S. mèdia, Smith. (Common Chickweed.) Annual or nearly so; lower leaves on hairy petioles, petals shorter than the calyx, 2-parted, stamens 3–10.—Everywhere in damp grounds. (Nat. from Eu.)
1. S. pùbera, Michx. (Great Chickweed.) Root perennial; leaves all sessile; petals longer than the calyx, deeply 2-cleft; stamens 10.—Shaded rocks, Penn. to Ind., and southward. May.
[*][*] Stems erect or spreading; wholly glabrous perennials, with sessile and narrow or small leaves; stamens usually 10, perigynous.
[+] Scaly-bracted; petals 2-parted, equalling or surpassing the calyx.
2. S. longifòlia, Muhl. (Long-leaved Stitchwort.) Stem erect, weak, often with rough angles (8–18´ high); leaves linear, acutish at both ends, spreading; cymes naked and at length lateral, peduncled, many-flowered, the slender pedicels spreading; petals 2-parted, longer than the calyx; seeds smooth.—Grassy places; common, especially northward. June, July. (Eu.)
3. S. lóngipes, Goldie. (Long-stalked S.) Shining or somewhat glaucous, very smooth; leaves ascending, lanceolate or linear-lanceolate, acute, broadest at the base, rather rigid; cyme terminal, few-flowered, the long pedicels strictly erect; petals longer than the calyx; seeds smooth.—Maine to Minn., rare; common farther north. (Eu.)
S. gramínea, L. Resembling the last; leaves linear-lanceolate, broadest above the base; pedicels widely spreading; seeds strongly but minutely rugose.—Becoming rather frequent. (Int. from Eu.)
4. S. uliginòsa, Murr. (Swamp S.) Stems weak, decumbent or diffuse, at length prolonged, leaving the naked and usually sessile cymes lateral; leaves lanceolate or oblong, veiny; petals and ripe pods as long as the calyx; seeds roughened.—Swamps and rills, Md. to N. Eng., and northward; rare. (Eu.)
[+][+] Flowers terminal or in the forks of the stem or of leafy branches; bracts foliaceous; petals 2-parted, small or often none; styles 3–4; pod longer than the calyx.
5. S. crassifòlia, Ehrh. Stems diffuse or erect, flaccid; leaves rather fleshy, varying from linear-lanceolate to oblong; petals longer than the calyx, or wanting; seeds rugose-roughened.—Springy places, eastern Ky. (Short), Ringwood, Ill. (Vasey), and northward. April–June. (Eu.)