Allium cernuum, Nodding Onion

🌱 See PLANT FACTS in sidebar.

Nodding Onion usually stands only 18″ high, its low grass-like onion foliage sending up a long arching green stem from which hangs a cluster of pale pinkish purple flowers in July. Native bees hang from the delicate, long-stamened flowers to gather nectar and pollen, making for a charming sight.

Cultivation

Plant in masses for a stunning display. Thrives best in at least semi-moist (mesic) soil but can be grown on dry shady or barren sunny banks and rock gardens, especially here in the mountains where it is more tolerant of poor soils the higher in elevation it grows (Digital Atlas of the Virginia Flora). It is very tolerant of limestone and calcium. Because it is not highly competetive but can survive poor dry soils at higher elevations, it is found in outcrop barrens in Virginia where weed competition is low.

Allium cernuum is often included in prairie or wildflower mixes and blends nicely with shorter grasses and perennial flowers. Make sure to follow the maintenance plan for your prairie planting to encourage the persistence and regeneration of desired species like Allium cernuum.

Human Uses

According to Wikipedia, “Although it is important to distinguish from poisonous deathcamas, the plant is edible and has a strong onion flavor, often used in cooking.” Wildflower.org adds “All parts poisonous but causes only low toxicity if eaten; can be safely eaten in small amounts, large quantities not recommended. Symptoms may include nausea, vomiting, diarrhea. Toxic Principle: Sulfides.”

Ecology

This native onion is identified by the Xerces Society as being of Special Value to Native Bees, as well as Supporting Conservation Biological Control by attracting predatory wasps that prey on pest insects (Wildflower.org). Butterflies, hummingbirds, and bees forage on nectar, bulbs are eaten by bears and ground squirrels, and elk and deer graze the early spring herbage. Attracts the Hairstreak Butterfly. (Wildflower.org)

Virginia Heritage Communities

Allium cernuum is a characteristic member of the globally rare and imperiled ecosystem found only at Buffalo Mountain called Wooded Herbaceous Vegetation Southern Blue Ridge Low-Elevation Mafic Barren [USNVC CEGL006215, Quercus stellata / Schizachyrium scoparium – Andropogon gerardii – Pycnanthemum tenuifolium – Packera paupercula Wooded Grassland (G1/S1)]. This unique community of plants is a type of Low-Elevation Outcrop Barren.

**Please do not hike off trail at Buffalo Mountain to try to glimpse these globally rare habitats. They are fragile, protected, and cared for closely by Virginia DCR. Collecting plants or seeds from protected areas is strictly prohibited.**

While this Allium enjoys moist soils, it can only maintain a longterm presence in maturing ecosystems that are xeric such as barrens, where it won’t be overwhelmed and shaded out by thicket and forest. Allium cernuum is a defining member of some of these western Virginia barrens:

• Limestone Annual Flatrock Barren [USNVC CEGL007073, Juniperus virginiana) / Sporobolus vaginiflorus – Panicum flexile – Allium cernuum – Minuartia patula Herbaceous Vegetation (G1/S1)], a globally imperiled type of Limestone / Dolostone Woodlands and Barren
• Central Appalachian Mafic / Calcareous Barren (Mid-Elevation Type) [USNVC CEGL008529, Fraxinus americana / Physocarpus opulifolius / Carex pensylvanica – Allium cernuum – (Phacelia dubia) Wooded Herbaceous Vegetation) (G2/S2)] a type of Low-Elevation Outcrop Barren.

Nearby, Montgomery County has many Limestone / Dolostone Woodlands and Barrens in the Pedlar Hills where Allium cernuum grows.

**The Pedlar Hills are protected natural areas and wild collecting plants or seeds is strictly prohibited.**