3. D. heterophlla, Nutt. Tubers near the surface, jointed, narrowly oblong or thick-clavate, prominently tubercled; leaves 3-foliolate, the leaflets distinctly petiolate, oblong-lanceolate to linear, entire to rather deeply crenate, rarely laciniate or lobed; root-leaves with ovate or lanceolate and usually lobed leaflets.--Penn. to Ky. and southward.

Blooming a little later than the last.

4. D. maxima, Nutt. Tubers jointed, strongly tubercled; stem-leaves usually alternate, 3-foliolate; leaflets ovate or oblong-ovate, coa.r.s.ely toothed and somewhat cleft or lobed.--Vt. to western N. Y. and Penn.

May.

4. CARd.a.m.nE, Tourn. BITTER CRESS.

Pod linear, flattened, usually opening elastically from the base; the valves nerveless and veinless, or nearly so; placentas and part.i.tion thick. Seeds in a single row in each cell, wingless; their stalks slender. Cotyledons acc.u.mbent, flattened, equal or nearly so, petiolate.--Mostly glabrous perennials, leafy-stemmed, growing along watercourses and in wet places. Flowers white or purple. (A Greek name, in Dioscorides, for some cress, from its cordial or cardiacal qualities.)

[*] _Root perennial; leaves simple._

1. C. rhomboidea, DC. (SPRING CRESS.) _Stems upright from a tuberous 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-oval_.--Wet meadows and springs; common. April--June.--Flowers large, white.

Var. purpurea, Torr. Lower (4--6' high), and usually slightly p.u.b.escent; flowers rose-purple, appearing earlier.--Along streams in rich soil.

Western N. Y. to Md. and Wisc.

2. C. rotundiflia, Michx. (MOUNTAIN WATER-CRESS.) _Stems branching, weak or dec.u.mbent, making long runners; root fibrous_; 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. bellidiflia, L. _Dwarf_ (2--3' high), alpine, tufted; leaves ovate, entire, or sometimes with a blunt lateral tooth (4" long), on long petioles; pods 1' long, upright, linear; _style nearly 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; style short.--Wet places and bogs, Vt. to N. J., Wisc., and northward; rare. May. (Eu.)

[*][*][*] _Root mostly 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 cl.u.s.ter 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 spreading 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 acc.u.mbent or a little oblique.--Leaves seldom divided. Flowers white or purple. (Name from the country, _Arabia_. See _Linn. Phil. Bot._ -- 235.)

-- 1. ARABIS proper. _Seeds in one row in each cell, orbicular or nearly so, more or less wing-margined; cotyledons strictly acc.u.mbent._

[*] _Low, chiefly biennials, diffuse or spreading from the base._

1. A. Ludoviciana, Meyer. Nearly glabrous, often annual; leaves all pinnately parted into oblong or linear few-toothed or entire divisions, those of the lower leaves numerous; pedicels very short; flowers small, white; pods rather broadly linear, spreading, flat; seeds winged.--Open grounds, Va. to Mo., and southward.

[*][*] _Erect and simple leafy-stemmed biennials, with simple leaves, white or whitish flowers, narrow but flattened ascending or erect pods, and nearly wingless seeds._

2. A. patens, Sulliv. Downy with spreading hairs, erect (1--2 high); stem-leaves oblong-ovate, acutish, coa.r.s.ely toothed or the uppermost entire, partly clasping by the heart-shaped base; petals (bright white, 4" long) twice the length of the calyx; _pedicels slender, spreading; pods spreading or ascending, tipped with a distinct style_.--Penn. to central Ohio and southward; Minn. April, May.

3. A. hirsuta, Scop. Rough-hairy, sometimes smoothish, strictly erect (1--2 high); stem-leaves oblong or lanceolate, entire or toothed, partly clasping by a somewhat arrow-shaped or heart-shaped base; petals (greenish-white) small, but longer than the calyx; _pedicels and pods strictly upright; style scarcely any_; immature seeds somewhat 2-rowed.--Rocks, common, especially northward. May, June. (Eu.)

[*][*][*] _Erect and simple leafy-stemmed biennials (1--3 high), with small whitish flowers, recurved-spreading or pendulous flat pods (3--4'

long), and broadly winged seeds, their stalks adherent to the part.i.tion; root-leaves rarely lyrate._

4. A. laevigata, Poir. _Smooth_ and glaucous, upright; _stem-leaves partly clasping_ by the arrow-shaped base, lanceolate or linear, sparingly cut-toothed or entire; petals scarcely longer than the calyx; _pods long and narrow, recurved-spreading_ on ascending or merely spreading pedicels.--Rocky places, Maine to Minn. and southward. May.

5. A. Canadensis, L. (SICKLE-POD.) Stem upright, smooth above; _stem-leaves p.u.b.escent, pointed at both ends_, oblong-lanceolate, sessile, the lower toothed; petals twice the length of the calyx, oblong-linear; _pods very flat, scythe-shaped, hanging_ on rough-hairy pedicels (2" wide).--Woods and ravines; not rare, especially westward.

June--Aug.

-- 2. TURRTIS. _Seeds not so broad as the part.i.tion, in two more or less distinct rows in each cell, at least when young; strict and very leafy-stemmed biennials; cauline leaves partly clasping by a sagittate base. (Our species very glabrous, except the mostly hirsute base of the stem and the lower leaves.)_

6. A. perfoliata, Lam. (TOWER MUSTARD.) Tall (2--4 high), _glaucous_; stem-leaves oblong or ovate-lanceolate, entire; _petals yellowish-white, little longer than the calyx; pods very narrow_ (3' long) _and pedicels strictly erect_; seeds marginless; cotyledons often oblique.--Rocks and fields, N. Eng. to Minn. (rare), north and westward. (Eu.)

