MUSTARD FAMILY. 211 



A. Pod completely dehiscent by two valves. 



1. Pod a silique, several times (or at least three times) longer than broad. 

 Seeds in 1 row in each cell (except Sisymbrium multifidum and Arabis glabra); 



silique linear or narrowly linear. 

 Kacemes leafless. 



Filaments with one or two pairs connate (except 1 or 2 species); silique 

 compressed; sepals colored, commonly purple; petals purple varying 



to whitish, the limb narrow, commonly undulate-crisped 



2. Streptanthus. 



Filaments all distinct. 

 Silique terete, pointed with a long conical beak prolonged much beyond 



the valves; flowers large, yellow 5. Brassica. 



Silique terete, 4-sided or compressed, tipped with a short .style or 



pointless. 



Silique narrowly linear, elongated, terete or nearly so. 

 Leaves coarsely toothed or some pinnatifid or entire; flowers 



white or yellowish 1. Thelypodium. 



Leaves for the most part pinnatifid, or the lowest pinnately 



parted ; flowers yellow 3. Sisymbrium. 



Silique compressed; valves more or less 1-nerved; flowers purple, 



white or nearly white 8. Arabis. 



Silique pointed, somewhat triangular, midrib of valve conspicuous; 



flowers rather small, bright yellow 9. Barbarea. 



Silique 4-sided or flattened; valves 1-nerved; flowers large, pale 



yellow or orange 7. Erysimum. 



Silique compressed, pointed. 

 Stems sparingly leafy from a perennial, tuberous rootstock; 



flowers large, white to rose-tinted . . . 11. Dentaria. 

 Stems leafy; annual with fibrous roots and smaller flowers . . . 



12. Cardamine. 



Racemes leafy; silique obcompressed 13. Tropidocarpum. 



Seeds in 2 rows in each cell; silique terete, linear to oblong; flowers small 

 (2 lines long or less), white or yellow 10. Nasturtii'.m. 



2. Pod a silicle, roundish or little longer than broad. 



Silicle turgid, obovoid or pear-shaped; edges of the valves narrowly 



margined; flowers yellowish 15. Camelina. 



Silicle much flattened contrary to the narrow partition and 

 Obcordate or elliptical, several-seeded; flowers white or slightly 



yellowish 14. Capsella. 



Didymous, the valves separating as closed 1-seeded nutlets; flowers 



greenish-white 20. Coronopus. 



Orbicular or ovate, more or less eraarginately winged at summit; flowers 



white or apetalous 19. Lepidium. 



Silicle flattened parallel to the broad partition; flowers white 



18. Alyssum. 



B. Pod indehiscent. 



Pod elongated, breaking transversely into 1-seeded indehiscent joints. 

 Pod several-seeded, commonly with constrictions between the seeds; 



flowers showy 6. Raphanus. 



Pod 2-jointed, breaking in the middle, each joint 1-seeded; flowers small. 



4. Cakile. 



Pod broader than long, more or less didymous, the cells indehiscent but sep- 

 arating from the axis when ripe 20. Coronopus. 



Pod wholly indehiscent, roundish or obovate. 



Pod 1 to several-seeded, wingless 16. Athybanus. 



Pod 1-seeded, margined with a wing 17. Thysanocarpus . 



1. THELYPODIUM Endl. 

 Ours annual herbs. Flowers white or pale yellow (straw-colored), 

 in often dense racemes. Leaves mostly petioled, not auriculate or 

 clasping. Petals with narrow claw and linear or obovate exserted 

 limb. Stamens tetradynamous, exserted, with long and slender, 

 never united filaments. Anthers narrowly linear, sagittate, curved. 

 Stigma circular or obscurely 2-lobed, usually small. Pod elongated, 



