This plant is easy to identify because of the nodding habit of the flowers. Nodding umbels of flowers are an evolutionary adaptation that tends to restrict insect visitors to bees. Other insects are more reluctant to hang upside down while attempting to feed on nectar or pollen. The nodding habit may also protect the nectar from rain. The Nodding Onion is available in the nursery trade, which often features cultivars with rosy pink flowers. Return

This native perennial plant consists of a vase-like rosette of basal leaves. The leaves are about 12' long and up to ¼' across. They are linear in shape, with smooth margins and parallel venation. Unlike many onions from the Old World, the leaves are solid and flat, and there is a small ridge running along their length. They are rather soft and tend to bend outward or downward. From the center of the rosette, a single flowering scape may appear that is about 1½' tall. This scape terminates in an umbel of flowers. This umbel faces toward the ground because the scape bends downward at its apex. The flowers are individually about ¼' long, and may be white, light lavender, or pink. A flower consists of 3 petals and 3 sepals (i.e., tepals) with a similar appearance, and has 6 white stamens with yellow anthers. The pedicels are about ¾' long. At the base of the umbel are two membraneous bracts that soon fall off. The blooming season is usually mid-summer and lasts about a month. There is no floral scent. The flowers are replaced by seed capsules containing small black seeds that are light in weight and rather flat. They are distributed to a limited extent by the wind. The root system consists of a bulb that is longer than it is wide. Both the bulb and foliage have a typical onion-like scent. Offsets frequently form, creating small clumps of plants.

Nodding Onion is an uncommon plant that occurs only in NE Illinois (see Distribution Map). Habitats include moist to mesic black soil prairies, sandy pannes near dunes, and rocky bluffs. Much of the prairie habitat where this plant once occurred has been destroyed by development. It is more likely to be observed in high quality habitats than disturbed areas.

Allium neomexicanum Rydb.:
Mexico (Mesoamerica)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Allium allegheniense Small:
United States (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Allium cernuum Roth:
Canada (North America)
United States (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Alta., B.C., Ont., Sask.; Ala., Ariz., Ark., Colo., D.C., Ga., Idaho, Ill., Ind., Iowa, Ky., Md., Mich., Minn., Mo., Mont., Nebr., N.Mex., N.Y., N.C., Ohio, Oreg., Pa., S.C., S.Dak., Tenn., Tex., Utah, Va., Wash., W.Va., Wis., Wyo.; Mexico.

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Western North Carolina, western Virginia, and eastern West Virginia, possibly more widespread (Weakely 2000).

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Endemic to West Virginia, although it might also occur in adjacent Virginia. It has been reported falsely from Virginia thus far, but it is likely to exist (T. Wieboldt, pers. comm., 1995).

United States

Origin: Unknown/Undetermined

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

United States

Origin: Unknown/Undetermined

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

Canada

Origin: Unknown/Undetermined

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Bulbs 2–5+, 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. 2n = 14.

Allium allegheniense Small; A. oxyphilum Wherry; A. recurvatum Rydberg

Flowers white; pedicels 2-4 cm long; perianth segments are obtuse (Strausbaugh & Core, 1978).

Possible syntype for Allium neomexicanum Rydb.
Catalog Number: US 563680
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Original publication and alleged type specimen examined
Preparation: Pressed specimen
Collector(s): E. O. Wooton
Year Collected: 1894
Locality: Organ Mountains, Dona Ana, New Mexico, United States, North America

Holotype for Allium oxyphilum Wherry
Catalog Number: US 1241244
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Original publication and alleged type specimen examined
Preparation: Pressed specimen
Collector(s): W. Wherry
Year Collected: 1924
Locality: Lillydale., Monroe, West Virginia, United States, North America

Nodding Onion is an uncommon plant that occurs only in NE Illinois (see Distribution Map). Habitats include moist to mesic black soil prairies, sandy pannes near dunes, and rocky bluffs. Much of the prairie habitat where this plant once occurred has been destroyed by development. It is more likely to be observed in high quality habitats than disturbed areas.

Widely distributed on moist soils in mountainous and cool regions; 600--3500m.

Comments: Occurs on acid soils (Strausbaugh & Core, 1978). Most occurrences in West Virginia are on shale barrens, but this species has been noted on sandstone outcroppings as well.

The flowers are pollinated by small short-tongued bees, such as Halictid bees. Syrphid flies may visit the flowers as well, but they are feeding on the pollen and are non-pollinating. Mammalian herbivores usually don't eat Allium spp., although livestock may consume the foliage along with the grass in pastures, which can provide milk with an off-flavor.

Allium cernuum (Nodding Onion)
(Halictid bees suck nectar or collect pollen, while other insects suck nectar; all observations are from Graenicher)

Bees (long-tongued)
Apidae (Apinae): Apis mellifera sn; Apidae (Bombini): Bombus pensylvanica sn, Bombus ternarius sn; Anthophoridae (Anthophorini): Anthophora terminalis sn, Anthophora walshii sn; Anthophoridae (Xylocopini): Xylocopa virginica sn; Megachilidae (Megachilini): Megachile centuncularis sn

Bees (short-tongued)
Halictidae (Halictinae): Lasioglossum albipennis cp, Lasioglossum forbesii sn cp, Lasioglossum imitatus cp, Lasioglossum zephyrus cp; Colletidae (Colletinae): Colletes eulophi sn

Flies
Syrphidae: Tropidia quadrata sn

Butterflies
Pieridae: Pieris rapae sn

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 6 - 20

Comments: There are eighteen extant occurrences of this element.

