Stellaria obtusa |
Stellaria americana |
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blunt-sepal starwort, obtuse starwort, Rocky Mountain chickweed, Rocky Mountain starwort |
American chickweed, American starwort |
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Habit | Plants perennial, creeping, often matted but not forming cushions, rhizomatous. | Plants perennial, forming loose, prostrate mats, from rhizomatous rootstocks. |
Stems | prostrate, branched, 4-sided, 3–23 cm, internodes equaling or longer than leaves, glabrous, rarely pilose. |
spreading, branched, very leafy, 4-angled, 10–20 cm, short glandular-puberulent on internodes. |
Leaves | sessile or short-petiolate; blade broadly ovate to elliptic, 0.2–1.2 cm × 0.9–7 mm, base round or cuneate, margins entire, apex acute, shiny, glabrous or ciliate near base. |
sessile; blade ovate to ovate-lanceolate, widest at or above middle, 8–30 × 2–13 mm, base round to cuneate, margins not scarious, apex usually obtuse, viscid. |
Inflorescences | with flowers solitary, axillary; bracts absent. |
terminal, 1–5-flowered, very leafy cymes; bracts foliaceous. |
Pedicels | spreading, 3–12 mm, glabrous. |
ca. 10 mm in flower, elongating, recurved, and tortuous in fruit, glandular-pubescent, pushing capsule into substrate. |
Flowers | 1.5–2 mm diam.; sepals 4–5, veins obscure, midrib sometimes apparent, ± ovate, 1.5–3.5 mm, margins narrow, scarious, apex ± obtuse, glabrous; petals absent; stamens 10 or fewer; styles 3(–4), curled, shorter than 0.5 mm. |
5–10 mm; sepals 5, obscurely veined, ovate-obtuse, 3–5 mm, margins narrow, scarious, glandular-pubescent; petals 5, 4–6 mm; stamens 5; styles 3, ascending, equaling petals. |
Capsules | green to pale straw colored, translucent, globose to broadly ovoid, 2.3–3.5 mm, 1.9–2 times as long as sepals, apex obtuse, opening by 6 valves; carpophore absent. |
green to straw colored, broadly ovoid to globose, 5–6 mm, apex obtuse, tardily dehiscent with 3 valves; carpophore absent. |
Seeds | grayish black, broadly elliptic, 0.5–0.7 mm diam., finely reticulate. |
3–6, rusty brown, ± ovate, ca. 2.5 mm diam., finely tuberculate. |
2n | = 26, 52, ca. 65, ca. 78. |
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Stellaria obtusa |
Stellaria americana |
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Phenology | Flowering late spring–summer. | Flowering late Jul–Aug. |
Habitat | Moist areas in woods, shaded edges of creeks, talus slopes | Rocky slopes, talus |
Elevation | 300-3400 m (1000-11200 ft) | 1400-2800 m (4600-9200 ft) |
Distribution |
CA; CO; ID; MT; OR; UT; WA; WY; AB; BC
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MT; AB |
Discussion | Stellaria americana is remarkable for its tortuous fruiting pedicels, which push the opening capsule with its small number of large seeds into the substrate. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 5, p. 110. | FNA vol. 5, p. 100. |
Parent taxa | Caryophyllaceae > subfam. Alsinoideae > Stellaria | Caryophyllaceae > subfam. Alsinoideae > Stellaria |
Sibling taxa | ||
Synonyms | Alsine obtusa, Alsine viridula, Alsine washingtoniana, S. viridula, S. washingtoniana | S. dichotoma var. americana, Alsine americana, Arenaria stephaniana var. americana |
Name authority | Engelmann: Bot. Gaz. 7: 5. (1882) | (Porter ex B. L. Robinson) Standley: Contr. U. S. Natl. Herb. 22: 336. (1921) |
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