Allium rotundum |
Allium cratericola |
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Cascade onion |
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Bulbs | 1–50+, ovoid, 0.2–1.5 × 0.2–1 cm; outer coats surrounding numerous, very dark purple bulbels, usually white or greenish, membranous, sometimes breaking into ± parallel, fibrous strips; inner coats white, cells obscure, quadrate. |
1–3, not clustered on stout primary rhizome, ovoid, 1.5–2.5 × 1–2 cm; outer coats enclosing 1 or more bulbs, brown or gray, membranous, lacking cellular reticulation or cells arranged in only 2–3 rows distal to roots, ± quadrate, without fibers; inner coats white, cells obscure, ± quadrate, or not visible. |
Leaves | persistent, 2–5, sheathing 1/3–1/2 scape; blade solid, flat or channeled, carinate, 15–40 cm × 2–5(–7) mm, margins entire. |
usually deciduous with scape, withering from tip at anthesis, 1–2, basally sheathing, sheaths not extending much above soil surface; blade solid, straight or weakly falcate, flat or broadly channeled, 10–30 cm × 1–21 mm, margins entire. |
Scape | persistent, solitary, erect, ± solid, 25–90 cm × 1–4 mm. |
usually forming abcission layer and deciduous with leaves after seeds mature, frequently breaking at this level after pressing, solitary, erect, solid, terete, 2–12 cm × 1–3 mm. |
Umbel | persistent, erect, very dense, 80–200-flowered, globose, bulbils unknown; spathe bracts caducous, 2, 7–12-veined, lanceolate, ± equal, apex narrowed to beak, beak to 2 cm. |
persistent, erect, compact, 20–30-flowered, hemispheric, bulbils unknown; spathe bracts persistent, 2–4(–6), 10–16-veined, ovate, ± equal, apex acuminate. |
Flowers | campanulate, 4–7 mm; tepals erect, purple, or inner with broad whitish margins and purple midvein, oblong to ovate, ± equal, becoming keeled and ± rigid in fruit, margins entire, apex acute to obtuse; stamens included; filaments: outer unlobed, inner with 2 prominent teeth on either side of anther, teeth 2–3 times anther-bearing portion, usually papillose to ciliate; anthers yellow or purple; pollen light yellow to white; ovary crestless; style linear, ± equaling anther-bearing portion of stamens; stigma capitate, unlobed; pedicels 5–30 mm, outer much shorter than inner. |
campanulate, 7–14 mm; tepals erect, white or pink to purplish with dark greenish brown or purple midveins, lance-oblong, elliptic, or ± oblanceolate, ± equal, becoming papery and investing fruit, margins entire, apex obtuse; stamens included; anthers yellow; pollen yellow; ovary crested; processes 3, central, rounded, minute, margins entire; style linear, equaling stamens; stigma capitate, scarcely thickened, unlobed; pedicel 5–18 mm. |
Seed | coat dull; cells each with central papilla. |
coat dull; cells ± smooth. |
2n | = 14, 28. |
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Allium rotundum |
Allium cratericola |
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Phenology | Flowering May–Jul. | Flowering Mar–Jun. |
Habitat | Disturbed fields and roadsides | Serpentine, volcanic, and granitic soil |
Elevation | 300–1800 m (1000–5900 ft) | |
Distribution |
MI; c Europe; s Europe [Introduced in North America] |
CA
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Discussion | Allium rotundum is native to central and southern Europe. It is reported as established in southern Michigan, and is to be expected elsewhere in the Great Lakes region. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Populations of Allium cratericola from southern California are 2-leaved, while those from the north are either 1- or 2-leaved or sometimes a mixture of both forms. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 26, p. 244. | FNA vol. 26, p. 271. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | A. parvum var. brucae, A. parvum var. jacintense | |
Name authority | Linnaeus: Sp. Pl. ed. 2, 1: 423. (1762) | Eastwood: Leafl. W. Bot. 1: 132. (1934) |
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