Yellowstone Sulphur Flower

Yellow flowers of the Yellowstone sulphur flower.
Yellowstone sulphur flower wild buckwheat is only found in Yellowstone National Park.



Approximately 250 species of wild buckwheat are found in the world, with most of the species occurring in arid regions of the western United States. The group has undergone rapid evolution, leading to numerous closely related taxa. The sulfur buckwheats (Eriogonum umbellatum), of which there are 41 recognized varieties in the West, exemplify this rapid speciation. Several varieties of sulfur buckwheat live in the park, but the variety endemic to the park, Yellowstone sulphur flower (Eriogonum umbellatum var. cladophorum), in only found in the Firehole River drainage.


Yellowstone sulphur flower differs from the more common varieties with its bright yellow flowers and very hairy, somewhat gray looking leaves. The other bright yellow buckwheat in the area, Piper’s wild buckwheat (Eriogonum flavum var. piperi), blooms early in the summer, well before Yellowstone sulphurflower wild buckwheat, and on close examination the flowers are hairy on the exterior.

The close relative of Yellowstone sulphur flower has creamy yellow flowers without hairs, greenish leaves, and blooms before Yellowstone sulfur flower. Even though these two taxa are considered members of the same species, there has been no sign of interbreeding or hybridization. Growing on mildly influenced geothermal ground, this plant community includes several species that are more commonly encountered at lower elevations or as components of the Great Basin flora. Superficially, these areas in the vicinity of the park’s geyser basins look relatively barren, but the plant species representing different areas of the West form a unique plant community that can be found nowhere else.


Yellowstone sulfur flower is adapted to survive on barren, slightly geothermally influenced open areas. It apparently does not tolerate any shading, so it is a conspicuous component of relatively dry plant communities adjacent to the park’s thermal areas. The geographic range of this variety is highly restricted, having been found only from the Upper, Midway, and Lower geyser basins to the vicinity of Madison Junction. Adaptation to life in a geothermal setting means that this taxon has to be able to move with changes in the geothermal system. Yellowstone sulfur buckwheat is capable of recolonizing disturbed areas, as demonstrated by its presence near the Old Faithful Inn and Visitor Education Center, and other locations in the Upper Geyser Basin.

Alpine scene showing trees, grasses, and distant mountains.

Vegetation & Resources Management Branch

Park employees who inventory, monitor, manage, and research the vast array of plant communities in the park.

Whitebark pine growing on the summit of Mount Washburn.


Yellowstone's plants include species typical of the Rocky Mountains, the Great Plains, and the Intermountain region.



Whipple, J.J. 2012. Endemic plants of Yellowstone. Yellowstone Science. 20(1).

Tercek, M.T., T.S. Al-Niemi, and R.G. Stout. 2008. Plants exposed to high levels of carbon dioxide in Yellowstone National Park: A glimpse into the future? Yellowstone Science 16(1).

Whipple, J. 2004. The YS interview: Park botanist Jennifer Whipple and Yellowstone’s herbarium (interview) In Yellowstone Science 12(4).

Last updated: August 17, 2017

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