; 3. S. 

 pijli/ceratium ; 4. S. Alliaria. 



1. S. Thalia'na, Hook. ; leaves toothed pubescent, flowers white, pods 

 spreading or ascending obscurely 4-angled. Thale-cress. 



Dry soils, ascending to 1,500 ft. in Yorkshire ; fl. May-Sept. Annual. Stem 

 6-10 in., slender, nearly leafless. Radical leaves rosulate, oblong, petioled ; 

 cauline narrow, sessile, all entire or toothed. Flowers % in. diam. ; pedicels 

 slender. Pods \-\ in., slender, curved ; seeds minute ; cotyledons usually 

 incumbent. DLSTRIB. Europe (Arctic), Asia to the Himalaya, N. Africa ; 

 introd. in N. America. 



2. S. Ir'io, L. ; leaves runcinate-toothed or pinnatifid glabrous, flowers 

 yellow, pods terete slender suberect. London Rocket. 



Old walls, &c., Btrwick-on-Tweed and Dublin ; sporadic in other places ; a 

 denizen, Watson; fl. July-Aug. Annual or biennial. Stem 1-2 ft., branched. 

 Radical leaves petioled ; lobes irregularly toothed, terminal large often 

 hastate. Flowers fa in. diam. Pods 1| in., very many, glabrous, erect, 

 strict, very slender; valves beaded, 3-nerved ; style 0; seeds oblong. 

 DISTRIB. Central and S. Europe, N. Africa, W. Asia to the Himalaya. 

 Called " London Rocket " because it sprang up abundantly after the Great 

 Fire of 1666. 



3. S. Sophi'a, L. ; leaves 2-3 -pinnatifid glabrous or downy, segments 

 narrowly linear, flowers yellow, pods slender terete ascending curved, 

 pedicels very slender. Flixweed, 



Waste places, rarer in Scotland and Ireland ; fl. June-Aug. Annual. Stem 

 1-3 ft., branched above ; branches spreading and ascending, leafy. Leaves 

 2-4 in., finely divided ; lobes spreading. Flowers | in. diam. Pods 1 in., in 



long racemes ; valves beaded, 3-ribbed ; style very short. DISTKIB. Europe 

 (Arctic), N. Africa, West Asia to the Himalaya, N. and S. America. 



4. S. officinale, L. ; leaves runcinate-toothed or -lobed hairy, flowers 

 yellow, pods in a leafless raceme subulate terete appressed to the stem. 

 'ff edge-mustard. 



Hedgebanks and waste places; fl. June-July. Stern 1-2 ft., terete, erect, 

 with spreading or redexed hairs ; branches horizontal. Leaves vari- 

 ously cut or lobed, with a tendency to a large terminal lobe. Flowers A in. 

 diam. Pods \ in., tapered from the base into the almost pungent style ; 

 pedicels short, thick. DISTRIB. Europe, W. Asia to the Himalaya, N. 

 Africa ; introd, in the U. States. 



5. S. Allia'ria, Scopoli ; leaves all petioled deltoid or reniform- 

 cordate coarsely toothed or crenate pilose beneath, pods stout long 

 4-angled, pedicels short stout. Erysimum, L. ; Alliaria, Andrz. Garlic- 

 mustard, Sauce alone, Jack by the hcdgd 



Hedgebanks, &c., ascending to near 1,000 ft. in England ; rarer in N. Scotland 

 and Ireland ; fl. May-June. Annual or rarely biennial, glabrous or with a 

 few scattered simple hairs, rank scented. Stem, 2-3 ft., decumbent at the 

 base, then flexuous, erect, simple or sparingly branched. Radical leav>s 

 often 3 in. diam., on long slender petioles, smaller and more reniform than 



