CRUCIFKR^. (MUSTARD FAMILV.) If) 



Order 6. CKUCIFER.E. (Mi stard Family.) 



Herbs, with a pungent watery juice, crucif(»riii corolLi, tetradynainous 

 stamens, and a 2-celled pod with 2 pari(?tal phieentte. — Sepals 4, decid- 

 uous. Petals 4. Ovary 2-celled by a partition which stn'tchcs across 

 from the placentse, rarely J -celled. Style undiviilcd <»r none; stigma 

 entire or 2-h)bed. Fruit a silique or silich', the two valves falling away 

 from the partition, which persists and is called the rephim, in a few 

 genera indchisceut. Ovules few or numerous. Flowers generally in 

 racemes and without bractlets. Leaves alternate, without stipules. 

 The mature pods are necessary for analysis. 



I. Pod delusoent, 2-valved. 



• Pod strongly compressed parallel witli the broad partition : cotyledons accumbent (i- «• 



tiie radicle and ootyledons appearing in oross-seotion thus o8)- 



■*- Pod short ; valves nerveless or faintly 1-nerved : flowers wliite or yellow. 



1. Draba* Pod ovate to oblong or linear, few to inany-seeded ; valves flut or convex. 



Seeds wingless. Low, flowers racemose. 



t- -1- Pod elongated. 

 •»* Valves nerveless ; replum thickened; seeds wingless : flowei-s white : leaves all petioled. 

 2 Cardainine. Pod moderately beaked or pointed. Stems leafy, with elongated 



racemes. 

 ■H- ++ Valves 1-nerved ; replum thin ; seeds flat, often winged or margined : flowers white to 

 purple (sometimes yellowish in Streptaiilhits) : cauline leaves (if any) sessile. 



3. Parrya. Anthers linear. Petals broadly obovate. Seeds in one or two row.s. Scape 



naked. 



4. Arabis. Anthei-s sliort, scarcely emarginate at base. Petals with a flat blade and 



claw. Calyx short or narrow, rarely colored. Seeds in 1 or 2 rows. 



5. Streptanthus. Anthers elongated, sagittate at base. Petals often without a dilated 



blade, more or less twisted or undulate, the claw channelled. Calyx dilated and 

 usually colored. Seeds in one row. 

 • ♦ Pod terete or 4-angled, slightly or not at all compressed ; seeds not margined. 

 *~ Pod long-linear (1 to 4 inches) ; valves 1-nerved ; seeds in 1 row, oblong, somewhat flat- 

 tened, cotyledons incumbent (i. e. the railide and cotyledons api)earing in cross- 

 section thus oD). Stout biennials or perennials. 



++ Flowers greenish-yellow to ])uri)le : anthers sagittate. 



6. Caulanthus. Petals with a broad claw, somewhat dilatetl almve and undulate, little 



longer than the broad sepals, greenish-yellow or purple. Filaments included. Stigma 

 nearly sessile, somewhat 2-lobed. Pod .sessile, 3 inches long or more. 



7. Thel>'po(liuin. Petals with narrow claw and flat liue.ir to rouiuled limb, much ex 



ceeding tlie narrow sepals, usually i)ink to purple. Filaments often ex8ert<*d. Styl« 

 short; stigma mostly entire. Pod sessile or shortstipittitc. 

 •»+ ^ Flowers yellow. 



8. Stanleya. Pod somowhat terete, long-stipitate. Stigma sessile, entire. Anthers not 



sa;,'ittatc, spirally coiled. Leaves entire or pinnatifld. 

 9 Erysimum. Pod 4-angled, se.ssile. Sti«ma 2-lol>ed. Anthers sagittate, not coiUni. 



Leaves narrow, entire or repandly toothed. 

 •*~ •*- Pod linear, mostly less than 1 inch long : valves 1 to 3-ner\*ed : seeds In 1 or 2 row*, 



globose to oblong : flowers usually yellow (white or pinkish in Smclon-^lin) : at least 



the lower leaves pinnatifld.' 



* Brassica, an introduced genus, may be looked for in this group, diflToring from the other 

 genera in its nearly terete pod with a !ong stout l)eak, cI'>bose seeds with the cotyledon* 

 infolding the radicle, and long sagittate anthei-s. See foot-note, p. 23 



