Allium cernuum is a herbaceous perennial growing from an unsheathed elongated conical bulb which gradually tapers directly into several keeled (thin and flat) grass-like leaves, 2–4 millimetres (3⁄32–5⁄32 inch) in width. Each mature bulb bears a single flowering stem, which terminates in a downward nodding umbel of white or rose, campanulate (bell-shaped) flowers that bloom in July and August. The flowers are arranged into downward facing umbels and each flower is about 5 mm (3⁄16 in) across, pink or white with yellow pollen and yellow anthers. A. cernuum does not have bulblets in the inflorescence.[5] The flowers mature into spherical crested fruits which later split open to reveal the dark shiny seeds.[6][7][8][9][10][11][12][13]
Despite its wide geographical distribution, it is absent from much of its range. In the southern part of its range in North America it is limited to mountainous habitats, and in other parts of its North American range it is limited to local and disjunct population. It is absent from North Dakota and most of the Great Plains states and intermountain region of the U.S.[5] In Minnesota it is listed as a threatened species.[19]
It can be found growing in deciduous woodlands, to open grasslands.[5]
It is grown in gardens for its distinctive nodding flowers that are white, pink, or maroon; it is winter hardy in U.S. Department of Agriculturehardiness zones 3–9.[4] In gardens it will often form dense clusters of bulbs over time from offsets of the parent bulb.[21] Plants are healthiest in full sun with well drained soil, though in hot climates they appreciate some shade especially in the afternoons.[20]
^Gleason, H. A.; Cronquist, A.J. (1991). Manual of the Vascular Plants of Northeastern United States and Adjacent Canada (2 ed.). Bronx: New York Botanical Garden. pp. i–910.
^Cronquist, A.J.; Holmgren, A. H.; Holmgren, N. H.; Reveal, J. L. (1977). "Vascular Plants of the Intermountain West, U.S.A.". In Cronquist, A.J.; Holmgren, A. H.; Holmgren, N. H.; Reveal, J. L.; Holmgren, P. K. (eds.). Intermountain Flora. Vol. 6. New York: Hafner Pub. Co. pp. 1–584.
^Hitchcock, C. H.; Cronquist, A.J.; Ownbey, F. M.; Thompson, J. W. (1969). "Vascular Cryptogams, Gymnosperms, and Monocotyledons". In Hitchcock, C. L. (ed.). Vascular Plants of the Pacific Northwest. Vol. 1. Seattle: University of Washington Press. pp. 1–914.
^Radford, A. E.; Ahles, H. E.; Bell, C. R. (1968). Manual of the Vascular Flora of the Carolinas. Chapel Hill: University of North Carolina Press. pp. i–lxi, 1–1183.
^Barr, Claude A. (1983). Jewels of the plains : wild flowers of the Great Plains grasslands and hills. Minneapolis: University of Minnesota Press. p. 19. ISBN0-8166-1127-0.