Annuals; (littoral or aquatic); scapose; glabrous throughout. Stems erect, unbranched. Leaves (persistent); basal; rosulate; sessile; blade margins entire; cauline absent. Racemes (lax or somewhat congested), slightly or considerably elongated in fruit. Fruiting pedicels usually ascending, rarely divaricate, divaricate-ascending, or suberect, slender or stout. Flowers: sepals (sometimes persistent), ascending to erect, ovate -oblong, lateral pair not saccate basally; petals (rarely absent), white, narrowly oblanceolate to lingulate, (slightly exceeding sepals), claw undifferentiated from blade, apex obtuse; stamens subequal; filaments not dilated basally; anthers ovate; nectar glands confluent, subtending bases of stamens. Fruits silicles, shortly stipitate, obovoid to ellipsoid [oblong], smooth, terete or slightly inflated; valves each not veined; replum rounded; septum complete; ovules 4-18 per ovary; style absent; stigma capitate. Seeds biseriate, slightly compressed, not winged, oblong; seed coat not mucilaginous when wetted; cotyledons incumbent. x = 14, 15.