7. A. confnis, Watson. Scarcely glaucous, 1--3 high; p.u.b.escence below finely stellate; _stem-leaves lanceolate or oblong-linear_, entire (1--2' long), with narrow auricles, or the lowest spatulate and toothed; _petals white or rose-color, fully twice the length of the calyx_; pedicels and flat _pods loosely erect, or ascending, or even spreading_; seeds wing-margined, when mature little narrower than the part.i.tion. (A.

Drummondii, _Man._)--From the lower St. Lawrence to Minn., south to Conn., N. Y., and Ill.--Pods 2--3' long, or in a var. (T. brachycarpa, _Torr. & Gray_) only 1--2' long.

-- 3. PSEUDaRABIS. _Seeds oblong or elliptical, very small, wingless, in one row; cotyledons often more or less oblique. Biennial or perennial, branching from the base._

8. A. lyrata, L. Mostly glabrous, except the _lyrate-pinnatifid root-leaves_; stem-leaves scattered, spatulate or linear with a tapering base, sparingly toothed or entire; _petals white_, much longer than the yellowish calyx; pods long and slender, flat, ascending or spreading.--On rocks or sandy sh.o.r.es, New Eng. to Ky. along the mountains, Minn., and northward. April--July.--Usually biennial, but southward in the mountains decidedly perennial.

9. A. dentata, Torr. & Gray. Roughish p.u.b.escent, slender (1--2 high); _leaves oblong_, very obtuse, unequally and sharply toothed; those of the stem _numerous, half-clasping and eared_ at the base, of the root broader and tapering into a short petiole; petals (whitish) scarcely exceeding the calyx; _pods widely spreading, very slender, short-stalked; style scarcely any_.--N. Y. to Mich., Minn., and southward. May, June.

6. DRaBA, Dill. WHITLOW-GRa.s.s.

Pod oval, oblong, or even linear, flat; the valves plane or slightly convex; the part.i.tion broad. Seeds several or numerous, in 2 rows in each cell, marginless. Cotyledons acc.u.mbent. Filaments not toothed.--Low herbs with entire or toothed leaves, and white or yellow flowers; p.u.b.escence often stellate. (Name from d???, applied by Dioscorides to some cress; meaning unknown.)

-- 1. DRABae'A. _Petals not notched or cleft; perennial or biennial, leafy-stemmed, flowers white, pods twisted when ripe._

1. D. ramosissima, Desv. _Diffusely much branched_ and forming many radical tufts, perennial (5--8' high), p.u.b.escent; _leaves laciniate-toothed_, linear-lanceolate, the lower oblanceolate, racemes corymbosely-branched; _pods hairy_, oval-oblong or lanceolate (2--5"

long), on slender spreading pedicels, tipped with a _long style_.--Cliffs, Harper's Ferry, Natural Bridge, etc., Va., to Kentucky River, and southward. April, May.

2. D. incana, L. _h.o.a.ry-p.u.b.escent_, biennial or somewhat perennial, the radical tuft seldom branching; leaves oblanceolate or the cauline lanceolate to ovate, few-toothed or entire; _pods oblong to lanceolate, usually acute and straight, often p.u.b.escent_, on short erect pedicels; style very short or none.--Dry rocks, Willoughby Mountain, Vt.; also northward and far westward. (Eu.)

Var. arabisans, Watson. Caudex much branched; pod glabrous, ac.u.minate or acute, twisted, beaked with a longer distinct style. (D. arabisans, _Michx._)--N. Vt. to western N. Y. and the sh.o.r.es of the upper lakes.

-- 2. DRABeLLA. _Winter annuals; leafy stems short; flowers white (yellow in n. 5); style none. (Leaves oblong or obovate, hairy, sessile.)_

3. D. Caroliniana, Walt. Small (1--5' high); leaves obovate, entire; peduncles scape-like; petals usually twice the length of the calyx; _raceme short or corymbose in fruit_ (--1' long); _pods broadly linear, smooth_, much longer than the ascending pedicels.--Sandy and waste fields, E. Ma.s.s. to Minn., and southward. March--May.--Petals often wanting in the later racemes, especially in the var. MICRaNTHA, Gray, with minutely rough-hairy pods, which is found with the other, westward.

4. D. cuneiflia, Nutt. Leaves obovate, wedge-shaped, or the lowest spatulate, toothed; _raceme somewhat elongated in fruit_ (1--3'), at length equalling the naked peduncle; petals emarginate, much longer than the calyx; _pods oblong-linear, minutely hairy, longer than the horizontal pedicels_.--Gra.s.sy places, Ill. to E. Kan., and southward.

March, April.

5. D. brachycarpa, Nutt. Low (2--4' high), minutely p.u.b.escent; _stems leafy_ to the base of the dense at length elongated raceme; leaves narrowly oblong or the lowest ovate (2--4" long), few toothed or entire; flowers small; _pods smooth, narrowly oblong, acutish_ (2"

long), _about the length of the ascending or spreading pedicels_.--Dry hills, Ill., Ky., Va. (_A. H. Curtiss_), and southward. April.--Petals sometimes minute, sometimes none.

6. D. nemorsa, L. Leaves oblong or somewhat lanceolate, more or less toothed; _racemes elongated_ (4--8' long in fruit); petals emarginate, small; _pods elliptical-oblong, half the length of the horizontal or widely-spreading pedicels_, p.u.b.escent or smooth.--Fort Gratiot, Mich., N. Minn., and westward. (Eu.)

-- 3. ERoPHILA. _Petals 2-cleft. (Annual or biennial; flowers white.)_