8. Arabis Glābra (L.) Bernh. Tower Mustard Or Cress

Fig. 2076

Turritis glabra L. Sp. Pl. 666. 1753.

Arabis glabra Bernh. Verz. Syst. Erf. 195. 1800.

Arabis perfoliata Lam. Encycl. 1: 219. 1783.

Biennial, erect, glabrous and decidedly glaucous above, pubescent at the base, nearly simple, 2°-4° high. Basal leaves petioled, 2'-10' long, oblanceolate or oblong, dentate or sometimes lyrate, hairy with simple pubescence, or with hairs attached by the middle; stem-leaves sessile, with a sagittate base, glabrous, entire or the lower sparingly dentate, 2'-6' long, lanceolate or oblong, acutish; pedicels 2"-6" long, erect; flowers yellowish-white, 2" broad; petals slightly exceeding the calyx; pods narrowly linear, 2'-3' long, 1/2" wide, strictly erect and appressed; seeds marginless; style none.

In fields and rocky places, New Brunswick to southern New York and Pennsylvania, west to the Pacific Coast. Appears in some places as if not indigenous. Also in Europe and Asia. May-Aug.

9. Arabis Laevigāta (Muhl.) Poir. Smooth Rock-Cress

Fig. 2077

Turritis laevigata Muhl.; Willd. Sp. Pl. 3: 543. 1801. A. laevigata Poir. in Lam. Encycl. Suppl. 1: 411. 1810. Arabis laevigata Burkii Porter, Bull. Torr. Club 17:

15. 1890. A. laevigata laciniata T. & G. Fl. N. A. 1: 82. 1838.

Glaucous, entirely glabrous, 1°-3° high, nearly simple. Basal leaves petioled, spatulate or obovate, sharply and deeply dentate, or sometimes laciniate, 2'-3' long; stem-leaves sessile, lanceolate, or the upper linear, acute, entire or dentate, usually clasping by an auricled or sagittate base; pedicels ascending or spreading, 4"-5" long in fruit; flowers greenish white, 2"-3" high; petals nearly twice the length of the calyx or less; pods 3'-4' long, 1" wide, recurved-spreading; seeds in 1 row, oblong, broadly winged; style almost none.

In rocky woods, Quebec to Ontario, South Dakota, Georgia and Arkansas. April-June.

Arabis serķtina Steele, found at Millboro, Virginia, differs in being widely branched, its narrower leaves not clasping, its flowers smaller, appearing in August.

Arabis viridis Harger, a recently proposed New England species, differs in being green, more leafy, the pedicels erect in flower, the petals longer.

9 Arabis Laevig Ta Muhl Poir Smooth Rock Cress 4199 Arabis Laevig Ta Muhl Poir Smooth Rock Cress 420

10. Arabis Canadénsis L. Sickle-Pod

Fig. 2078

Arabis canadensis L. Sp. Pl. 665. 1753.

Stem nearly simple, 1°-3° high, pubescent below, glabrous above. Basal leaves narrowed into a petiole, blunt but sometimes acutish, dentate or lyrately lobed, 3'-7' long; stem-leaves sessile, not clasping, lanceolate or oblong, narrowed at each end, toothed, or the upper entire, pubescent; pedicels hairy, ascending and 2"-4" long in flower, spreading or recurved and 4"-6" long in fruit; flowers greenish-white, 2"-3" long; petals twice as long as the calyx; pods 2'-3 1/2' long, 1 1/2"-2" broad, scythe-shaped, pendulous; seeds in 1 row in each cell, oblong, wing-margined; style almost none.

In woods, Maine, Vermont and Ontario to Georgia, west to Minnesota, Kansas, Arkansas and Texas. Ascends to 4200 ft. in North Carolina. June-Aug.