Erodium cicutarium is a winter annual or biennial C3 herb (Ludwig et al. 2010), from a taproot, stems eventually 10-50 cm tall, weak, hairy, very short when first flowering, becoming taller and branched.
Leaves alternate, twice pinnately compound, elongate, widest above middle, leaflets to 2.5 cm, stalkless; overwintering leaves in a rosette.
Flowers pink-purple, petals to 0.8 cm long, slightly irregular, 2 upper petals slightly smaller than the 3 lower, sepals hairy, bristle-tipped; inflorescence of clusters of 2-12 flowers; blooms and fruits March-Nov.
Fruit dry, linear capsule to 4 cm long, splits into 5 segments, twisting open from base, hairy inside, each segment with a long, spirally twisting style with a seed attached at the base, style twists hygroscopically, drilling seed into soil. Seeds survive for 1-3 years in the soil (Manitoba Agriculture, Food and Rural Initiatives 2006; Global Invasive Species Database 2005).
Wetland status: UPL.
Frequency in NYC: Very infrequent.
Habitat: Open, sandy soil, an agricultural weed, also in lawns.