* Leaves strongly ribbed longitudinally.

P. major: leaves broadly ovate, with about seven prominent ribs converging at the base into the longish footstalk; spike long, slender, tapering, formed of small sessile flowers; capsule two-celled, with several seeds. - Roadsides and waste places. Pl June to August.

P. media: leaves ovate, nearly sessile, hoary, marked with 5-7 ribs; spike dense, cylindrical; capsule two-seeded. - Dry limestone pastures. Pl June to August.

P. lanceolata: leaves lanceolate, slightly hairy, with 3-5 ribs; spike ovoid or oblong; capsule with two seeds. - Ribwort. - Meadows, pastures, and waste places. Pl June, July.

** Leaves ivithout prominent ribs.

P. maritima: leaves narrow-linear, fleshy, entire, or slightly toothed; spike cylindrical; ovary two-celled. - Muddy salt-marshes. Fl. August, September.

P. Coronopus: leaves linear or linear-lanceolate, or pinna-tifid with linear segments, hairy; spikes cylindrical; ovary four-celled. - Star of the Earth. - Dry, stony or sandy places. Fl. June to August.