American Alliums S-Z

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 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 mostly distinct from eastern American species. California holds a wide variety of species whose forms are distinctive in leaf and bulb coat 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 S-Z are found on this wiki page.


American alliums A-B - American alliums C - American alliums D-F - American alliums G-H - American alliums I-M - American alliums N-R


Allium sp. Seeds of this undetermined species was collected in Chiapas, Mexico. It is a nice little plant that grows and blooms well in a 10 cm (4 inch) pot. It is a summer grower and needs a dry winter dormancy. It takes 3 years to flower this plant from seeds.

Allium sp. Chiapas, Nhu NguyenAllium sp. Chiapas, Nhu Nguyen

Allium stellatum Ker-Gawler is distributed from central Canada through the central part of the United States. It is commonly known as "prairie onion". It blooms from August into October with 2 to 3 inch (5-7.6 cm) heads of whitish to lavender florets. It is native to rocky soils and grows in clumps of narrow tubular foliage 30 to 70 cm (1 to 2 feet) tall. Photo from Steve Evans of plant flowering in Oklahoma September 2018. He notes that he has never seen it much more than about 1 foot (30 cm) tall.

Allium stellatum, Steve Evans


Allium unifolium is found in moist grasslands from 16 to 720 m in the Coast Ranges of California into Oregon. It flowers from May to June. It is one of the most commonly grown Californian species as a landscape bulb and multiplies rapidly, partly because new bulbs are produced on lateral rhizomes from the outside of the previous bulb. Seeds are very viable and they spread throughout botanical gardens where they are planted. In spite of going by the common name, one leaf onion, this species has 2 to 3 flattish leaves and a many flowered umbel of pink flowers with pale pink filaments and deeper pink anthers. The first two pictures taken by Bob Rutemoeller show it in habitat on the Sonoma coast and a close-up too. The third and fourth were taken by Nhu Nguyen and the fifth by Michael Mace.

Allium unifolium habitat, Bob RutemoellerAllium unifolium, Bob RutemoellerAllium unifolium, Nhu NguyenAllium unifolium, Nhu NguyenAllium unifolium, Michael Mace

Allium index - Allium flavum Relatives - American alliums A-B - American alliums C - American alliums D-F - American alliums G-H - American alliums I-M - American alliums N-R - 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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Page last modified on August 09, 2015, at 07:44 AM