Sp. Pl. 1: 128. 1753.
Gen. Pl. ed. 5, 62. 1754.
Herbs, annual, winter-annual, or perennial, often cespitose or matted. Taproots slender. Stems ascending, decumbent, or procumbent, simple or branched, terete to slightly angular. Leaves: basal and secondary rosettes present in perennial species, usually connate proximally, sometimes forming conspicuous, scarious cup, sessile, with or without axillary fascicles of leaves; blade 1-veined, linear to subulate, succulent or not, apex acute to mucronate or apiculate (or long-aristate in S. subulata). Inflorescences terminal or axillary cymes, or flowers solitary; bracts paired, foliaceous. Pedicels erect or spreading. Flowers: perianth and androecium hypogynous; sepals 4 or 5, distinct, green or sometimes purple (in S. nivalis and S. decumbens), lanceolate to elliptic or orbiculate, 1–5.5 mm, herbaceous, margins white or purple, scarious, apex obtuse or rounded to somewhat acute, frequently hood-shaped in bud; petals 4 or 5, sometimes absent (frequently absent or soon dropping in annual species), white, claw absent or minute, blade apex entire; nectaries at base of filaments opposite sepals; stamens 4, 5, 8, or 10, arising from base of ovary; filaments distinct; staminodes absent; styles 4 or 5, clavate to filiform, 0.5–1.5 mm, glabrous proximally; stigmas 4 or 5, subterminal to linear along adaxial surface of styles, minutely papillate (30×). Capsules globose to ovoid, opening by 4 or 5 valves, sutures running to base, but in some species dehiscing only ca. 1/4–1/2 capsule length; carpophore absent. Seeds ca. 125, light tan to dark or reddish brown, obliquely triangular with abaxial groove, or reniform to nearly globose without abaxial groove (except S. nodosa, which is intermediate), laterally compressed or plump, smooth to tuberculate, marginal wing absent, appendage absent. x = 6, 7, 11.
Chiefly cold-temperate Northern Hemisphere, also on some tropical mountains.
Species 15–20 (10 in the flora).
|1||Petals nearly 2 times sepals, 3-4.5 mm; distal cauline leaves and lateral branches usually with axillary fascicles of minute, succulent leaves, giving knotted appearance||Sagina nodosa|
|1||Petals shorter than, equaling, or barely longer than sepals, 0.8-3 mm, or absent; cauline leaves and procumbent stems sometimes with axillary fascicles resembling cauline leaves, not minute, succulent||> 2|
|2||Flowers 5-merous; leaf blades fleshy; seeds reniform or nearly globose, plump, abaxial groove absent||> 3|
|2||Flowers 4-5-merous; leaf blades not fleshy, or if slightly fleshy, then flowers predominantly 4-merous; seeds obliquely triangular, with abaxial groove||> 5|
|3||Calyx bases and distal portion of pedicels glabrous||Sagina maxima|
|3||Calyx bases and distal portion of pedicels glandular-pubescent||> 4|
|4||Seeds reddish brown, smooth or slightly pebbled||Sagina maxima|
|4||Seeds dark brown, usually distinctly tuberculate or strongly pebbled||Sagina japonica|
|5||Plants annual; stems filiform; distal cauline leaf blades subulate, becoming shorter distally||> 6|
|5||Plants perennial; stems not filiform; distal cauline leaf blades linear, linear-subulate, or, if subulate, then plants cespitose||> 7|
|6||Flowers 5-merous (rarely 4-merous, and then apetalous); leaf blade bases never ciliate; capsules longer than sepals||Sagina decumbens|
|6||Flowers 4-merous, rarely 4- and 5-merous; leaf blade bases distinctly ciliate, especially of distal cauline leaves; capsules equaling or barely longer than sepals||Sagina apetala|
|7||Plants cespitose, forming low cushions; cauline leaf blades subulate; hyaline sepal margins purple||> 8|
|7||Plants with stems ascending, spreading, procumbent, or mat-forming (sometimes cespitose in alpine sites); leaf blades linear; hyaline sepal margins white||> 9|
|8||Flowers 4-merous, sometimes accompanied by 5-merous flowers; petals shorter than or equaling sepals, 1.5-2 mm; primary basal rosette of fleshy, subulate leaves present, secondary rosettes absent||Sagina nivalis|
|8||Flowers 5-merous, sometimes accompanied by 4-merous flowers; petals longer than or rarely equaling sepals, 2.5-3 mm; primary basal rosette of leaves absent, secondary rosettes of linear leaves often present||Sagina caespitosa|
|9||Flowers 4-merous, sometimes accompanied by 5-merous flowers; petals 0.8-1 mm, sometimes absent; sepals divergent at time of capsule dehiscence||Sagina procumbens|
|9||Flowers 5-merous; petals (1-)1.5-2 mm; sepals appressed to loosely appressed at time of capsule dehiscence||> 10|
|10||Plants glabrous; cauline leaf blade apices apiculate; connate leaf bases not forming conspicuous cup||Sagina saginoides|
|10||Plants with leaves, stems, pedicels, and calyx bases glandular-pubescent; cauline leaf blade apices aristate, aristae equaling or exceeding leaf width; connate leaf bases forming conspicuous, scarious cup||Sagina subulata|