(MUSTARD FAMILY.) 65 



* Root perennial '; leaves simple. 



1. C. rhomboidea, DC. (SPRING CRESS.) Stems upright from a tu- 

 berous base and slender rootstock bearing small tubers, simple ; root-leaves round 

 and often heart-shaped ; lower stem-leaves ovate or rhombic-oblong, somewhat 

 petioled, the upper almost lanceolate, sessile, all often sparingly toothed ; pods 

 linear-lanceolate, pointed with a slender style tipped with a conspicuous stigma ; 

 seeds round-oral. Wet meadows and springs; common. April -June. 

 Flowers large, white. 



Var. purpurea, Torr. Lower (4 -6' high), and usually slightly pubes- 

 eut; flowers rose-purple, appearing earlier. Along streams in rich soil. 

 Western N. Y. to Md. and Wise. 



2. C. rotundifblia, Mirhx. (MOUNTAIN WATER-CRESS.) Stems branch- 

 in'/, wcalc or decumbent, making long runners; root fibrous : leaves all much 

 alike, roundish, somewhat angled, often heart-shaped at the base, petioled : 

 pods small, liuear-awl-shaped, pointed with the slender style; stigma minute; 

 seeds oval-oUom/. Cuol shaded springs, N. J. (Middletown, Willis) to Ky., 

 and southward along the mountains. May, June. Flowers white, smaller 

 than in n. 1. 



3. C. bellidifolia, L. Dwarf (2-3' high), alpine, tufted; leaves ovate, 

 entire, or sometimes with a blunt lateral tooth (4" long), on long petioles ; 

 pads 1' long, upright, linear ; style nearly none, stout. Summits of the White 

 Mountains and Katahdiu, Maine. July. Flowers 1-5, white. (Eu.) 



* # Root perennial leaves pinnate ; flowers showy. 



4. C. pratensis, L. (CUCKOOFLOWER.) Stem ascending from a short 

 rootstock, simple ; leaflets 7 - 13, those of the lower leaves rounded and stalked, 

 of the upper oblong or linear, entire, or slightly angled-toothed : petals (white 

 or rose-color) thrice the length of the calyx ; pod 9-15" long, 1" broad ; style 

 short. Wet places and bogs, Vt. to N. J , Wise., and northward; rare. 

 May. (Eu.) 



* * * Hoot mostly biennial or annual; leaves pinnate ; flowers small, white. 



5. C. hirstlta, L. (SMALL BITTER CRESS.) Glabrous or beset with 

 scattered hairs, stems (3'-2 high) erect or ascending from the spreading 

 cluster of root-leaves ; their leaflets rounded, those of the upper leaves oblong 

 or linear and often confluent, all either toothed, angled, or entire ; pods linear, 

 very narrow, erect or ascending; style variable. Wet places; common. 

 May-Julv. The ordinary form corresponds closely to the European var. 

 SYLVATICA, Gaud. The typical imperfectly developed annual form, with only 

 4 stamens and rather strict pods, occurs very rarely. A form answering to C. 

 parviflora of Europe, with mostly linear leaflets and pods often erect on spread- 

 ing pedicels, is occasionally found in drier localities. (Eu., Asia.) 



5. ARABIS, L. ROCK CRESS. 



Pod linear, flattened ; placentas not thickened ; the valves plane or convex, 

 more or less 1-nerved in the middle, or longitudinally veiny. Seeds usually 

 margined or winged. Cotyledons accumbent or a little oblique. Leaves sel- 

 dom divided. Flowers white or purple. (Name from the country, Arabia. 

 See Linn. Phil. Bot. 235.) 



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