Spergula

Herbs, annual or winter annual. Taproots slender to ± stout, especially proximally. Stems spreading or ascending to erect, simple or branched, terete to somewhat angular. Leaves opposite but appearing whorled, as 8–15 per axillary cluster, 2 clusters per node, connate proximally by often-prominent ridge from which stipules arise, sessile; stipules 4 per node, white, ovate to triangular, margins entire but splitting variously with age, apex obtuse to acuminate; blade 1-veined, linear or filiform, sometimes succulent, apex blunt to apiculate. Inflorescences terminal, open to diffuse cymes; bracts paired, minute. Pedicels erect to ascending, spreading or usually reflexed and sometimes secund in fruit. Flowers usually bisexual, sometimes pistillate by stamen abortion; perianth and androecium briefly perigynous; hypanthium dish- or cup-shaped, not abruptly expanded distally; sepals distinct, silvery, elliptic to nearly ovate, 2.5–5 mm, herbaceous, margins scarious, apex acute to obtuse; petals 5, white, blade apex entire; nectaries at adaxial base of broader filaments opposite sepals; stamens 5 and opposite sepals, or 10 and arising from distally tapered rim of hypanthium; filaments distinct; styles 5, distinct, filiform, 0.4–0.6 mm, glabrous proximally; stigmas 5, linear along adaxial surface of styles, obscurely papillate (30×). Capsules ovoid, opening by 5 spreading to somewhat recurved valves; carpophore absent. Seeds 5–25, blackish, circular, subglobose or lenticular and laterally compressed, nearly smooth or finely papillate, membranous, entire marginal wing often present, appendage absent; embryo peripheral, annular to spirally curved. x = 9.

Distribution

Eurasia (esp. Mediterranean region, Europe).

Discussion

Species 5 (3 in the flora).

Spergula arvensis is the only species of the genus that has been introduced extensively outside of Eurasia.

Selected References

None.

Lower Taxa

Spergula arvensis, Spergula morisonii, Spergula pentandra

Key

1	Leaf blades usually appearing terete, 1.5-3(-5) cm, margins often revolute, forming abaxial channel; seeds subglobose, sometimes with keel or wing ± 0.1 mm wide	Spergula arvensis
1	Leaf blades usually flat, 0.3-1.5(-2) cm, usually not channeled abaxially; seeds lenticular, laterally compressed, wings 0.2-0.6 mm wide	> 2
2	Seed wings light brown to brownish black, 0.2-0.3 mm wide; stamens usually 10	Spergula morisonii
2	Seed wings white or sometimes slightly tannish, 0.4-0.6 mm wide; stamens usually 5	Spergula pentandra