On these pages photos of North American Allium species will be featured. There are approximately 130 taxa in North America, almost half of which occur in California as the center of diversity. Besides a few species that are widely grown, namely Allium cernuum (nodding onion), the Californian A. unifolium (popularized by the Dutch bulb trade) and the lesser known A. stellatum (prairie onion), the North American onion species have been largely ignored by the horticultural world. There are also about 15 species native to Mexico, similarly rare or absent from horticulture. Eastern American species generally need a cool - cold winter dormancy period with some to lots of rain. Western American species, especially those in the Pacific States follow a Mediterranean pattern where they need a moderately cold wet winter and a cool dry summer.
Taxonomically, there have been few changes in American species. A recent phylogenetic study by Nguyen et al., 2008 found that North American alliums are distinct from European species and those occurring in the California Floristic Province (CFP) are distinct from eastern American species. California holds a wide variety of species whose forms are distinctive in leaf morphology. Species related to Allium falcifolium form falcate leaves whereas species related to Allium jepsonii form a single leaf from which the inflorescence emerges on the side. Many CFP species have also adapted to a special type of soil called serpentine which is very high in minerals such as magnesium, making it toxic to many plants. Some Allium species are so adapted that they can only be found on serpentine soil in the wild.
American alliums from I-M are found on this wiki page.
Allium jepsonii is a Californian species that grows in the Sierra Nevada foothills in two different areas, one on serpentine in the north and the other on volcanic soils in the central foothills. It has a single, terete, rat-tail-like leaf, from which pops out a flower stem from a basal incision near the base, and a small head of white, lightly nerved flowers in July. Needs excellent drainage. The stems tend to recline, as shown in the image. The species is often found on serpentine. For a while it was listed as an endangered species and has now been delisted due to discoveries of new populations. Photos by Mark McDonough, Mary Sue Ittner and Nhu Nguyen at the Tilden Botanic Garden.
Allium lacunosum is a California species that occurs widely south of San Francisco. It has small white to pale pink flowers in close umbels. There are four varieties which are distinguished by measurement of plant parts and range. The photos below are of plants in cultivation. Photo 1 taken by Mary Sue Ittner is of an unknown variety. Photos 2-3 were taken by Nhu Nguyen of variety lacunosum.
Allium lacunosum var. lacunosum has leaves that are longer than the stem (10-20 cm). The flowers measure 7-9 mm. This variety is found along the coast and in the coast ranges. The photos below were taken by Nhu Nguyen from Ring Mountain where they occur on serpentine outcrops by the thousands. The petals fade to a rusty brown and are persistent as the seeds mature.
Allium lemmonii has a rather broad range in the western states. It is found on slopes made of mostly clay soil. It is a relative of Allium falcifolium where the leaves are flattened and somewhat falcate. Photo 1 shows the flower head, which is rather large, and photo 2 shows the habit. Photo 3 show plants that are just starting to push up the buds. Photos by Nhu Nguyen taken at the Tilden Botanic Garden.
Allium mannii - this is a Mexican species rare in cultivation. Surprisingly, many of the southwestern, Texan, and even Mexican onions are proving to be hardy in northern New England. This species is quite different than most other American onions, perhaps closed allied to A. plummerae from Arizona and New Mexico. Allium mannii has spread slowly via short rhizomes, and reliably puts forth upfacing "rounded star-cup" flowers in open clusters for several weeks in July. As the fresh white flowers mature, the central ovaries age from pink to orangish-brown. Photo by Mark McDonough.
Allium membranaceum grows in Northern California from 500 to 4500 ft (150 to 1350 m) and is most similar to Allium campanulatum than to any other species. It has white to pale pink flowers on an erect stem, flat leaves, and a very dainty appearance. Photos 1-3 were taken by Mary Sue Ittner. Photo 3 shows the bulbs on a 1 cm grid. Photos 3-6 were taken by Nhu Nguyen of the same clone.
Allium index - Allium flavum Relatives - American alliums A-B - American alliums C - American alliums D-F - American alliums G-H - American alliums N-R - American alliums S-Z - Big Ball alliums - Blue alliums - chives - Domed alliums - Drumstick alliums - Miscellaneous alliums A-E - Miscellaneous alliums F-M - Miscellaneous alliums N-R - Miscellaneous alliums S-Z - Rhizomatous alliums