1Annual or biennial herbs with slender stock and roots; without non-flowering shoots.
1'Perennials with stout stock and root; non-flowering shoots usually present at flowering time.
2Bracteoles as long as calyx or longer; leaves narrowly elliptic to elliptic, at least some leaves (lower) obtuse or subobtuse.
2'Bracteoles much shorter than calyx; leaves narrowly elliptic to linear, all leaves acute or acuminate.
3Leaves linear-narrowly elliptic, flat, 3-6 mm broad; petal blades narrow, not touching below, divided more than halfway down into very narrow, hair-like lobes.
3'Leaves linear, 1-3 mm broad, petal blades divided one third to halfway down into narrow but not thread-like lobes.
4Whole plant not more than 35 cm tall; leaf pairs above the rosette 1-4, leaves about 1 mm broad.
4'Whole plant 50-80 cm tall; leaf pairs above the rosette 5-7; leaves 2-3 mm broad, nearly flat.