Scleranthus annuus |
Scleranthus |
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annual knawel, German knotgrass, scléranthe annuel |
German knotgrass, knawel, scléranthe |
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Habit | Herbs, annual, biennial, or perennial. | |||||
Taproots | slender. |
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Stems | erect to prostrate, branched, terete. |
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Leaves | connate proximally, sessile; blade 1-veined, subulate to linear, not succulent, apex acute or obtuse. |
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Inflorescences | terminal or axillary, lax to dense cymes; bracts paired, foliaceous. |
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Flowers | sessile to subsessile; perianth and androecium perigynous; hypanthium urceolate, abruptly expanded distally; sepals 5, distinct, greenish, lanceolate to awl-shaped, 1.5–4 mm, herbaceous, margins whitish, scarious, apex acute to blunt or obtuse; petals absent; nectariferous disc at base of stamens; stamens 2–10, arising from hypanthium rim; filaments distinct; staminodes absent or 5–8, arising from hypanthium rim, filiform; styles 2, capitate, 0.8–1 mm, glabrous proximally; stigmas 2, terminal, minutely papillate (50x). |
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Seeds | 1, yellowish, globose, not compressed, smooth, marginal wing absent, appendage absent. |
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Utricles | ovoid, enclosed in persistent, indurate, shallowly or strongly furrowed, sepal-crowned hypanthium and falling with it, the whole constituting the indehiscent “fruit”; carpophore present. |
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x | = 11 [12]. |
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Scleranthus annuus |
Scleranthus |
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Distribution |
AL; AR; CA; CT; DC; DE; FL; GA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; NE; NH; NJ; NY; OH; OK; OR; PA; RI; SC; TN; VA; VT; WA; WI; WV; AB; BC; NB; NF; NS; ON; PE; QC; SK; Europe; w Asia; n Africa
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temperate Europe (including Mediterranean region); Asia; Africa; Australia; widely naturalized elsewhere [Introduced in North America] |
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Discussion | Subspecies 8 (1 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Species ca. 10 (2 in the flora). In spite of their small size, most Scleranthus flowers secrete nectar and are visited by insects, including small flies and ants. Pollination in species within the flora area varies from chiefly protandrous outcrossing (S. perennis) to chiefly autogamous (S. annuus). L. Svensson (1988) reported that these two species hybridize regularly in Europe, producing flowers with ten reduced, sterile stamens. The common name “knawel” apparently refers to the glomerules of flowers (German Knäuel). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 5, p. 150. | FNA vol. 5, p. 149. | ||||
Parent taxa | Caryophyllaceae > subfam. Alsinoideae > Scleranthus | Caryophyllaceae > subfam. Alsinoideae | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Name authority | Linnaeus: Sp. Pl. 1: 406. (1753) | Linnaeus: Sp. Pl. 1: 406. 1753 (as Schleranthus): Gen. Pl. ed. 5, 190. (1754) | ||||
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