CRUCIFERAE (MUSTARD FAMILY) 419 



one side applied to the radicle, so that the cross-section of the seed appears thus 

 0= ; or else incumbent^ viz., the back of one cotyledon applied to the radicle, 

 thus O lU In these cases the cotyledons are plane ; but they may be folded upon 

 themselves and round the radicle, as in Brassica^ where they are condtiplicate, 

 thus 0». In Leavenworthia alone the whole embryo is straight. — Leaves 

 (except in Lunaria) alternate ; stipules none. Flowers in terminal racemes or 

 corymbs ; pedicels rarely bracted. A large and natural family, of pungent or 

 acrid, but not poisonous plants. The pods and seeds give the chief characters 

 of the genera. 



Tribe I. ALYSSEAE. Pubescence, at least in part, branched or stellate. Pods orbicular to 

 (rarely) linear, short, dehiscent, flattened parallel to a broad partition. Cotyledons mostly 

 accumbent. 



* Fruit oval, short-obloug, lanceolate, or rarely linear; seeds wingless. 



1. Draba. Petals entire, emarginate or (in § EropMla) biiid. Seeds numerous, in 2 rows in 



each cell. Pubescence stellate. 



* * Fruit orbicular or broadly elliptical. 



2. Berteroa. Petals bifid. Filaments toothed near the base. Pubescence stellate, not ap- 



pressed. Capsule-valves flat. Seeds few, winged. 



3. Lobularia. Petals entire. Filaments toothed near the base. Hairs 2-lobed, attached in the 



middle, appressfed. 



4. Alyssum. Petals entire or retuse. Pubescence stellate. Capsules orbicular; valves con- 



vex ; cells (in our species) 2-8eeded. 



Tribe II. PHYSARIeAE. Fruit short, very turgid, subglobose or didymous, dehiscent. Coty- 

 ledons accumbent. Pubescence stellate. 



5. Lesquerella. Pod globose or nearly so. 



Tribe III. LEPIDIEAE. Fruit 2-celled, dehiscent, short, strongly obcompressed (except in th€ 

 aquatic g-enus Subularia). Pubescence of simple hairs or none. 



* Pod strongly obcompressed or didymous, with narrow partition ; flowers white. 

 +- Seeds several ; cotyledons accumbent. 



6. Thlaspi. Pods orbicular, obovate or obcordate, winged. 



+• -1- Seeds solitary in the cells. 



7. Lepidium. Pods ovate or orbicular, flat, scale-shaped. 



8. Coronopus. Pods didymous ; valves rugose or tuberculate, separating at maturity from the 



little partition as 2 closed nutlets. Cotyledons incumbent, narrow. 



* * Pod ovoid or globular. 



9. Subularia. Dwarf, aquatic. Leaves awl-shaped. Flowers minute, white. 



Tribe IV. CAMELInEAE. Fruit short, scarcely longer than broad. Cotyledons Incumbent 

 Some or all of the hairs branched, 



* Pod 2-valved, dehiscent, 



10. Capsella. Pod (in ours) obcordate-triangular, wingless. Flowers white. 



11. Camelina. Pod somewhat turgid, obovoid. Flowers yellow. 



* * Pod Indehiscent. 

 V2. Keslia. Pod compreased-globose.- Flowers yellow. 



Tribe v. CAKIlEAE. Fruit transversely 2-jointed ; cells unequal, each l-seeded, the ovule in 

 the upper erect, in the lower pendulous. Cotyledons accumbent. 

 \'i. Cakile. Corolla white or purplish. Fleshy herbs. 



Tribe VI. BRASSfCEAE. Fruit elongated. Cotyledons conduplicate (folded about the radicle) 

 Hairs simple or none. 