In West Virginia, Allium oxyphilum occurs at 18 sites. The largest population consists of 18,000 plants occurring in several subpopulations. The shale barren is on a south-facing slope with areas of open xeric hardwoods with a grass-sedge understory, shale and sandstone ledges, and xeric grass balds. It is often found on bare shale at this site, and it is most common in the more open areas. At other sites, it has been found in acidic and calcareous soils and atop boulders. Most populations in West Virginia contain 100-400 plants. Although populations are medium-sized and need revisited, the species appears stable in the state.

Flowering Jul--Oct.

Sexual reproduction. Bumblebees have been noted pollinating this species (R. Bartgis, pers. comm., 1985).

The following is a representative barcode sequence, the centroid of all available sequences for this species.


No available public DNA sequences.

Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 1
Specimens with Barcodes: 3
Species With Barcodes: 1

Rounded Global Status Rank: TNR - Not Yet Ranked

United States

Rounded National Status Rank: N3 - Vulnerable

Rounded Global Status Rank: G3 - Vulnerable

Reasons: Occurs in western North Carolina, western Virginia, eastern West Virginia, and possibly elsewhere, in thin soils around mafic or calcareous rock outcrops (Weakely 2000). Uncommon in its known range (Weakley 2000).

United States

Rounded National Status Rank: N2 - Imperiled

Rounded Global Status Rank: G2 - Imperiled

Reasons: This species is a regional endemic (possibly only one state), but has taxonomic questions. It is found chiefly on shale barrens, and most populations have fewer than 500 plants.

United States

Rounded National Status Rank: NNR - Unranked

United States

Rounded National Status Rank: NNR - Unranked

Rounded Global Status Rank: T5 - Secure

Reasons: Widespread on open slopes and meadows in western New Mexico, into southeastern Arizona and Mexico.

Canada

Rounded National Status Rank: NNR - Unranked

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Global Short Term Trend: Relatively stable (=10% change)

Comments: All occurrences are extant with average to good populations. Populations at one site have fluctuated and may be decreasing.

Comments: The habitat of A. oxyphilum is generally unsuitable for development. It may be subject to grazing and trampling, as well as habitat destruction from powerline and road construction. Invasive plant species may also be a threat. Somewhat threatened by forest management practices and lack of disturbance resulting in succession (Southern Appalachian Species Viability Project 2002).

Comments: Somewhat threatened by land-use conversion (quarrying) and habitat fragmentation (Southern Appalachian Species Viability Project 2002).

Restoration Potential: Once the habitat has been degraded by major alterations, such as bulldozing, it would be difficult to restore it. Sites that have been trampled or grazed could be fenced or posted. Allium oxyphilum grows in harsh environments and can probably tolerate some disturbance. One site was created by road construction.

Preserve Selection and Design Considerations: Preserve design should include entire suitable habitat, as well as a buffer area. As succession takes place, the shale barrens will likely need management to keep woody vegetation to a minimum.

Management Requirements: In order to manage for Allium oxyphilum, shale barrens should be managed as a whole habitat. This would include minimizing foot travel, discontinue any grazing, and cutting back woody vegetation.

Monitoring Programs: Allium oxyphilum is not being monitored specifically by The Nature Conservancy although they have been monitoring and surveying shale barrens throughout Virginia, West Virginia and Maryland.

Management Research Programs: There are no known management research programs.

Biological Research Needs: The most crucial research needed for Allium oxyphilum is to determine if it is a valid taxon or a variety or form of Allium cernuum.

Needs: Since several sites in West Virginia are already protected, additional protection is probably not needed. The exemplary site, though on private property, is protected as part of a large resort. The resort is aware of the rare species at this site and there are no intentions to develop the area.

The preference is full or partial sun, and moist to mesic conditions. The soil can consist of black loam, or contain either rocky or sandy material. This plant resents hot, dry summers. It usually isn't bothered by foliar disease. This plant is easy to grow, and will spread gradually under suitable conditions. It is easier to establish plants by transplants from offsets, rather than by attempting to germinate the seeds.

Comments: No known economic uses, although the species is probably edible, and could be used in cooking.

Stewardship Overview: Management for Allium oxyphilum should not be species-specific, but should encompass the habitat. This species occurs mostly on shale barren habitat, which is a rare community and harbors many shale barren endemics. Management would involve limiting succession by cutting back woody vegetation, minimizing foot travel, and discontinuing any grazing on shale barren habitat. Prevent entry of invasive, exotic species.

Allium cernuum is the most widespread North American species of the genus. It is closely related to A. stellatum, and the character commonly used to differentiate them has been umbel orientation. In both species, the inflorescence is nodding in bud, but in A. stellatum it usually becomes erect by anthesis. In A. cernuum the peduncle remains permanently recurved near the apex, although the inflorescence may sometimes become erect overall, or nearly so. While this character is helpful in identification, an almost exclusive reliance on it (even by one of the present authors in his youth) has obscured other clearer distinctions between the species and has confused their geographic ranges. More reliable characters for differentiating these species are bulb shape (elongate in A. cernuum, ovoid in A. stellatum) and perianth shape (campanulate in A. cernuum, stellate in A. stellatum). Unfortunately, perianth shape is often difficult to see in herbarium specimens.

Comments: Recognized as distinct from Allium cernuum by Kartesz in his 1999 Floristic Synthesis.

Comments: Maintained as a distinct species by Kartesz (1994 and 1999). Kartesz notes (pers. comm. to Larry Morse, Nov. 1999) that he is not aware of any recently published work questioning this species' distinctiveness. However, Barbara Sargent and Dean Walton, West Virginia Heritage Program, noted in 1995 that A. oxyphilum, if studied further, might prove to be a variety or form of the widespread species Allium cernuum. Larry Morse, 10Dec99.