Nodding Wild Onion is an edible native perennial forb growing to 1-1/2 feet high to the top of the erect flowering stem.
The leaves are all basal and form a rosette, rising in a vase shape before bending outward and downward. Leaves are linear, flat, solid, with a center ridge which can create a slight "v" shape, and parallel veins. They are much shorter than the flower stalk and have a basal sheath, which is usually not seen above ground level.
The inflorescence is an umbel of numerous (8 to 35) stalked nodding flowers. The umbel is atop a round smooth greenish scape (a flowering stem that arises directly from the roots). The entire flower head "nods" as the top of scape bends over. The base of the umbel has two thin lanceolate shaped bracts. The scape may be ridged or angled and flattened at the top where it bends.
The flowers are whitish to pink, small, bell shaped, 6-parted, about 1/4 inch long with three sepals and three petals combined to form six tepals. The margins of the 3 outer tepals are incurved. There are six exserted stamens that have white filaments and yellow anthers. The single style is about as long as the stamens and has a blunt slightly thickened tip. After pollination the flower head bends upward.
Fruit: The flowers produce a seed capsule, not bulblets. The capsule elongates and bends upward with the flower head, eventually exposing roundish black seeds that can have a shiny or dull surface. These are usually wind dispersed. Seeds require 60 days of cold stratification for germination.
Habitat: Nodding Wild Onion grows from a thinly oblong elongate shape bulb, much longer than wide, 1/2 to 3/4 inches in diameter, which can create offsets to produce a clump of plants. The bulb may have short rhizomes at its base. It prefers partial shade in cooler areas and accepts a variety of soils with wet-mesic to dry-mesic moisture conditions. In full sun in open areas of prairies, hillsides and gardens it will grow and flower well with adequate moisture.
Names: The genus, Allium, is Latin for garlic. The base word of the species name, cernuum, means nodding or drooping. The author name for the plant classification - ‘Roth’ is for Albrecht Wilhelm Roth (1757-18340 German botanist who published his research and was later associated with the University of Jena Botanical Institute. All older references will list this species in the Lily Family (Liliaceae). Some botanists has created a new family specifically for the New World Allium. Some others have included a few Old World Allium in the new family and some have only included a portion of the New World Species. This family arrangement is still in flux, although the Minnesota Authorities at the U of M Herbarium have adopted the new family for the 7 of the New World Allium. Flora of North America has noted the many proposals but not yet published them.
Comparisons: Nodding Wild Onion is distinguished from Wild Garlic, A. canadense, by the the lack of bulblets produced in the inflorescence. It is closest in resemblance to Wild Onion, A. stellatum and that species has a nodding inflorescence also, but only in the bud stage, after which it becomes erect. Also the bulb of A. stellatum is more ovoid, less elongated (photo below) and the flower tepals form a star-like appearance, not a bell like shape.
Above: The flowering scapes rise well above the clump of basal leaves. Drawing ©Flora of North America.
Below Flowers of early to late August. Note the outer three tepals have incurved margins.
Below: Both A. cernuum and A. stellatum have the scape nodding in the bud stage. The former stays nodding while the latter becomes erect.
Below: 1st photo - the nodding inflorescence in bud stage. 2nd photo - The mature seed capsule contains several black hard seeds. 3rd photo - The bulb of Nodding Wild Onion is an elongated shape.
Below: Bulb comparison of A. stellatum (left) and A. cernuum (right). The former is more conical and usually has some grayish or brownish membranous material attached to the bulb.
Notes: Nodding Wild Onion is not indigenous to the defined Garden area. In her Garden Log Eloise Butler reports planting three plants in the Garden on May 9, 1910 that were obtained from Kelsey's Nurseries in NC. However, on August 8, 1911 she brought in additional plants collected in Glenwood Park (which surrounds the Garden and is now named Theodore Wirth Park) and 4 more plants on Aug. 2, 1914 from Twin Lake. More were added in 1918 and '19 and by Martha Crone in 1945. These may be mistaken designations as the species is not known to be native to those areas where plants were sourced, except for Kelsey's and therefore the plants brought in were probably A. stellatum, which, as explained above can be confusing. Although A. cernuum is the most widespread species of Allium in North America, it is not widespread in Minnesota contrary to all the published references. The MN DNR reports (see PDF) that it is native to only four counties in the SE section of MN and in fact, was not even known to be in Minnesota until 1981 and for this scarcity, it is of concern and is listed as a "Special Concern" species on the Minnesota rare plants list. No subspecies are recognized in Minnesota. You will find reports, including on the USDA site, that it is widespread in Minnesota, but those sighting are probably confused with A. stellatum.
Nodding Wild Onion is one of is one of six Allium species known to Minnesota plus one which is considered a garden hybrid. The six natives are: A. canadense, Wild Garlic; A. cernuum, Nodding Wild Onion; A. schoenoprasum, Wild Chives; A. stellatum, Prairie Onion; A. textile, White Wild Onion; and A. tricoccum, Wild Leek: Four of the species are found in the Garden - A. cernuum and the three with links to information sheets.
Eloise Butler wrote of this plant: ". . . pink balls of fairy grace lifted on slender, leafless stalks give a magical brilliancy to the billowing grasses of large expanses of the prairie. Do not be disconcerted by the name. The onion is, after all, a sort of lily, considered by every one a flower queen, and the odor is not perceptible, except when the plant is bruised. The leaves of this Allium are very narrow, unlike those of the early leek, so abundant in the wood in early spring." Published Aug. 20, 1911, Minneapolis Sunday Tribune.
Lewis & Clark: In the History of the Lewis and Clark Expedition (Ref.#3b) the following is recorded on July 22, 1805 in Montana on the Missouri River: "There is a large island, forming in the middle of a bend to the north a level fertile plain, ten feet above the surface of the water and never overflowed. Here we found great quantities of a small onion [Allium cernuum] about the size of a musketball, though some were larger; it is white, crisp, and as well flavored as any of our garden onions [A. cepa]; the seed is just ripening, and as the plant bears a large quantity to the square foot, and stands the rigors of the climate, it will no doubt be an acquisition to the settlers. From this production we called it Onion Island."
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"