Bicolor Sulphur Flower, Sulphur Flower Buckwheat: Eriogonum umbellatum var. dichrocephalum (Synonyms: Eriogonum umbellatum ssp. aridum, Eriogonum umbellatum var. aridum)

Sulfur buckwheat is an attractive, but variable, perennial species. The plants when prostrate, may be as much as 60 cm wide. The stems lack leaves, but a whorl of leafy bracts may be found directly below the inflorescence. The leaves are mostly basal, with the blades oval or elliptical in shape with long, thin petioles, and fairly tomentose especially on the lower surfaces. The upper leaf surfaces are often greener. The leaves are generally more or less elliptic in shape and range from 1-4 cm long and about 5-20 mm wide. The flower stems range from 10-200 cm high.

The inflorescence is typically an open umbel or occasionally head-like at the ends of erect stems. Several leaf-like bracts subtend the inflorescence. The umbels are usually 2-10 rayed with individual rays from very short to 12 cm long. One involucre is usually found per ray. The pubescent to lanate involucres are conical to narrowly bell-shaped with linear-lanceolate to oblong lobes from 2-3 mm long. The 6-12 involucral lobes are commonly reflexed or spreading and nearly equal in length to the tube. Individual involucres are 20-40 flowered. The perianth is glabrous with lobes from 2.5-5 mm long that are typically creamy, or frequently a light to bright yellow as in the variety shown above. The yellow flowers may also be tinged with red. The fruits are glabrous and range from 2-5 mm long.

Sulfur buckwheat is a varied species, found with sagebrush in the lowlands, to exposed alpine ridges, on both rocky and sandy substrates.

A widespread species, sulfurflower is found from southern British Columbia, south along the eastern edge of the Cascades and Sierra Nevada Mts. to southern California, and eastward to the east side of the Rocky Mts.

This is a pretty wildflower of long bloom period, with interesting foliage which could be used successfully in rockeries or dry, natural garden, especially in the intermountain region. It will survive west of the Cascades, but needs good drainage and perhaps some protection from winter rains.

Sulfur-flower Buckwheat: Eriogonum umbellatum var. argus: Leaf blade margins often finely wavy. Inflorescence compound, often with alternate to whorled bracts near the middle. Individual rays are often branched again. The inflorescence is thinly tomentose. Perianth 3-8 mm, bright yellow. Often found on serpentine. Not found east of the Cascade Mountains. Found from southwest Oregon to the Klamath Region and high North Coast Range of northwestern California.

Golden Sulphur Flower, Great Basin Sulphur Buckwheat: Eriogonum umbellatum var. aureum (Synonyms: Eriogonum umbellatum var. intectum) - Primary rays of umbel simple, not branched or bracteate in the middle. Plants over 10 cm tall and the umbels open. Perianth yellow. Leaves glabrous on both surfaces with elliptic leaves. Found from southern Oregon and Idaho south to Nevada and Utah and east to Wyoming.

Bicolor Sulphur Flower, Sulphur Flower Buckwheat: Eriogonum umbellatum var. dichrocephalum (Synonyms: Eriogonum umbellatum ssp. aridum, Eriogonum umbellatum var. aridum) - The leaf blades are more or less elliptic and generally subglabrous below. The infloresecnce is simple and subglabrous. The perianth is 4-8 mm long and whitish to pale yellow in color, often conspciuously striped. Found on sand, gravel or rock in California in the Warner Mts and in the White and Inyo Mts. It is found north in the Great Basin to southeastern Oregon and east to Montana and Wyoming.

American Valley Sulphur Flower: Eriogonum umbellatum var. dumosum (Synonyms: Eriogonum umbellatum var. polyanthum, Eriogonum umbellatum var. speciosum) - Found west of the Cascade Mts. crest in Oregon.

Sulphur Buckwheat, Sulphur Flower Buckwheat: Eriogonum umbellatum var. ellipticum (Synonyms: Eriogonum ellipticum, Eriogonum stellatum, Eriogonum umbellatum var. chrysanthum, Eriogonum umbellatum var. croceum, Eriogonum umbellatum ssp. stellatum, Eriogonum umbellatum var. stellatum) - Primary rays of umbel compoundly branched up to 2-3 times. The umbellets are each usually subtended by a whorl of bracts. Underside of leaves tomentose. Found from southeastern Washington and northeastern Oregon south to California and east to central and southwestern Idaho.

Green Buckwheat, Sulphur Flower Buckwheat, Warner Mountains Sulphur Flower: Eriogonum umbellatum var. glaberrimum - Green Buckwheat- Inflorescence compound with primary rays of umbel with bracts but not compoundly branched. Leaves glabrous on both surfaces and with blades more or less oblanceolate in shape. The perianth is 4-7 mm long and whitish to cream in color. Found on sand or gravel in south-central Oregon and in the Warner Mts of northeastern California.

Goodman's Sulphur Flower: Eriogonum umbellatum var. goodmanii - Located west of the Cascade Mts. crest in the Siskiyou region of southwestern Oregon.

