''Dimeresia'' is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus in the sunflower family containing the single species ''Dimeresia howellii'', known by the common name doublet.Calflora: ''Dimeresia howellii''
/ref>

Distribution

This uncommon plant is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to an area of the

Great Basin The Great Basin () is the largest area of contiguous endorheic watersheds, those with no outlets to the ocean, in North America. It spans nearly all of Nevada, much of Utah, and portions of California, Idaho, Oregon, Wyoming, and Baja Californi ...

region in the western United States, in northeastern

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

, southeastern

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

, southwestern

Idaho Idaho ( ) is a landlocked U.S. state, state in the Pacific Northwest and Mountain states, Mountain West subregions of the Western United States. It borders Montana and Wyoming to the east, Nevada and Utah to the south, and Washington (state), ...

, and northwestern

Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...

.Jepson eFlora: ''Dimeresia howellii''
/ref>Biota of North America Program 2013 county distribution map
/ref> It grows in dry volcanic soils, primarily on the Modoc Plateau volcanic plain, at elevations of .

Description

''Dimeresia howellii'' is a very tiny annual flowering plant rarely exceeding 4 centimeters in height or width. It forms a small tuft on the ground with several oval-shaped leaves, and is cobwebby at base and glandular above. The inflorescence has tiny white to purple bell-shaped flowers each a few millimeters long. The flowering period is May to August.

References

External links

Calflora Database: ''Dimeresia howellii'' (Doublet)

USDA Plants Profile for ''Dimeresia howellii'' (doublet)

Jepson Manual eFlora (TJM2) treatment of ''Dimeresia howellii''

UC CalPhotos gallery of ''Dimeresia howellii'' (doublet)
* Chaenactideae Flora of California Flora of Nevada Flora of Oregon Flora of the Great Basin Endemic flora of the United States ~ Monotypic Asteraceae genera Flora without expected TNC conservation status {{Asteroideae-stub