CRUCIFERJE. (MUSTARD FAMILY.) 65 



§ 3. Petals white, much longer than the calyx : pods ovoid or globular : It an a undivided. 



or the hirer ones pinnatijid : root perennial. ( Arnioraeia.) 



7. N". lacustre, Gray, Gen. 111. 1, p. 132. (Lake CKE88.) Aquatic; 

 immersed leaves L-8-pinnately dissected into numerous capillary divisions; 

 emersed leaves oblong, entire, serrate, or pinnatifid; pedicels widely spreading; 

 pods ovoid, one-celled, a little longer than tin style. (N. natans, var. Americanum, 

 Gray. Armoracia Americana, Am.) — Lakes and rivers, N. E. New York to 

 Illinois and sonthwestward. July- Aug. — Near N. amphibium. 



8. N. Akmoracia, Fries. (Horseradish.) Root-leaves very large, ob- 

 long, crenate, rarely pinnatifid; those of the stem lanceolate; fruiting pedicels 

 ascending; pods globular (seldom formed); style very short. (Cochlearia Armo- 

 racia, L.) — Roots large and long ; — a well-known condiment. Escaped from 

 cultivation into moist ground. (Adv. from Eu.) 



2. LEAVENWORTHIA, Torr. Leavenwortiiia. 



Pod broadly linear or oblong, flat; the valves nerveless, but minutely reticu- 

 late-veined. Seeds in a single row in each cell, flat, surrounded by a wing. 

 Embryo straight ! or the short radicle only slightly bent in the direction which 

 if continued would make the orbicular cotyledons accumbent. — Little biennial 

 or hyemal annuals, glabrous and stemless, with lyrate root-leaves and short 

 one - few-flowered scapes. (Named in honor of the late M. C. Leavenworth.) 



1 . L. Michaiixii, Torr. — On flat rocks and barrens, S. E. Kentucky and 

 sonthwestward: rare. March - May. — Scapes 2' -4' high. Petals purple, 

 rose color, or nearly white, with a golden yellow or yellowish base, or rarely 

 yellow throughout? (L. aurea, Torr.), cuneate-obcordate or emarginate ; the 

 flowers rather large for the size of the plant. 



3. DENTARIA, L. Tootiiwort. Pepper-root. 



Pod lanceolate, flat, as in Cardamine, but broader. Seedstalks broad and 

 flat. Cotyledons petioled, their margins somewhat infolding each other. — 

 Perennials, with long, horizontal, fleshy, sometimes interrupted, scaly or toothed 

 rootstocks, of a pleasant pungent taste ; the simple stems leafless below, bear- 

 ing 2 or 3 petioled compound leaves about the middle, and terminated by a 

 single corymb or short raceme of large white or purple flowers. (Name from 

 dens, a tooth.) . 



1. D. diph^lla, L. Rootstock long and continuous, toothed; stem-leaves 2, 'VWrvX- . Jfr/V 

 similar to the rodictd. ones, close together, of 3 rhombic-ovate coarsely toothed . 

 leaflet- : petals white. — Rich woods, Maine to Kentucky. May. — Rootstocks ^Y^WA 

 5' -10' long, crisp, tasting like Water-Cress. ^W/3^*A 



2. D. maxima, Nutt. Rootstock interrupted, forming a string of 'thick toothed 

 tubers; stem-leaves (2-7) mostly 3 and alternate} leaflets 3, ovate, obtuse, coarsely 

 toothed and incised, often 2-3-cleft; petals pink. (D. laciniata, var. 8, Torr. 

 fr Gr.) — Northern New York (Watertown, Crawe; Utica, Paine) to Penn. : 

 rare. May. — Seldom taller, but the leaves often smaller, than in No. 1. 



3. D. heteroph^lla, Nutt. Rootstock a chain of 2 or 3 narrow-oblong and 

 obscurely toothed tubers; stem-leaves 2 or 3, alternate (rarely opposite), divided into 



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