Allium rotundum |
Allium bisceptrum |
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twincrest 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. |
1–7+, commonly producing either cluster of stalked, basal bulbels or filiform rhizomes to 1 dm, terminated by bulbels, rhizomes generally lost when specimens are collected, ovoid, 1–2 × 0.6–1.8 cm; outer coats enclosing 1 or more bulbs, light brown to gray, membranous, obscurely cellular-reticulate, cells rectangular, walls minutely sinuous, vertical, varying to irregular, all sinuous, without fibers; inner coats white to pink, cells obscure, quadrate. |
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. |
persistent, green at anthesis, 2–5, basally sheathing, sheaths not extending much above soil surface; blade solid, flat, broadly channeled, 8–30 cm × 1–13 mm, margins entire. |
Scape | persistent, solitary, erect, ± solid, 25–90 cm × 1–4 mm. |
persistent, solitary or clustered 1–3, erect, solid, terete, 10–30(–40) cm × 1–5 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, loose, 15–40-flowered, globose, bulbils unknown; spathe bracts persistent, 2, 3–4-veined, ovate to lanceolate, ± 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. |
stellate, 7–10 mm; tepals spreading, lilac to white, lanceolate, ± equal, becoming papery in fruit, not carinate, margins entire, apex acuminate, not involute; stamens included; anthers purple; pollen yellow; ovary conspicuously crested; processes 6, central, distinct, flattened, triangular, margins papillose-denticulate; style included, linear, ± equaling stamens; stigma capitate, unlobed; pedicel 10–20 mm, often becoming flexuous and deflexed in fruit. |
Seed | coat dull; cells each with central papilla. |
coat shining; cells each with minute, central papilla. |
2n | = 14, 28. |
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Allium rotundum |
Allium bisceptrum |
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Phenology | Flowering May–Jul. | Flowering May–Jul. |
Habitat | Disturbed fields and roadsides | Meadows and aspen groves, less commonly on open slopes in mountains |
Elevation | 1100–3000 m (3600–9800 ft) | |
Distribution |
MI; c Europe; s Europe [Introduced in North America] |
AZ; CA; ID; NM; NV; OR; UT
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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.) |
Two varieties of Allium bisceptrum have been recognized. Where their ranges overlap (central Utah and central Nevada), the putative varieties cannot be distinguished confidently except by chromosome number. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 26, p. 244. | FNA vol. 26, p. 256. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | A. bisceptrum var. palmeri, A. bisceptrum var. utahense, A. palmeri | |
Name authority | Linnaeus: Sp. Pl. ed. 2, 1: 423. (1762) | S. Watson: Botany (Fortieth Parallel), 351, plate 37, figs. 1–3. (1871) |
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