MUSTARD PLANTS 367 



scaly or toothed, aromatic or with cress-like taste: stems erect, unbranched, 

 leafless below, with 2 or 3 palmately divided or compound leaves on petioles ; 

 near the middle: fruit a linear silique, flattened, valves not nerved, with 1 

 row of seeds in each cell; seeds not winged. 



D. diphylla, Michx. Crinkle-root. Pepper-root. Stem erect, from a 

 toothed rootstock: leaves usually 2: leaflets 3-parted, wide-ovate, with 

 margins dentate: flowers white. 



D. laciniata, Muhl. Fig. 266. Rootstock deep, short, tuberous, con- 

 stricted in several places (necklace-like): stem-leaves 3, nearly verticillate, 

 deeply 3-parted into lanceolate, linear or oblong leaflets, which are lobed or 

 toothed, and some 2-cleft: flowers white or pinkish, smaller than preceding. 



6. CARDAMlNE. BITTER-CRESS. 



Very similar to Dentaria, the chief difference being in the stem, which 

 is leafy, and the leaves simple, usually more or less lobed, alternate on stem. 

 Glabrous perennials, growing in wet places and along waterways, from 

 fibrous roots or tubers (not scaly rootstocks), the flowers white or purple in 

 terminal racemes. 



C. bulbosa, BSP. Stem simple, erect, 9-18 in., from a tuber: leaves 

 simple, petioled below, ovate or rhombic-oblong in shape: petals white, 

 small, much longer than calyx. A variety purpurea, not so tall (46 in.), 

 with rose-colored flowers, appears even earlier than the type. 



7. RADfCULA. WATER-CRESS. HORSE-RADISH. 



Low, mostly aquatic or marsh plants, with pinnate or pinnatifid leaves 

 (sometimes simple); flowers small, white or yellow, with spreading sepals; 

 stamens 1-6: fruits various, short and broad (silicle) or short-cylindrical: 

 valves convex, nerveless or 1-nerved. Formerly called Nasturtium. 



R. Nasturtium-aquaticum, Britten & Rendle. Water-cress. Glabrous, 

 growing in or about water: stems spreading, rooting at the nodes: leaves 

 pinnately lobed, with 3-11 lobes, the terminal segment largest: flowers 

 small in racemes, which elongate as the fruits mature: petals white and twice 

 as long as the sepals. A favorite plant for salads. 



R. palustris, Moench. Marsh-cress. Annual or biennial, with simple, 

 fibrous roots: stem erect, 1-2 ft., glabrous or slightly pubescent: pinnately 

 lobed leaves, the upper sessile: flowers small, yellow: pods oblong or ovoid, 

 turgid, little if any longer than the pedicels. Weed in marshy places. 



R. Armoracia, Robinson. Horse-radish. Cultivated, but sometimes 

 escaped into waste grounds: perennial, the roots long and thick: root-leaves 

 large, coarse, glabrous, oblong, crenate, rarely pinnatifid, on thick petioles, 

 the stem leaves sessile, lanceolate: flowers small, petals white, longer than 

 calyx. 



8. ALfSSUM. ALYSSUM. 



Small plants, mostly trailing, with entire and small leaves: pod small, 

 orbicular, 1 or 2 seeds in each locule: flowers in elongating racemes. 



