1. Leaves all cauline (opposite), 4–11 (–24) mm wide, on prostrate creeping stems; petals absent; flowers 4-merous.
1. Leaves all or mostly basal (no more than 2 cauline leaves, or several small alternate cauline bracts), often larger, the stems or scapes erect; petals present; flowers 5-merous.
2. Stamens 5.
2. Stamens 10.
3. Petals deeply pinnatisect; carpels in fruit spreading widely, exposing the seeds in a shallow flattish cup.
3. Petals entire; carpels in fruit not spreading but forming an elongate capsule or pair of follicles separate nearly to the base.
4. Leaf blades both lobed and irregularly toothed their entire length, strongly cordate, shorter than their petioles; carpels very unequal; inflorescence a simple raceme.
4. Leaf blades 3-toothed at apex, or at most with teeth or crenulations of equal size (or obscure), tapered at base (petiole usually shorter than the blade, obscure, or none); carpels equal; inflorescence branched.
5. Basal leaves minutely crenulate, nearly entire, or with obtuse green teeth; petals not dotted; flowering stem at most with 1–2 small bracts between the inflorescence and basal leaves.
5. Basal leaves with cartilaginous sharp teeth (either 3 spines at the end, or regular flat teeth with lime encrustations); petals usually dotted with red or purplish; flowering stem with several bracts or small leaves.