Spergularia

Herbs, annual or strongly perennial with branched, woody caudex. Taproots filiform to stout. Stems erect to sprawling, simple to freely branching distally or throughout, terete, sometimes woody. Leaves opposite, axillary clusters of leaves often present, distinct, sessile; stipules 2 per node, white to tan, lanceolate and acuminate to widely triangular, margins entire, apex entire to variously split; blade 1-veined, threadlike to linear, mostly succulent, apex acute to acuminate. Inflorescences terminal cymes, branching symmetrically or to 1 side (monochasium), simple to 8+-compound or sometimes flowers solitary and axillary; bracts usually paired or sometimes single, smaller, foliaceous, distalmost sometimes with scarious margins. Pedicels ascending to erect, divergently spreading, reflexed, or arching downward in fruit. Flowers: perianth and androecium hypogynous, briefly perigynous; hypanthium dish- or cup-shaped, not abruptly expanded distally; sepals connate in proximal 1/5, green, lanceolate to ovate, 0.9–8 mm, herbaceous, margins scarious, apex acute to obtuse; petals 5, white to pink, blade apex entire; nectaries as lateral expansion of bases of filaments opposite sepals; stamens 1–10, arising from rim of hypanthium; filaments distinct; styles 3, distinct or nearly so, filiform, 0.2–3 mm, glabrous proximally; stigmas 3, linear along adaxial surface of styles, obscurely papillate (30×). Capsules ovoid, opening by 3 spreading valves with recurved tips; carpophore absent. Seeds 30–150+, light to dark brown, reddish brown, or black, circular to angular, plump or laterally compressed, smooth to variously sculptured to papillate, complete or partial, membranous, laciniate, marginal wing often present, appendage absent. x = 9.

Distribution

Coastal and saline areas, w North America (including Mexico), Central America, w South America, Europe (Mediterranean region), Africa (Mediterranean region).

Discussion

Species ca. 60 (11 in the flora).

We follow the species order of R. P. Rossbach (1940). While there have been attempts to define species groups, and sections have been described, all such efforts focus only on European-Mediterranean taxa, ignoring the many taxa endemic to South America. Likewise, the major breaks in the key to species follow Rossbach’s revision. Attempts to construct a key independent of habit were not successful; Spergularia is a difficult genus in which emphasis on seed characters appears necessary.

Spergularia is included in the first list of nomina genericorum conservanda published in 1905, conserved against Buda and Tissa. This action most likely occurred as a result of bickering between J. Britten and N. L. Britton in 1888–1890 about usage of the genera that Adanson had erected for Spergularia species with ten and five stamens respectively; see J. Britten (1890) for a summary of the arguments.

Selected References

Rossbach, R. P. 1940. Spergularia in North and South America. Rhodora 42: 57–83, 105–143, 158–193, 203–213.

Lower Taxa

Spergularia atrosperma, Spergularia bocconi, Spergularia canadensis, Spergularia diandra, Spergularia echinosperma, Spergularia macrotheca, Spergularia media, Spergularia platensis, Spergularia rubra, Spergularia salina, Spergularia villosa

Key

1	Plants strongly perennial, base woody; stamens 7-10	> 2
1	Plants annual or short-lived perennial, base not woody; stamens 1-10	> 3
2	Seeds 0.4-0.5 mm; sepal lobes 2.5-4 mm, to 5 mm in fruit; styles 0.4-0.6 mm	Spergularia villosa
2	Seeds (0.6-)0.7-1.2 mm; sepal lobes 4.5-7 mm, to 8 mm in fruit; styles 0.6-3 mm	Spergularia macrotheca
3	Seeds black, not papillate	> 4
3	Seeds light to dark brown or reddish brown, if nearly black, seeds covered with gland-tipped papillae	> 5
4	Seeds 0.6-0.8 mm, broadly ovate, often with iridescent tinge, sculpturing of parallel, wavy lines; stipules 1-2.5 mm	Spergularia atrosperma
4	Seeds 0.4-0.6 mm, pyriform, often with silvery, not iridescent, tinge, sculpturing of low, elongate tubercles; stipules 1.5-2 mm	Spergularia diandra
5	Stamens 6-10	> 6
5	Stamens 1-5	> 8
6	Seeds 0.8-1.1 mm, ± smooth, not papillate, usually winged; capsules usually (4.5-)5.5-8 mm; plants stout; main stems usually 1-4 mm diam. proximally; leaf blades markedly fleshy	Spergularia media
6	Seeds 0.4-0.6 mm, roughened or variously sculptured, papillate, not winged; capsules 2.8-5.4 mm; plants ± delicate; main stems usually 0.3-1 mm diam. proximally; leaf blades scarcely to somewhat fleshy	> 7
7	Axillary leaves 2-4+ per cluster, blade scarcely fleshy; seeds reddish brown to dark brown; stipules lanceolate, apex ± long-acuminate, shiny white, conspicuous	Spergularia rubra
7	Axillary leaves absent or 1-2 per cluster, blade at least moderately fleshy; seeds light brown; stipules mostly deltate, apex acute to short-acuminate, dull white to tan, usually inconspicuous	Spergularia bocconi
8	Seeds 0.9-1.4 mm; capsules (1.2-)1.5-2 times as long as sepals.	Spergularia canadensis
8	Seeds 0.3-0.7(-0.8) mm; capsules 0.9-1.5 times as long as sepals	> 9
9	Plants glabrous; capsules 1.4-2.6 mm; sepal lobes 0.9-1.6 mm, to 2 mm in fruit; seeds 0.3-0.4 mm	Spergularia platensis
9	Plants with stalked glands in inflorescence or throughout; capsules 2.8-6.4 mm; sepals lobes 1.8-4.5 mm, to 4.8 mm in fruit; seeds 0.5-0.7(-0.8) mm	> 10
10	Seeds dull, not silver tinged, ± smooth; stipules longer than wide; styles 0.4-0.7 mm	Spergularia salina
10	Seeds shiny, silver tinged, slightly roughened; stipules shorter than wide; styles 0.3-0.4 mm	Spergularia echinosperma