Allium cernuum

Nodding onion

Liliaceae

The Basics

Taxonomy: Kingdom - Plantae (plants). Subkingdom - Tracheobionta (vascular plants). Superdivision - Spermatophyta (seed plants). Division - Magnoliophyta (Flowering plants). Class - Liliopsida (Monocotyledons). Subclass - Liliidae. Order - Liliales. Family - Liliaceae (Lily familly). Genus -Allium L. Species - Allium cernuum Roth.

Ecology: Allium cernuum is a perennial monocot that flowers from July through October. It is the most widespread Allium is North America. It is a shade-intolerant, montane to subalpine, transcontinental North American forb. Occurs on nitrogen-medium, water-shedding sites within boreal, temperate, and cool mesothermal climates. Its occurrence decreases with increasing precipitation and latitude. Occasional in early-seral communities on shallow soils of rock outcrops; frequently inhabits exposed mineral soils. Characteristic of summer-dry temperate and mesothermal forests.

Identification

General: Perennial herb from an elongate, long-necked, narrowly egg-shaped, scaly bulb, the outer scales membranous, without a fibrous network, the inner scales faintly pinkish, the bulbs often clustered; flowering stems erect but down-curved near the top, 10-50 cm tall, slender, often somewhat angled, smooth. Has 2-5+ bulbs, clustered, often short-rhizomatous at base, rhizome not stout or iris-like, oblong, elongate, 1–3 × 0.8–1.5 cm; outer coats enclosing 1 or more bulbs, grayish or brownish, membranous, minutely striate, cells in regular vertical rows, narrowly elongate, fibers persistent, parallel, few; inner coats white to pink or reddish, cells in regular vertical rows, narrowly elongate. Leaves persistent, green at anthesis, 3–5, basally sheathing, sheaths not extending much above soil level; blade solid, flat, channeled to broadly V-shaped in cross section, 10–25 cm × 1–6 mm, margins entire or denticulate. Scape persistent, sometimes 2 or more produced successively from single bulb, usually clustered, nodding, solid, terete or ridged, particularly distally, sometimes flattened and narrowly winged, abruptly recurved near apex, 10–50 cm × 1–3 mm. Umbel persistent, cernuous, loose, 8–35-flowered, hemispheric, bulbils unknown; spathe bracts persistent, 2, 3-veined, lanceolate, ± equal, apex acuminate, beakless. Flowers campanulate, 4–6 mm; tepals ± erect, pink or white, elliptic-ovate, ± equal, withering in fruit, margins ± entire, apex ± obtuse, at least outer tepals strongly incurved, midribs not thickened; stamens exserted; anthers yellow; pollen yellow; ovary conspicuously crested; processes 6, flattened, ± triangular, margins entire or toothed; style exserted, linear, ± equaling stamens; stigma capitate, scarcely thickened, unlobed; pedicel 6–25 mm, becoming stouter in fruit, elongating and bending abruptly upward from near point of attachment. Seed coat dull or shining; cells smooth, minutely roughened, or each with minute, central papilla.

Leaves: Basal leaves several per bulb, linear, flat to channeled, shorter than the flowering stem, about 3 mm wide, smooth, the margins entire or minutely toothed; stem leaves lacking.

Flowers: Inflorescence a compact, terminal, nodding umbel of several to many, stalked flowers, above 2 membranous bracts, the stalks 1-3 cm long, the bracts soon deciduous; flowers pink to rose-purple or whitish, bell-shaped, of 6 distinct tepals, the tepals 4-6 mm long, elliptic-egg-shaped, blunt; stamens 6, exserted; pistil 1, 3-chambered.

Fruits: Capsules, more or less egg-shaped, 3-lobed, with 6 crests, 2 on each lobe; seeds 6 or fewer, dull-black.

Reproduction

Flowering and Fruiting - Umbel few-to many-flowered, the slender pedicels 2-3 times the length of the tepals; perianth bell-shaped, the 6 segments 4-6 mm. long, elliptic-ovate, obtuse, entire, pink or white; stamens 6, exerted; style filiform, exerted; stigma capitate. Fruits - capsule 3-celled, crested with 6 distinct, flattened processes. Allium cernuum occurs on both sides of the Cascades crest in Washington; British Columbia south to Oregon, east to the Rocky Mountains; also in central and southeastern U.S. It can be found in open, somewhat moist areas, sea level to high elevations in the mountains. Allium cernuum is the most widespread North American species of the genus.

Species Distribution

Citation

E-Flora of British Columbia
In Klinkenberg, Brian. (Editor) 2017. E-Flora BC: Electronic Atlas of the Plants of British Columbia [eflora.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver.

USDA Plants Database
USDA, NRCS. 2017. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA.
Distribution Map photo Credit

Burke Museum of Natural History and Culture
Burke Museum. 2017. Allium cernuum [Online]. University of Washington

Photo credit: 2004, Ben Legler.

Flora of North America
Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 19+ vols. New York and Oxford.

Jepson eFlora
Dale W. McNeal 2017. Allium, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=9889, accessed on March 06, 2017..