This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Annual or perennial herbs, often with large rosettes of leaves, glabrous or hairy. Radical leaves spathulate, cauline sessile. Flowers white, more rarely purple. Pod linear, compressed, keeled, not elastic; seeds compressed in 1 or 2 series. Species numerous, chiefly from the temperate and arctic regions of the northern hemisphere. The name is from Arabia, the native country of some species.
1. A. albida, syn. A. Caucdsica. - Very common in old gardens, and a very hardy Spring flowering plant. It grows in patches with slender running stems and rosettes of pale green spathulate toothed leaves clothed with greyish hairs. Flowers pure white, in elongating racemes on leafy erect stems. There is a very pretty variegated variety. Mediterranean region, etc. A. alplna is probably an alpine form of this species.
2. A. blepharophylla. - Similar to the preceding in habit and foliage, but with rosy-purple flowers. From California, but not yet very widely spread in gardens. June.
3. A. lucida. - This species has dense rosettes of glabrous shining sessile spathulate leaves and very small white flowers.
The variegated form is very beautiful, and now very extensively used for edging. A native of Hungary, flowering in the month of June.