[Turritis L. Sp. Pl. 666. 1753.]

Annual, biennial or perennial, glabrous or pubescent herbs, with entire lobed or pinnatifid leaves and white or purple flowers. Siliques linear, elongated, flat; valves smooth, mostly 1-nerved, not elastically dehiscent at maturity. Stigma 2-lobed or nearly entire. Seeds in 1 or 2 rows in each cell, flattened, winged, margined or marginless; cotyledons accumbent. [Name from Arabia.]

A genus of about 120 species, mainly natives of the northern hemisphere. In addition to the following, about 35 other species occur in the northern and western parts of the continent. Type species: Arabis alpina L. Called also Wall-cress.

Seeds in 1 row or 2 incomplete rows in each cavity of the pod.

Basal leaves pinnatifid; pods ascending.

Seeds large, orbicular, wing-margined; stem-leaves pinnatifid.

1.

A. virginica.

Seeds minute, oblong, wingless; stem-leaves entire, or dentate.

2.

A. lyrata.

Leaves small, mostly entire; pods drooping; seeds oblong, wingless; arctic.

3.

A. arenicola.

Basal leaves merely dentate or lyrate.

Seeds minute, oblong, wingless.

4.

A. dentata.

Seeds larger, oblong, winged or margined.

Pods curved upward, nearly 1" broad.

5.

A. alpina.

Pods nearly erect, 1/2" broad.

Flowers white, 4" broad; pods not appressed; style 1/2" long.

6.

A. patens.

Flowers white or greenish-white, 2"-3" broad; pods appressed; style none.

Seeds wing-margined; plant not glaucous.

7.

A. hirsuta.

Seeds wingless: plant glaucous.

8.

A. glabra.

Pods recurved-spreading.

Plant glabrous throughout.

9.

A. laevigata.

Leaves and lower part of stem hairy.

10.

A. canadensis.

Seeds in 2 distinct rows in each cavity of the pod.

Pods spreading, erect or ascending; seeds winged.

Pods erect; basal leaves glabrous or nearly so.

11.

A. Drummondii.

Pods spreading; basal leaves stellate-pubescent.

12.

A. brachycarpa.

Pods reflexed; seeds winged.

Basal and lower leaves loosely long-pubescent; pods blunt.

13.

A. Holboellii.

Basal and lower leaves finely stellate-pubescent; pods acute.

14.

A. Collinsii.