14 CRUCIFERAE. 



B. compestris L. Turnip. Sometimes persists for a year or two as an 

 escape near fields where the speeies was cultivated. 



HESPERIS L. Piennial or perennial herbs, with simple, sessile, or 

 petioled. ovate or ovate-lanceolate toothed leaves, and large racemose purple 

 or white flowers. Pods spreading-, linear, cylindrical. Seeds oblong-, mar- 

 ginless. in 1 row. Stigma erect, lobed. 



h|. matronalis L. Dame's Violet. Stem 2-3 feet high, simple or somewhat 

 branched; pods 2-4 inches long. An infrequent escape from gardens; 

 reported from Fayette and Story counties. 



Arabis L. Rock CRESS. Annual or perennial herbs, with undivided or 

 pinnatifid leaves, and white or purple flowers. Pods elongated, flattened 

 parallel to the partition; valves 1-3-nerved. Style short. Seeds usually mar- 

 gined or winged, in 1 row or in 2 indistinct rows. 



* Flowers small, whitish; pods recurved; seeds broadly winged. 



A. canadensis L. Sickle-pod. Stem 2-3 feet high, erect, mostly simple, 

 smooth: stem leaves sessile, pubescent, pointed at both ends, oblong-lanceo- 

 late, obscurely veined, lower remotely toothed; petals twice the length of the 

 calyx: pods narrow. 4-0 inches long, scythe-shaped, pendulous: pedicels one- 

 half inch long, rough hairy. Woods; June-August; infrequent but well dis- 

 tributed; Winneshiek, Allamakee, Clayton, Scott, Fayette. Henry. Johnson, 

 Story. Cerro Gordo, Webster, Decatur, and Page counties. 



A. laevigata (Muhl.) Poir. Smooth R. Glabrous, glaucous, stem 1-3 feet 

 high, erect: basal leaves spatulate or obovate, dentate, petioled; stem leaves 

 sagittate-clasping, entire or toothed: petals longer than the calyx; pods nar- 

 row, long: pedicels erect or spreading. Wooded hillsides; May; Faj-ette and 

 Muscatine counties; rare. 



* * Seeds wingless, oblong or elliptical, stem branching from b<i*e. 



A. dentata T.-& G. Toothed R. Stem 1-2 feet high, pubescent; root leaves 

 on short margined petioles, obovate, dentate; stem leaves oblong, obtuse, 

 sharply and unevenly toothed, auriculate clasping: pods slender, spreading, 

 short pedicelled. Low grounds; May-June: infrequent; Winneshiek, 

 Fayette, Scott. Muscatine. Henry, Story, and Decatur counties. 



A. 'yrata L. Lyre-leaved R. Tufted, 4-12 inches high: glabrous or pube- 

 scent below; radical leaves lyrate-pinnatifid: stem leaves linear to spatulate, 

 entire or toothed; petals white, longer than the calyx: pods ascending, 

 spreading, long, slender. Rocky woods; April-July; common in N. E. Iowa: 

 Winneshiek. Allamakee, Clayton, Dubuque, and Scott counties. 



* * * Seeds In 2 indistinct rows; cauline leaves sagittate-clasping. 



A. confinis Watson. Stem 1-3 feet high, erect, somewhat glaucous: root- 

 stock running: root-leaves petioled. narrow spatulate: stem-leaves sessile, 

 lanceolate or oblong-linear, entire, or lower ones occasionally toothed; petals 

 white to rose purple, twice the length of the calyx: pods 2-4 inches long, flat, 

 pedicels and pods erect or spreading; seeds wing-margined. Rocky woods; 

 June-.Iuly: frequent; Winneshiek, Allamakee, Scott, Johnson, and Emmet 

 counties, i .1 brachycarpa ( T. & G.) Pritton.) 



A. perforata Lam. Tower Mustard. Stem 2-4 feet high, erect, glaucous 

 above, smooth: root-leaves petioled. oblanceo^ate or oblong: stem-leaves 

 sessile, entire, oblong or lanceolate: corolla yellowish white, little longer 

 than the calyx: pods narrow, 3-6 inches long: seeds marginless. Reported 

 from Benton and Johnson counties. ( A. glabra { L.) Pernh.) 



* * :> * Seeds nearly wingless, icon* simple, flowers greenish icliitc. 



