CRUCIFERJE. (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-obloug, 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-oval. — Wet meadows and springs; common. April -June.— 

 Flowers large, white. 



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

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

 Western X, Y. to Md. and Wise. 



2. C. rotundifolia, Michx. (Mountain Water-Cress.) Stems branch- 

 ing, iveak or decumbent, making long runners; root Jibrous : leaves all much 

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

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

 seeds oval-oblong. — Cool 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. Z)zf7ar/(2-3' high), alpine, tufted; leaves ovate, 

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

 pods r long, upriglit, linear ; sti/le nearlg none, stout. — Summits of the White 

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



* * Root perennial ; leaves pinnate ; flowers showy. 



4. C. pratensis, L. (Cuckoo Flower.) 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 ; stvle 

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

 May. (Eu.) 



* * * Root mostlij biennial or annual; leaves pinnate ; flowers small, white. 



5. C. hirsuta, 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 -July. 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. EocK 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 ol)lique. — Leases sel- 

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

 See Linn. Phil. Dot. § 235.) 



