1. Arabis Virginica (L.) Trelease. Virginia Rock-Cress

Fig. 2069

Cardamine virginica L. Sp. Pl. 656. 1753. Cardamine ludoviciana Hook. Journ. Bot. 1: 191.

1834. A. ludoviciana Meyer, Ind. Sem. Petr. 9: 60. 1842.

Arabis virginica Trelease; Branner & Coville, Rep.

Geol. Surv. Ark. 1884: Part 4, 165. 1891. Planodes virginicum Greene, Leaflets 2: 221. 1912.

Annual or biennial, diffuse, glabrate, the stems ascending, 6'-12' high. Leaves oblong, narrow, deeply pinnatifid, 1 - 3' long, the lower petioled, the upper nearly sessile and sometimes reduced to lobed or entire bracts; pedicels spreading or ascending, 2" long in fruit; flowers very small, white; pods linear, ascending, 8"-12" long, about 1" broad; seeds in 1 row in each cell, nearly as broad as the pod, orbicular, wing-margined.

In open places, Virginia and Kentucky to Illinois, Kansas, Arkansas, south to Florida and Texas, west to southern and Lower California. March-May.

1 Arabis Virginica L Trelease Virginia Rock Cress 4111 Arabis Virginica L Trelease Virginia Rock Cress 412

2. Arabis LyrÓta L. Lyre-Leaved Rock-Cress

Fig. 2070

Arabis lyrata L. Sp. Pl. 665. 1753.

Cardamine spathulata Michx. Fl. Bor. Am. 2: 29. 1803.

Arabis lyrata occidentalis S. Wats.; Robinson in Gray & Wats. Syn. Fl. 1: Part 1, 159. 1895.

Tufted, perennial or biennial, erect, 4'-12' high, glabrous above, pubescent below, or sometimes glabrous, throughout. Basal leaves lyrate-pinnatifid, l'-2' long, spatulate or oblanceolate, pubescent or glabrous; stem-leaves entire or dentate, spatulate or linear, 1/2'-1' long; pedicels slender, ascending, 3"-4" long in flower, elongating in fruit; flowers pure white, 3"-4" broad; petals much exceeding the calyx; pods 9"-15" long, linear, ascending, less than 1" broad, their valves firm, nerved; style 1/2" long or less; seeds in 1 row, oblong, i" long, wingless.

Rocky and sandy places, Ontario to Connecticut, Virginia and Tennessee, west to Manitoba, Alaska, British Columbia and Missouri. Ascends to 2500 ft. in Virginia. Also in Japan. April-Sept.

3. Arabis Arenicola (Richards.) Gelert. Arctic Rock-Cress

Fig. 2071

Entrema arenicola Richards.; Hook. Fl. Bor. Am. 1: 67.

.1833. Sisymbrium humifusum J. Vahl, Fl. Dan. pl. 2297.

1840. A, humifusa S. Wats. Proc. Am. Acad. 25: 124. 1890. A. arenicola Gelert, Bot. Tidskr. 21: 270. 1898.

Perennial from a slender root, somewhat pubescent at least below, or entirely glabrous, the stems diffuse or ascending, slender, mostly simple, 3'-6' long. Leaves spatulate or oblong, nearly entire, 4"-8" long, 1"-2" wide, the lower petioled, the upper sessile; flowers purplish or white, about 3" broad; style very short; pods linear, flat, at length drooping, 8"-12" long, rather more than 1/2" wide, the valves very faintly nerved; seeds oblong, wingless, in 2 incomplete rows in each cell; cotyledons imperfectly accumbent.

Greenland and Labrador to Hudson Bay and the Northwest Territory. Summer.

3 Arabis Arenicola Richards Gelert Arctic Rock Cre 4133 Arabis Arenicola Richards Gelert Arctic Rock Cre 414