13 



ORDER VII. CRUCIFER/E. 



Herbaceous or rarely suffruitescent plants with watery pungent juice, 

 alternate exstipulate leaves, and usually racemose white or yellow or 

 sometimes purple flowers. Sepals 4, imbricate, deciduous. Petals 4, 

 often unguiculate, the laminae spreading in the form of a cross (unequal, 

 and differently arranged in many of our Streptanthi), hypogynous, 

 deciduous. Stamens almost always tetradynamous, i. e., 4 long, 2 short 

 (except in some Streplanthi, where they are in 3 unequal pairs, and in 

 Athysanus and Heterodraba, which have them all of equal length); 1 in 

 some species reduced to 4 and even 2, hypogynous. Fruit usually a 

 silique or silicle of 2 valves which separate from a central partition 

 formed by the united placentae. Seeds attached to the outer edge of the 

 partition all around, usually forming a single row under the valves. 



* Pods indehiscent. 



Pods l-seeded, not wing-margined ................................ ATHYSANUS 3 



" " wing-margined .................................... THYSANOCARPUS 17 



se.eraLseeded, flattened { f^r^ted^.Y :::::. V. .".SSSESSJSi. 2? 



" " " terete and pointed ............................ RHAPHANUS 19 



T . >. (2 dissimilar 1-seeded joints . . CAKILE 20 



breaking transversely into | 8ev eral 1-seeded joints ....... RHAPHANUS 19 



" formed of 2 opposite 1-seeded nutlets ....................... CORONOPUS. 18 



* * Pods dehiscent from below. 



Pods obovoid, scarcely compressed .............................. CAMELINA 4 



" orbicular, flattened parallel with the partition ............. ALYSSUM 1 



" flattened contrary to the pa rt ition{ ES83!??. V^:.'. :;S,m DM W 



" oblong, linear-oblong, or slender- 5 fl. white ............... NASTURTIUM 9 



conical, turgid, slightly curved ( fl. yellow .............. KORIPA 10 



thin-walled, straight ...................................... SISYMBRIUM 14 



i j ( leaves lyrate ... ............. BARBAREA 11 



linear, 4-angled \ leayes e y ntire or runcina te ................. EBYSIMUM 12 



(beaked ..................................... BRASSICA 13 



9 ^beakless ............ . ........................ THELYPODIUM 7 



" " compressed; valves elastically dehiscent ............. CARDAMINE 8 



* * * Pods dehiscent from the apex. TROPIDOCARPUM 21 



1. ALYSSUM, Diose. Low herbs with simple leaves and more or 

 less of a stellate pubescence. Sepals equal. Petals white or yellowish. 

 Pod orbicular; valves convex, nerveless. Seeds 1 or 2 in each cell. 



1. A. alyssoides (L.), Gouan. Annual, branching from the base, 

 decumbent, ^ 1 ft. high, canescent: leaves linear-spatulate, % 1 in. 

 long: raceme rather slender, the white or pale yellow petals little exceed- 

 ing the sepals: pod slightly emarginate, little exceeding the persistent 

 sepals, 4-seeded. Naturalized about San Francisco. 



