Mustard Family. 15 



A hirsuta Scop. Erect, simple, 1-2 feet high, rough- pubescent or nearly 

 glabrous; root-leaves obovate or spatulate, dentate or repand, petioled; stern- 

 leaves oblong to lanceolate, sessile, auvicled; petals longer than the calyx; 

 pedicels and pods erect, immature ceeds in 2 rows. Rocky woods; May-June; 

 infrequent; Clinton, Jackson, Muscatine, Johnson, Story, Woodbury, and 

 Lyon counties. 



DRABA L. Whitlow Grass. Ours low annuals, with sessile hairy leaves, 

 and racemose white flowers. Petals 2 or more times the length of the calyx. 

 Pods oval to oblong or linear, flattened; valves nerveless. Seeds in two rows, 

 marginless. 



D. caroliniana Walt. Stem 1-5 inches high; leaves tufted, oblcng or 

 obovate, entire or rarely toothed; flowers on scape-like peduncles; raceme 

 short or corymbose in fruit; pods linear, broad, smooth, longer than the pedi- 

 cels. Sandy places; March-May; infrequent; Winneshiek, Fayette, Musca- 

 tine, Johnson, Linn, Story, and Hardin counties. 



D. cuneifo!ia Nutt. Stem 4-8 inches high, branched below, leafy; leaves 

 obovate to wedge-shaped or spatulate, toothed; raceme elongated in fruit, 

 pods oblong-linear, longer than the horizontal pedicels; March-April; 

 Reported from Scott county. 



D. vcrna L. Stems scapose, 1-5 inches high; leaves basal, tufted, oblong 

 or oblanceolate, entire or dentate; petals deeply 2-cleft. Reported from 

 Scott county. 



DENTARjA L. Toothwokt. Pepper-root. Perennials. Stem-leaves few, 

 opposite or whorled, about 3-divided, the divisions coarsely toothed or lobed. 

 Flowers large, showy, white, in terminal clusters, pedicelled Pods linear, 

 flat, valves nerveless or with a faint midcerve. 



D. laclniata Muhl. Stems 6-14 inches high, scapose; tubers several, deep 

 seated; leaves petioled, the eauline usually 3, verticillate, 3-parted, the 

 divisions lanceolate, oblong or linear, toothed or incisely lobcd; flowers white 

 or rose color. Rich woods; April^June; not uncommon, widely distributed. 



D. diphylla L. Rootstock elongated, continuous; stem leaves 2, opposite; 

 leaflets 3, ovate, crenate; flowers white. Hancock county, near Twin Lakes, 

 collected in 1882 by Prof. Shimek. The species is also given in Arthur's 

 catalogue without locality. 



CARDAMINE L. Herbs, with alternate leaves, and racemose or corymbose 

 white or purple flowers. Pods linear, flattened, pedicelled; valves veinless. 



C. rhomboidea DC. Spring Cress. Perennial, glabrous; stem 6-18 inches 

 hifh from a tuberous base; root-leaves oval or orbicular, entire or angled, 

 long-petioled; stem-leaves simple oblong or oblong-ovate, sessile to short- 

 petioled; flowers large, white; petals 3 or 4 times the length of the calyx. 

 Wet meadows; April-June; common. (C.bulbosa (Schreb.) B. S. P.) 



C purpurea (Torr.) Britton. Purple C. Stem 4-10 inches high, from 

 tuberous rootstocks; leaves similar to the preceding; flowers purple, appear- 

 ing 2 weeks before the last. Common in Johnson county. (C. rhombohleu 

 purpurea T. & G.) 



C. hirsuta L. Small or hairy Bitter C. Somewhat pubescent; leaves mostly 

 basal, pinnate, the terminal segments orbicular, entire, or few toothed, the 

 lateral obovate or narrower; the stem-leaves few, low, segments linear; 

 flowers small, white; pods linear, erect. Wet places; May-July; frequent. 



ALYSSUM L. Flowers small, yellow, racemose. Pods small, orbicular; 

 valves convex, nerveless, the margins flattened. Seeds 1-several in each cell. 



