Eriogonums are attractive plants found abundantly in the Four Corners region, mostly in the semi-desert but also in the mountains. Flowers are often long lasting in showy clusters. Species are found flowering throughout the growing season, and many are late summer and fall flowering. Various Eriogonum species may be tall and lanky; matted; sprawling; bushy; herbaceous or woody; pink, white, or yellow flowering; annual, biennial, perennial, or monocarpic; and often in hot and dry environments.

     With about 230 species, the Eriogonum genus is the second largest North American endemic genus. Penstemon is the largest with 243 species. If we include genera found in North America but also found elsewhere, we would find two larger North American genera, Carex with 479 species and Astragalus with 379 species. The latter two genera are much larger if we look at their world-wide numbers: Carex has about 1,800 species and Astragalus tops the world charts with an amazing 3,200 species, almost double the next contestant, Bulbophyllum. On this website there are 16 Eriogonum species, placing it 4th behind Astragalus with 31 species, Erigeron with 28 species, and Penstemon with 22 species.

     Eriogonum range from east central Alaska south to central Mexico and from near-shore islands off the California and Baja California coasts to the Great Plains of central Canada south to central Mexico, the Appalachian Mountains of West Virginia and Virginia, and the coastal plains of the southeastern United States from the Carolinas to central Florida. (Most information taken from James Reveal's key to Polygonaceae.)

Click to read more about Eriogonum from James Reveal.
Click to read the Flora of North America treatment of Eriogonum.
Click to read about the Eriogonum Society.
Click to read Eriogonum in the Garden

     The Eriogonum genus was named by Andre Michaux (1746-1803) in his 1803, Flora Boreali-Americana. (Click the title to read.) "Erio" is Greek for "wool" and "gono" for "knee", referring to the woolly leaves and swollen joints of the type species.

    It is interesting to note that the eminent botanist and naturalist, Thomas Nuttall, who named a number of Eriogonum species in the early 1800s, predicted early in his study of the genus that when the West was thoroughly explored, Eriogonum would probably be found to be a large genus:

"Thus the genus Eriogonum, as yet peculiar to North America... may probably form a numerous genus, whenever the great plains of California, the Columbia, the Missouri, and the Arkansa shall be explored".

In this, as in most of Nuttall's botany, he was correct. Click to read Nuttall's "Observations on the Genus Eriogonum".

This is a native species.

Eriogonum umbellatum

Eriogonum umbellatum

Eriogonum umbellatum

Eriogonum umbellatum




Eriogonum umbellatum (Sulphur Flower)
Polygonaceae (Buckwheat Family)

Foothills, montane, subalpine. Meadows, openings. Spring, summer.
Above: Prater Ridge Trail, Mesa Verde National Park, June 24, 2017.
Left: Mesa Verde National Park, May 31, 2004, Mike and Mona's Five Springs Farm, July 14, 2010, and Mesa Verde National Park, September 26, 2010.

Sulfur Flower is an abundant, very bright addition to hot, dry meadows of foothills and mountains throughout the West. Its numerous, long-lasting flowers start as red-tinted buds, open brilliant yellow, and then dry to oranges and reds. Its small, vertical leaves form dense wide mats and change to reds in the fall. The young plants at top left will eventually merge and spread, forming a larger and larger mat.

Eriogonum umbellatum is, according to Flora of North America, "widespread and exceedingly variable...."  The discussion of the forty-one varieties of E. umbellatum takes up over eighteen pages in the FNA. Nine of the varieties occur in at least one of the Four Corners states. Only one variety, subaridum, occurs in New Mexico. The  forty-one varieties differ from one another in their bracts, in flower size and color, leaf blade hairiness and shape, the upright or spreading posture of the plant, etc.

The Four Corners region hosts three varieties: aureum, subaridum, and umbellatum, the latter being the most common. Varieties subaridum and umbellatum have leaves that are pubescent at least on the lower surface; variety aureum has glabrous leaves.

According to A Utah Flora and Colorado Flora, the primary difference between variety subaridum and variety umbellatum is that the former has a compound flower umbel; variety umbellatum has a simple umbel. However, THE Eriogonum expert, James Reveal, indicates that both varieties can have compound umbels. Reveal separates the two varieties primarily by their growth habit and hairiness:

Variety subaridum is a subshrub or shrub growing to over 24 inches tall and 36 inches wide;
Variety umbellatum is a spreading matted herb, not shrubby and growing to no more than 14 inches tall and 24 inches wide.

The aerial flowering stems of var. subaridum are erect, (0.5) 1–3 dm long, floccose or glabrous. Leaves are thinly floccose on both surfaces or glabrous and green adaxially.

The aerial flowering stems of var. umbellatum are erect, 1–2.5 (3) dm long, tomentose to floccose. Leaves are white- to gray-lanate abaxially, less so to floccose or glabrous and green adaxially.

John Torrey named Eriogonum umbellatum in 1828 from a specimen collected by Edwin James "Near the Rocky Mountains" in 1820.

"Umbellatum" refers to the umbel (umbrella-like) arrangement of the flowers.

Erigonum umbellatum

Eriogonum umbellatum

Eriogonum umbellatum

Eriogonum umbellatum (Sulphur Flower) 
Polygonaceae (Buckwheat Family)

Foothills, montane, subalpine. Meadows, openings. Spring, summer.
Mesa Verde National Park, June 3, 2004.

The third photograph at left best shows the small, green, leaf-like bracts that subtend the flower umbel  --  the upward spray of flower stems in the form of spokes similar to the spokes of an umbrella.

Eriogonum umbellatum

Eriogonum umbellatum

Eriogonum umbellatum (Sulfur Flower)
Polygonaceae (Buckwheat Family)

Foothills, montane, subalpine. Meadows, openings. Spring, summer.
Fish Creek Trail, August 9, 2005 and Lone Mesa State Park, August 15, 2008.

Fading flowers have subtle shades of orange, red, and yellow.

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Questionable presence

Eriogonum umbellatum
Range map for Eriogonum umbellatum

E. umbellatum var. aureum
Range map for E. umbellatum var. aureum

E. umbellatum var. subaridum
Range map for E. umbellatum var. subaridum

E. umbellatum var. umbellatum
Range map for E. umbellatum var. umbellatum