Eriogonum umbellatum

Eriogonum umbellatum is a species of wild buckwheat known by the common name sulphurflower buckwheat, or simply sulphur flower. It is native to western North America from California to Colorado to central Canada, where it is abundant and found in many habitats. This is an extremely variable plant and hard to identify because individuals can look very different from one another. Also, there are a great many varieties. It may be a perennial herb forming a small clump with flowers to 10 centimeters tall, or a sprawling shrub approaching two meters high and wide. The leaves are usually woolly and low on the plant, and the flowers come in many colors from white to bright yellow to purple. Native American groups utilized parts of this plant for a number of medicinal uses.

Eriogonum umbellatum
Eriogonum umbellatum var. hypoleium
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Order:	Caryophyllales
Family:	Polygonaceae
Genus:	Eriogonum
Species:	E. umbellatum
Binomial name
Eriogonum umbellatum Torr.

It is a popular larval host, feeding the bramble hairstreak, desert green hairstreak, lupine blue, Mormon metalmark, Rocky Mountain dotted blue, Sheridan's hairstreak, Sonoran metalmark, and western green hairstreak.[1] Additionally, goats and domestic sheep feed on the plant.[2]

Varieties of this species include, but are not limited to:

• E. u. var. argus - often nearly hairless leaves and bright yellow flowers; limited to the Klamath Mountains
• E. u. var. dichrocephalum - found throughout much of the western United States
• E. u. var. furcosum - a low shrub native to the Sierra Nevada
• E. u. var. glaberrimum - (green buckwheat) - a nearly hairless, white-flowered species
• E. u. var. humistratum - (Mt. Eddy buckwheat) - a rare northern California endemic
• E. u. var. juniporinum - (juniper buckwheat) - an uncommon plant of eastern California and western Nevada
• E. u. var. subalpinum - (sulfur buckwheat) - similar to Eriogonum eriogonum but has wider and more spoon-shaped leaves
• E. u. var. torreyanum - (Donner Pass buckwheat) - known from fewer than 10 occurrences near the Donner Pass
• E. u. var. versicolor - bears pinkish-brown flowers with bright stripes

• 
  E. umbellatum var. humistratum (habit)
• 
  E. umbellatum var. humistratum (flowers)
• 
  E. umbellatum var. hypoleium (habit, William O. Douglas Wilderness)
• 
  E. umbellatum var. hypoleium (flowers)
• 
  E. umbellatum var. majus (flowers, Wenatchee Mountains)
• 
  E. umbellatum var. subaridum (flowers, Spring Mountains)