Haussknecht's Buckwheat, Haussknecht's Sulphur Flower, Sulfur Buckwheat: Eriogonum umbellatum var. haussknechtii (Synonyms: Eriogonum haussknechtii, Eriogonum montanum, Eriogonum umbellatum ssp. haussknechtii, Eriogonum umbellatum var. hausknechtii) - Primary rays of umbel simple, not branched or bracteate in the middle. Plants alpine or subalpine, prostrate and dwarf-like. The flower stems rarely to 10 cm high. Found in the Cascade Mts. from southern Washington to central Oregon.

Sulfur Buckwheat, Sulphur-flower Buckwheat: Eriogonum umbellatum var. hypoleium (Synonym: Eriogonum umbellatum ssp. hypoleium) - Primary rays of umbel simple, not branched or bracteate in the middle. Plants over 10 cm tall and the umbels open. Perianth yellow. Leaves glabrous on both surfaces with slightly tomentose margins and midrib. Leaves obovate in outline. Found in the Wenatchee Mts. and Okanogan region of north-central Washington.

Sulphur-flower Buckwheat: Eriogonum umbellatum var. majus (Synonyms: Eriogonum heracleoides var. subalpinum, Eriogonum subalpinum, Eriogonum umbellatum ssp. majus, Eriogonum umbellatum var. subalpinum) - Primary rays of umbel simple, not branched or bracteate in the middle. Plants over 10 cm tall and the umbels open. Leaves less densely tomentose. Perianth white, cream, or pale yellow. Plants of the foothills up to 9000' in the mountains. Found from southern British Columbia east to the Rocky Mts. of Montana and Colorado and south to northeastern Washington and the east slope of the Washington Casacades.Modoc

Sulphur Flower: Eriogonum umbellatum var. modocense (Synonym: Eriogonum umbellatum var. polyanthum) -

Nevada Buckwheat, Nevada Sulphur Flower: Eriogonum umbellatum var. nevadense: A subshrub with the leaf blades moreor less thinly tomentose below. The inflorescence is simple and thinly tomentose. The perianth is 4-7 mm long and yellow. Found in California on the east slope of the Sierra Nevada, in the northwestern Mohave Desert and in the Great Basin of southern Oregon and central Nevada.

Sandberg's Sulphur Flower: Eriogonum umbellatum var. sandbergii - A species found just east of Mt. Hood.

Sulphur-flower: Eriogonum umbellatum variety umbellatum: Primary rays of umbel simple, not branched or bracteate in the middle. Plants over 10 cm tall and the umbels open. Perianth yellow. Leaves tomentose below and sparsely tomentose to glabrous above. Found from British Columbia and Idaho east to the Rocky Mt. states.

Close-up photos of bicolor sulfur flower as seen at the East Rim Viewpoint, Steens Mountain, Harney County, Oregon.........September 1, 2011.

Examples of a form of bicolor sulfur flower with cream-colored flowers as seen along Forest Road #1647 in southeastern Logan Valley, Malheur National Forest..........June 26, 2011.

Eriogonum umbellatum (var. dicrocephalum), Steens Mountain summit in Harney County, Oregon..........September 1, 2011.

Bicolor sulphur flower with creamy flowers (left) with Piper's buckwheat (Eriogonum flavum var. piperi) with yellow flowers in the upper photo at right on the southern base of Bullrun Rock, Monument Rock Wilderness......July 9, 2023.

Bicolor sulphur flower blooming at the head of Kiger Gorge, Steens Mountain, Harney County, Oregon........August 31, 2011.

Bicolor sulphur flower blooming at a pass along the trail between High Lake and Slide Lake, Strawberry Mountain Wilderness..........July 17, 2013.

The photo at upper left shows bicolor sulphur flower blooming along Road 1647 in southern Logan Valley, Grant County, Oregon..........May 30, 2014. The other 3 photos are from the Canyon Mountain Trail #218, Strawberry Mountain Wilderness.........May 29, 2014.

Bicolor sulphur flower as seen along FS Road #38-200 several miles southeast of Spanish Peak, Ochoco National Forest..........June 14, 2015.

Bicolor sulfur flower as seen at left in a roadside ditch along Forest Service Road #16 near Big Creek in Logan Valley, Malheur National Forest........August 20, 2011. The photo at right shows bicolor sulfur flower as seen atop East Point at the east end of the Mount Pisgah ridgeline, Ochoco National Forest........July 14, 2017.

Late season bicolor sulfur flower as seen left on a rock outcrop along the South Loop Road about one mile west of the East Rim Viewpoint, Steens Mountain..........September 20, 2015. The photo at right shows the colorful early fall form of bicolor sulfur flower as seen along a jeep road up the east face of Spanish Peak, Ochoco National Forest..........September 25, 2016.

Bicolor sulfur flower as seen atop Spanish Peak, Ochoco National Forest......June 17, 2019.