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 phylogentic 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 N-R are found on this wiki page. American alliums A-C – American alliums D-H – American alliums I-M – American alliums S-Z
Allium perdulce - a gem of a species, from the American plains and prairies, and extending southwards into Texas. The flowers are intensely fragrant like cloves (dianthus), so sweet and spicy that it'll force you onto your belly to take frequent whiffs. It's one of the earliest blooming species, with rich pink, flared urn-shaped flowers on mere 4"-6" (10-15 cm) stems. It's exceedingly slow to increase for me (usually goes the other way!) and never sets viable seed in my garden. To be coveted. Photos by Mark McDonough and a line drawing as well.
Allium platycaule - is a western American allium from California, Oregon & Nevada. They occur on rocky or sandy slopes. The foliage is broad, gray, and sickle-shaped and arching sideways (falcate), and the large fuzzy globes of pink flowers only a few inches above the ground create a memorable sight. In the first photo, two bloom heads of the darker red-purple Allium falcifolium can be seen. First two photos by Mark McDonough, last photo by Nhu Nguyen.
Allium plummerae - one of my absolute favorites onions. It has a very limited range in Arizona and New Mexico, found at high elevation in marshes and alongside streams. Accordingly it prefers good garden soil and adequate irrigation. Upright tufts of strongly keeled (almost three-sided) grayish foliage, and showy flat clusters of wide-open upright stars. The flowers are pure white, with creamy yellow ovaries that age a tawny orangish color. Very reliable, non-invasive, clump-forming species, blooming in July-August. Photo by Mark McDonough.
Allium praecox is found in shaded grassy slopes in southwestern California. Photo by Mary Sue Ittner
Allium index – American alliums A-C – American alliums D-H – American alliums I-M – American alliums S-Z – Allium flavum Relatives – Allium hybrids – 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
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