12 CRUCIFEEAE. 



Wet places; Apvil-July; infrequent; Clinton, Muscatine, Story, Van Buren, 

 Decatur, and Page counties. {R. scssilitlora (Nutt.) A. S. H.) 



N. obtusum Nutt. Stem much branched, diffusely spreading-; leaves 

 pinnately parted or divided; flowers very small on short pedicels; pods longer 

 than the pedicels, varying from linear-oblong to short-oval. Moist places; 

 April-August; infrequent; Scott, Johnson, and Decatur counties. ( R. obtusa 

 ( Nutt.) Britt.) 

 * * Perennial; flowers white or yellow, usually large ami showy; leaves undi- 

 vided or pinnatifid. 



f Flowers white.. 



N. armoracia ( L.) Fries. Horseradish. Stem erect, 2-3 feet high, from a 

 large descending root; root-leaves long-petioled, very large, oblong, crenate, 

 sinuate or sometimes pinnatifid; cauline leaves oblong-ovate to lanceolate, 

 sessile, dentate or crenate; pods globular, or oblong, pedicels erect, many 

 times longer than the pod; style short. Frequently found near old building 

 sites and about gardens; May-June; infrequent; fruit rarely found. ( R. 

 armoracia (L.) A. S. H.) 



N. Icicustre Gray. Lahe Cress. Aquatic; stem 1-2 feet long, branched, 

 immersed leaves dissected into many filiform divisions, emersed leaves 

 oblong, obtuse or acute, entire, serrate, lobed, or pinnatifid; pedicels slender, 

 widely spreading; petals longer than the sepals; pods ovoid, 1-celled. Ponds 

 and streams; July-August; infrequent; local. Clinton and Muscatine coun- 

 ties. ( R. mnevifima (Gray) Britton.) 



N. officinale R. Br. True W. C. Stem spreading, rooting; leaves pinnate; 

 leaflets 3-11, nearly entire, rounded to oblong: petals twice the length of the 

 calyx; pods linear, about an inch long, pedicels slender, widely divergent. 

 In water or wet places; April-August; rather rare; Winneshiek, Fayette, 

 Story, and Page counties. 



f f Flowers yellow. 



N. sinuatum Nutt. Plant low, decumbent, some branched; leaves oblong, 

 pinnately cleft, divisions linear or oblong, entire or sparingly dentate; pods 

 linear-oblong, slightly curved, slender pedicelled; styles slender. Mississippi 

 and Missouri river bottoms; June-September; common; Scott, Henrv, Pag'e, 

 Pottawattomie, and Fremont counties. {R. sinuuta (Nutt.)^ A. S. H.; 



BARBAREA R. Br. Winter Cress. Pods linear-terete, obscurely 4-sided; 

 seeds marginless, one row in each cell. 



B. Vulgaris R. Br. Yellow Rocket. Stems tufted, 1-2 feet high; lower leaves 

 petioled, pinnatifid, the divisions oval or obovate, repand-toothed or entire, 

 the terminal division much larger than the lateral ones; cauline leaves 

 usually sessile, sometimes clasping by an auricled base, obovate, cut-toothed 

 or pinnatifid; pods half-inch long; pedicels one-third the length of the pods, 

 erect or spreading. Fields and waste places; May-June; infrequent; Jones, 

 Johnson, Story, Boone, and Shelby counties. (B. barharea ( L) Mac M.) 



ERYSIMUM L. Mostly biennials, with entire, toothed, or lobed leaves, and 

 small yellow flowers. Pods 4-angled, small, linear; valves keeled by a promi- 

 nent vein. Seeds m irginless, oblong, in 1 row. 



E. cheiranthoides L. Worm-seed Mustard. Stem 1-2 feet high, slender, 

 simple, erect; leaves narrowly lanceolate, entire or scarcely toothed; pods 

 about an inch long; pedicels scarcely shorter, divergent; pod and pedicels 

 angled to each other. Woods; June-August; common. 



E. asperum DC. ]{ T estern Wall-fluwer. Lower leaves lanceolate or linear. 



