20. Holosteum Linnaeus, Sp. Pl. 1: 88. 1753. Gen. Pl. ed. 5, 39. 1754.
Jagged chickweed [Greek holos, whole or all, and osteon, bone, humorous allusion to frailty of the plant]
Richard K. Rabeler, Ronald L. Hartman
Herbs, annual or winter-annual. Taproots slender. Stems ascending to erect, simple or branched, terete. Leaves forming basal rosette, connate proximally into sheath, petiolate (proximal leaves) or sessile (cauline leaves); blade 1-veined, oblanceolate to spatulate (proximal leaves) or elliptic to ovate (cauline leaves), somewhat succulent, apex acute. Inflorescences terminal, umbellate cymes, sometimes not yet developed in young individuals, then with 2-4 bracts and often buds at base of pedicel; bracts clustered, foliaceous with scarious margins to entirely scarious. Pedicels reflexed after flowering, erect in fruit. Flowers bisexual or occasionally unisexual and pistillate; perianth and androecium hypogynous; sepals 5, distinct, green, lanceolate to ovate, 2.5-4.5 mm, herbaceous, margins white, scarious, apex acute to obtuse, not hooded; petals 5, white to pink, clawed, blade apex jagged but not 2-fid; nectaries not apparent; stamens 3-5, arising from base of ovary; filaments distinct nearly to base; staminodes absent; styles 3(-5), clavate to filiform, 0.5-1.5 mm, glabrous proximally; stigmas 3(-5), subterminal to linear along adaxial surface of styles, minutely papillate (50×). Capsules ovoid to cylindric, opening by 6 (rarely 8 or 10) revolute teeth; carpophore absent. Seeds 35-60, orange to brown, oblong, shield-shaped, dorsiventrally compressed, papillate, marginal wing absent, appendage absent; embryo central, straight. x = 10.
Species 3-4 (1 in the flora): introduced; Europe (e Mediterranean region), c, sw Asia, Africa (Mediterranean region, s to Ethiopia); introduced in South America (Argentina), w Europe, Africa (Republic of South Africa).
SELECTED REFERENCE
Shinners, L. H. 1965. Holosteum umbellatum (Caryophyllaceae) in the United States: Population explosion and fractionated suicide. Sida 2: 119-128.
