MUSTARD FAMILY. 221 



1. N. officinale R. Br. Water-cress. Stems ascending or pros- 

 trate at base and rooting at the nodes, the herbage glabrous; leaflets 

 or segments 3 to 9, ovate or nearly round, the terminal always the 

 largest, or the lowest leaves without lateral leaflets; flowers white, 2 

 to 2J lines broad; petals nearly twice the length of the sepals; 

 pods divaricately spreading, J to 1 in. long, the pedicels about as 

 long. 



Common in slow-flowing creeks and about springs in the moun- 

 tains. Naturalized. 



2. N. curvisiliqua Nutt. Wkstekn Yellow-cress. Stems 

 branching, erect or decumbent, J to IJ ft. long; herbage sparsely 

 pubescent; leaves pinnatifld or pinnately parted (the segments varying 

 from linear and commonly entire to oblong or ovate and either entire, 

 toothed or pinnatifld), mostly J to 2 in. long, or the lowest or radical 

 much longer; pods linear, terete, more or less curved, ^ to 7 lines 

 long, the pedicel J to IJ lines long. 



Frequent in stream beds, margins of pools and marshy places, from 

 San Mateo Co. and the Oakland Hills northward through the Coast 

 Kanges and the Sacramento VaUey. Exceedingly variable in foliage; 

 radical leaves of a robust plant from the Napa Biver near St. Helena 

 are bipinnatifid and 1 ft. long. The var, lyratum "Wats, has coarsely 

 toothed leaves broad above and narrowed towards the base. 



8. N. palustris DC. Marsh Ybllow-cres.s. Biennial, erect, 

 branching, 2 to 5 ft. high, usually glabrous; leaves oblong-lanceolate 

 in outline, coarsely toothed or deeply pinnatifld with the oblong lobes 

 dentate; pods oblong, turgid, 2 to 3 lines long, obtuse, the pedicels 

 nearly as long. 



Lowlands of the Sacramento Eiver. 



N. DicTYOTUM Greene, collected on Grand Island, is teratological; 

 stems more or less fasciated; pods often 3 or 4-valved and placenbe 

 3 or 4; pods at intervals crowded. 



11. DENTARIA L. Toothwort. 

 Glabrous perennials. Stems and one or two long-petioled radical 

 leaves from tuberous rootstocks, the stems rarely branched and spar- 

 ingly leafy. Flowers large, white or rose-tinted, appearing in early 

 spring. Petals with slender claws and ovate spreading limb, much 

 longer than the sepals; l^hese equal at base, erect or nearly so. Pod 

 linear, flattened parallel to the partition, stout, attenuate above into 

 the slender style, the valves and partitions not nerved; seeds wing- 

 less. (From the Latin, dens, a tooth, the rootstocks toothed in some 

 species.) 



Leaves (at least tlie cauline) trifoliate ... .l.D. integrijoUa. 



Leaves all undivided . . . . . 2. D. cardiophylla. 



1. D. integrifolia Nutt. Milk-maids. Stems mostly one from 

 the rootstock, erect, 1 ft. high, the herbage rather fleshy; radical 

 leaves simple or trifoliolate, the leaves or leaflets mostly orbicular, 

 minutely dentate, and J to 1 in. long; cauline trifoliolate, ovate to 



