MUSTARD FAMILY 105 



Stamens 1-6. Pod short and broad or nearly linear ; seeds 

 numerous, in 2 rows in each cell.* 



1. R. Nasturtium-aquaticum B. & R. Watercress. Aquatic herbs. 

 Slems smooth, diffuse, rooting at the joints. Leaves with 3-9 rounded, 

 pinnate lobes, the terminal lobe much the largest. Racemes elon- 

 gating in fruit. Petals white, twice the length of the sepals. Pods 

 linear, ^-| in. long, on slendei', spreading pedicels. In ditches and 

 slow streams. Often used for salad.* 



2. R. sinuata Greene. Spreading Yellow Cjsess. Perennial. 

 Stems low and spreading. Leaves oblong or lanceolate, pinnately 

 cleft, the lobes obtuse. Flowers yellow, about i in. in diameter. 

 Pods linear oblong, |— | in. long. River bottoms and moist ground W. 



3. R. palustris Mcench. Yellow Watercress. Annual or bien- 

 nial. Stem erect, branched, slightly downy. Leaves irregularly 

 lyrate, the lower petioled, the upper sessile. Flowers small ; petals 

 yellow. Pods linear, spreading, longer than the pedicels. In wet 

 places.* 



4. R. Armoracia Robinson. Horse-Radish. A coarse herb, with 

 large leaves, from stout, long, cylindrical rootstocks filled with a very 

 sharp, biting juice. Basal leaves long-petioled, linear-oblong, obtuse, 

 regularly scalloped ; stem-leaves sessile. Racemes in panicles. Pods 

 obovoid, on long, slender pedicels ; seeds seldom or never ripening. 

 Probably from Europe ; cultivated and often introduced in damp 

 ground. 



X. BARBAREA R. Br. 



Mostly biennials, somewhat resembling Badicnla. Plowers 

 yellow. Pod elongated, linear, cylindrical, or somewhat 4-sided. 

 Style short. Seeds in 1 row in each cell, not margined. 



1. B. vulgaris R. Br. Wixter Cress, Yellow Rocket. Smooth, 

 with tufted stems 1-2 ft. high. Lower leaves petioled, pinnately cut, 

 with 1-4 pairs of lateral divisions and a rounded, much longer 

 terminal one ; upper leaves nearly or quite sessile. Flowers | in. in 

 diameter or less. Pods erect or spreading. Fields and waste ground. 

 Introduced from Europe into the eastern and centi'al states. 



XI. DENTARIA L. 



Stems naked below, 2-3-leaved above, from a thickish, more 

 or less knotted or interrupted rootstock. Flowers rather 

 large, in early spring. Pod lance-linear, flattish ; seeds in 1 

 row, wingless ; seedstalks broad and flat.. 



