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Flat Stemmed Onion Back to Plant Page
Allium platycaule

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About Flat Stemmed Onion (Allium platycaule) Allium platycaule is a species of wild onion known by the common name broadstemmed onion or flat-stem onion. It is native to northeastern California and nearby parts of Oregon and Nevada where it is found on slopes of some elevation. This onion grows from a gray bulb two to three centimeters wide and has a flattened stem which may bulge in the middle and narrow to thin wings along the sides. The long, flat leaves are sickle-shaped. Atop the stem is an flower cluster which may have as many as 90 flowers in it. Each flower may be up to a centimeter and a half wide but the petals are quite narrow so as to be almost threadlike. The flower cluster therefore may be a dense ball of filaments. The flowers are generally bright pink to magenta. The leaves, bulbs, and seeds were utilized as food by the Paiute people.
Plant Description
Plant Type
Perennial herb

Flower Color

Flowering Season

Native Status

Natural Setting
Site Type
Rocky or sandy slopes


Elevation ?
947' - 10194'

Annual Precip. ?
12.4" - 120.2"

Summer Precip. ?
0.28" - 4.08"

Coldest Month ?
25.5° F - 43.2° F

Hottest Month ?
46.2° F - 73.6° F

Humidity ?
1.03 vpd - 19.93 vpd


Sunset Zones ?
1, 2, 3, 7, 14, 15, 16, 17, 18

Landscaping Information
Ease of Care
Moderately Easy

Water Requirement ?
Very Low
Extremely Low
Very Low
Moderate - High

Common uses
Bee Gardens

Nursery Availability
Rarely Available

Other Names
Common Names
Flat-stem Onion, Broadstemmed Onion

Sources include: Wikipedia. All text shown in the "About" section of these pages is available under the Creative Commons Attribution-ShareAlike License. Plant observation data provided by the participants of the California Consortia of Herbaria, Sunset information provided by Jepson Flora Project. Propogation from seed information provided by the Santa Barbara Botanical Garden from "Seed Propagation of Native California Plants" by Dara E. Emery. Sources of plant photos include CalPhotos, Wikimedia Commons, and independent plant photographers who have agreed to share their images with Calscape. Other general sources of information include Calflora, CNPS Manual of Vegetation Online, Jepson Flora Project, Las Pilitas, Theodore Payne, Tree of Life, The Xerces Society, and information provided by CNPS volunteer editors, with special thanks to Don Rideout. Climate data used in creation of plant range maps is from PRISM Climate Group, Oregon State University, using 30 year (1981-2010) annual "normals" at an 800 meter spatial resolution.

Links:   Jepson eFlora Taxon Page  CalPhotos  Wikipedia  Calflora

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