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. Warercress. Aquatic herbs. 
Stems smooth, diffuse, rooting at the joints. Leaves with 3-9 rounded, 
pinuate 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 slender, spreading pedicels. In ditches and 
slow streams. Often used for salad.* 
2. R. sinuata Greene. SpREADING YELLOW Cress. Perennial. 
Stems low and spreading. Leaves oblong or lanceolate, pinnately 
cleft, the lobes obtuse. Flowers yellow, about 1 in. in diameter. 
Pods linear oblong, 1-1 in. long. River bottoms and moist ground W. 
3. R. palustris Moench. 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-Rapisu. 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 Radicula. Flowers 
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. WinTER 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 3 in. in 
diameter or less. Pods erect or spreading. Fields and waste ground. 
Introduced from Europe into the eastern and central 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. 
