Sepals 4 or 5. Petals 4 or 5, undivided, or often none. Stamens as many as the sepals, rarely twice as many. Styles as many as the sepals and alternate with them. Pod many-seeded, 4--5-valved to the base; valves opposite the sepals.--Little, matted herbs, with thread-like or awl-shaped leaves, no stipules, and small flowers terminating the stems or branches; in summer. (Name from _sagina_, fattening; previously applied to the spurry.)
[*] _Parts of the flower in fours, rarely with some few in fives._
1. S. procúmbens, L. Annual or perennial, _depressed or spreading_ on the ground, glabrous; leaves linear-thread-shaped; _apex of the peduncle often hooked_ soon after flowering; _petals shorter than the_ broadly ovate obtuse _sepals_, sometimes none.--Springy places and damp rocks, coast of Maine to Penn. (Eu.)
2. S. apétala, L. _Annual, erect_ or ascending; leaves ciliate at base or glabrous; _petals none_ or very small; _peduncles always erect_.--Dry soil, Mass. to Penn.; scarce, seemingly native? (Eu.)
[*][*] _Parts of the flower in fives, the stamens not rarely 10._
3. S. decúmbens, Torr. & Gray. Annual, ascending; the peduncles and calyx with the margins of the upper leaves _at first glandular-pubescent_; leaves short, often bristly-tipped, not fascicled in the axils; peduncles slender; _petals equalling or shorter than the calyx_; pod oblong-ovate, nearly twice longer than the acutish sepals. (S. subulata, _Man._, not _Wimm._)--E. Mass., to Ill., Mo., and southward.--Var. SMÍTHII, a slender form, _apetalous_, at least in the later flowers.--Near Philadelphia, in waste ground, and in sandy fields at Somers' Point, N. J., _C. E. Smith._ Seeds minutely roughened.
4. S. nodòsa, Fenzl. Perennial, tufted, glabrous, or glandular above; stems ascending (3--5´ high); lower leaves thread-form, the upper short and awl-shaped, with minute ones _fascicled in their axils so that the branchlets appear knotty, petals much longer than the calyx._--Wet sandy soil, along the coast of Maine and N. H., also Lake Superior, and northward. (Eu.)
Sepals 5. Petals 5, entire. Stamens 2--10. Styles and valves of the many-seeded pod 3, very rarely 5, when the valves alternate with the sepals! Embryo not coiled into a complete ring.--Low herbs, mostly on or near the seacoast, with filiform or linear somewhat fleshy opposite leaves, and smaller ones often clustered in the axils; stipules scaly-membranaceous; flowering all summer. (Named probably for the city so called.)--Genus also known as TISSA, Adans., SPERGULARIA, Presl., and LEPIGONUM, Wahlb. The species are very variously understood by European botanists, and are much confused, as well as the synonymy. Our forms are annual, or at the most biennial.