CRUCIFER^E. (MUSTARD FAMILY.) 33 



nearly none. — Alpine summit of the White Mountains, New Hampshire. July. 

 — Flowers 1-5, white. Pods 1' long, turgid, the convex valves 1-nerved: so 

 that the plant might as well be an Arabis ! (Eu.) 



* * Root perennial : leaves pinnate : flowers showy. 



4. C. prafeusis, L. (Cuckoo-flower.) Stem ascending ; leaflets 7- 

 13, those of the lower leaves rounded and stalked; of the upper ones oblong or 

 linear, entire, or slightly angled-toothed ; petals (white or rose-color) thrice the 

 length of the calyx ; style short but distinct. — Wet places and bogs, Vermont 

 to New Jersey, Wisconsin, and northward; rare. May. (Eu.) 



* # * Root biennial or annual : leaves pinnate : flowers small. 



5. C hirsuta, L. (Common Bitter Cress.) Mostly smooth in the 

 United States, sometimes hairy ; leaves pinnate with 5-13 leaflets, or lyrate- 

 pinnatifid ; leaflets of the lower leaves rounded, angled or toothed ; of the upper 

 oblong or linear, often entire ; petals twice as long as the calyx (white) ; the 

 narrow pods and the pedicels upright : style shorter than the width of the pod. 

 (C. Pennsylvanica, Muhl.) — Moist places, everywhere : a small delicate variety, 

 with narrow leaflets, growing on dry rocks, is C. Virgikica, Michx. (not of 

 Hb. Linn . ) May - July. (Eu. ) 



S. ARABIS^ L. Rock Cress. 



Pod linear, flattened; the valves plane or convex, 1-nerved in the middle, oi 

 longitudinally veiny. Seeds in a single row in each cell, usually margined or 

 winged. Cotyledons accumbent. — Flowers white or rose-color. (Name from 

 the country, Arabia. See Linn. Phil. Bot., § 235.) 



* Leaves all pinnately parted: root annual or biennial. [Aspect of Cardamine.) 



1. A. L<u<loviciaaia, Meyer. Nearly glabrous, diffusely branched 

 from the base (5' -10' high) ; divisions of the almost pinnate leaves numerous, 

 oblong or linear, few-toothed or incised ; flowers very small ; pods erect-spread- 

 ing, flat (9" -12" long, 1" wide), the valves longitudinally veiny (not clastic) ; 

 seeds wing-margined. (Cardamine Ludoviciana, Hook. Sisymbrium, Nutt.) — 

 Open fields, &c, Illinois, Kentucky, and southward. April. 



* * Stem-leaves, if not the root-leaves, undivided : annuals or doubtful perennials. 



■*- Seeds wingless or slightly margined. 



2. A. lyrjata, L. Diffusely branched, low (4' -10' high), glabrous ex- 

 cept the lyrate-pinnatifid radical leaves ; stem-leaves spatulate or lanceolate, tapering 

 to the base, the upper entire; petals (white) twice the length of the calyx ; pods 

 spreading, long and slender, pointed with a short style. — Rocks. April - June. — 

 Radicle sometimes oblique. — A variety ? from Upper Michigan and northward, 

 (Sisymbrium arabidoides, Rook.) has erect pods, and the cotyledons often whol- 

 ly incumbent. 



3. A. dentata, Torr. & Gray. Roughish-pubescent, diffusely branched 

 (l°-2° high), leaves oblong, very obtuse, unequally and sharply toothed ; those 

 of the stem half-clasping and eared at the base, of the root broader and tapering 

 into a short petiole ; petals (whitish) scarcely exceeding the calyx, pods spread- 

 ing, straight, short-stalked; style scarcely any. — New York and Illinois to Virgin 



