MUSTARD FAMILY. 211 



A. Pod completely dehiscent by two valves. 

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

 Seeds la 1 row in each cell (except Sisymbrium multifldum and Arabis glabra)- 

 silique linear or narrowly linear. 

 Racemes leaSess. 

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

 compressed; serials colored, commonly purple; petals purple varying 



to whitish, the limb narrow, commonly undulate-crisped 



2. Stseptanthus. 

 Filaments all distinct. 

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



the valves; flowers large, yellow 5. Bkassica. 



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 pinnatiiid or entire; flowers 



white or yellowisli 1. Thelypodium. 



Leaves for the most part pinnatifid, or the lowest pinnately 



parted ; flowers.yellow 8. 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 l-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-tmted .... 11. Dentaria. 

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



12. Cardamine. 



Racemes leafy ; silique obcompressed 13. Tropidocarpum. 



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



(2 lines long or less), white or yellow . 10. Nasturtium. 



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

 Sllicle 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 emarginately 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. Athysanus. 



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 tetrad^mamous, exserted, with long and slender, 

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

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



