Mustard Family. 13 



somewhat petioled, dentate or entire, the upper sessile, entire or toothed; 

 flowers large; pedicels short, stout; pods elongated. Waste places; has been 

 collected near Ames, Story county; introduced. 



SISYMBRJU/W L. Mustard. Pubescent annuals or biennials, with vari- 

 ously pinnatitid leaves, and small white or yellow flowers. Pods elongated, 

 terete or flattish. Seeds oblong, in 1-2 rows. 



S. officinale ( L.) Scop. Hedge AT. Stem 1-3 feet high, erect, slender, 

 mostly simple: leaves runcinate-pinnatifld, the lobes erenate, dentate, or 

 nearly entire; pods small, pointed, appressed to the stem, constricted, nearly 

 sessile. Waste places; May-September; common. 



S. canescens Nutt. Whole plant densely canescent; stem 1-2 feet high, 

 branched; leaves twice pinnatifid, divisions small, toothed or entire, obtuse; 

 pods shorter than their horizontal slender pedicels, in long open racemes, 

 oblong, linear, or club-shaped; seeds in 2 rows in each cell. Rocky or dry 

 soil; May-July: rather frequent and wicely distributed. (Sophia pinnate 

 (Walt.) Britton.) 



S. sophia L. Similar to the preceding; pods slender, ascending; seeds in 

 1 row in each cell. Reported from Scott county. {Sophia sophia (L.) Britton.) 



S. altissimum L. Tumbling M. Stem erect, 2-4 feet high, branched, 

 glabrous; lower leaves petioled, runcinate-pinnatifid, the upper leaves short 

 petioled, pinnatifid, the segments linear or lanceolate, dentate or entire, the 

 uppermost leaves linear, bract-like; flowers yellowish; pedicels short, spread- 

 ing; pods narrowly linear, 3-4 inches long. Waste places along the railway; 

 June-September; infrequent; Allamakee, Clayton, Dubuque, Scott, Clay, and 

 Story counties. 



THEL-YPODIU/W Endl. A glabrous perennial herb, with root leaves and 

 lower ones lyrate-pinnatifid, the stem leaves ovate or ovate-lanceolate, taper- 

 ing both ways, sessile, auricled, or the lower short-petioled, sharply and some- 

 times doubly toothed, and large purplish flowers. Pods terete, an inch long, 

 on short divergent pedicels; valves nerveless. Seeds in one row, oblong, mar- 

 ginless. 



T. pinnatifidum Watson. Stem 1-3 feet high. Frequent in low woods; 

 May-June; Winneshiek, Fayette, Muscatine, Johnson, Story, and Cerro 

 G-ordo counties. (Iodunthus piuntiUlidux ( Mx.) Steud.) 



BRASSICA L. Mustaed. Introduced weeds, annual or biennial, with oppo- 

 site, incised or lyrate-pinnatifid leaves, and racemose yellow flowers. Pods 

 linear and nearly terete or 4-sided, with a long 1-seeded beak, valves 1-.") 

 nerved. Seeds in 1 row in each cell. Style persistent. Fields and waste 



places. 



B. nigra (L.) Koch. Black M. Stem 2-G feet high, erect, branched; lower 

 leaves long-petioled, with a large terminal lobe and 2 or more lateral ones, 

 dentate, somewhat spiny pubescent; flowers in a large terminal raceme; 

 pods slender, appressed. June-August; very common. 



B. sinapistrum Boiss. Wild M. English Chariot. Leaves similar to the 

 preceding but less pinnatifid, upper leaves scarcely toothed; pods knotted, 

 armed with a long 2-edged beak; valves strongly 1-nerved. May-September; 

 frequent. (B. arvensls (L.) B. S. P.) 



B. alba Boiss. White 21. Lower leaves obovate, deeply pinnatifid, the 

 upper lanceolate or oblong, dentate; pods bristly, ascending, beak sword- 

 shaped, as long as the pod, 1-seeded. Rather rare; reported from Muscatine, 

 Story, and Decatur counties. (Sliuipxis alba L.) 



