DICOTYLEDONOUS PLANTS 95 



n. COCHLEARIA, Tourn. 



Perennial herbs. Leaves entire or pinnate. Flowers 

 small, white. Sepals short. Petals with short claws. Pods 

 globular or ellipsoid. 



1. C. Armoracia, L. Horse-radish. A coarse herb with large 

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

 sharp, biting juice. Root-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. 



m. SISYMBRIUM, Tourn. 



Annual or biennial herbs. Radical leaves spreading ; stem- 

 leaves alternate, often eared at the base. Flowers in loose 

 racemes, usually yellow, often bracted. Pods generally nar- 

 rowly linear, cylindrical or 4-6-angled. Seeds many, ellip- 

 soid, not margined. 



1. S. canescens, Nutt. Tansy Mustard. Stem 1-2 ft. high. 

 Leaves twice pinnately cut, usually covered with grayish down. 

 Flowers very small, yellowish. Pods oblong, club-shaped, 4-angied, 

 borne on pedicels projecting almost horizontally from the stem, in 

 long racemes. Common westward. 



2. S. officinale, Scop. Hedge Mustard. Stems branching, stiff. 

 Leaves runcinate-toothed or lobed. Flowers very small, pale yel- 

 low. Pods somewhat 6-sided, awl-shaped, closely pressed against 

 the stem. An unsightly weed in waste ground, introduced from 

 Europe. 



IV. BRASSICA, Tourn. 



Branching herbs. Leaves often pinnately cut. Flowers 

 in racemes, rather large, yellow. Sepals spreading. Pods 

 nearly cylindrical, sometimes tipped with a beak which does 

 not open. Seeds globular. 



1. B. arvensis, Boiss. Charlock. Stem 1-2 ft. high; it and the 

 leaves rough-hairy. Upper leaves rhombic-toothed or no. Flowers 

 ^-| in. across, somewhat corymbed, bright yellow. Pods knotty, 

 spreading, at least ^ of each consisting of a 2-edged, 1-seeded beak. 

 A showy, troublesome weed in grain fields, introduced from Europe. 



