Allium unifolium (one-leafed onion)

Plant Description: A perennial native to California and Oregon, Allium unifolium can be hard to find in our natural environments. It is important therefore, that we steward them by buying their native bulb, seed, or starts and not take them from their natural habitat. They have slender green herbaceous basal leaves that stem from a small conspicuous bulb. The bulbs grow densely together creating clusters of plants that can be dived regularly. Each plant produces one light purple loose umbel shaped flower head with a peduncle that is between 12in - 24in. Flowers tend to bloom between May and June. Allium unifolium reproduce through starchy rhizomes and seed. 

• Height: 12 - 24in
• Width: 12 in (clustered plants can take up much more space)
• Watering needs: moist to wet
• Sun needs: full sun to partial shade
• Soil needs: well draining moist clay or serpentine soils
• Bloom Time: May - June
• Portland Plant List (Backyard Habitat Certification): No

Landscape Use and Ecological Function: Primarily found in moist to wet clay soils in riparian areas, such as stream banks, Allium unifolium create clumps of onion bulbs that help to break up clay soils and prevent erosion. They are great source of food for pollinators and some small mammals, but their onion smell tends to deter mammals such as deer and rabbits.