''Sericocarpus rigidus'' is a species of flowering plant in the family

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

known by the common name Columbian whitetop aster. It is native to the

Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though ...

of North America, where it is known from southern

Vancouver Island Vancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian Provinces and territories of Canada, province of British Columbia. The island is in length, in width at its widest point, and in total area, while are o ...

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

south along the coast to

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered on ...

and

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

.''Sericocarpus rigidus''.
The Nature Conservancy.''Sericocarpus rigidus''.
Center for Plant Conservation. This

rhizomatous In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...

perennial herb grows up to about 37 centimeters tall. Leaves along the stem are somewhat oval in shape and up to 6 centimeters long. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

has clusters of

flower heads A pseudanthium (Greek for "false flower"; ) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, compos ...

each up to about a centimeter long. Each contains white or off-white disc florets and usually a few white ray florets.''Sericocarpus rigidus''.
Flora of North America.''Sericocarpus rigidus''.
Washington Burke Museum. This species grows in

grassland A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...

habitat which is generally dominated by

Idaho fescue ''Festuca idahoensis'' is a species of grass known by the common names Idaho fescue and blue bunchgrass. It is native to western North America, where it is widespread and common. It can be found in many ecosystems, from shady forests to open plai ...

(''Festuca idahoensis''). It grows in gravelly soils originating from

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ablation over many years, often Century, centuries. It acquires dis ...

activity in the northern part of its range, and clay soils farther south. The soils are moist most of the year but dry in the summer. Associated species include

snowberry ''Symphoricarpos'', commonly known as the snowberry, waxberry, or ghostberry, is a small genus of about 15 species of deciduous shrubs in the honeysuckle family, Caprifoliaceae. With the exception of the Chinese coralberry, '' S. sinensis'', whi ...

(''Symphoricarpos albus''),

serviceberry ''Amelanchier'' ( ), also known as shadbush, shadwood or shadblow, serviceberry or sarvisberry (or just sarvis), juneberry, saskatoon, sugarplum, wild-plum or chuckley pear,A Digital Flora of Newfoundland and Labrador Vascular Plants/ref> is a g ...

(''Amelanchier alnifolia''),

Oregon sunshine ''Eriophyllum lanatum'', with the common names common woolly sunflower, Oregon sunshine and golden yarrow, is a common, widespread, North American plant in the family Asteraceae.Sierra Nevada Wildflowers, Karen Wiese, 2nd Ed. 2013, p. 116 Descri ...

(''Eriophyllum lanatum'') and early blue violet (''Viola adunca''). Much of the habitat is also covered with

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived there ...

such as Scot's broom (''Cytisus scoparius'') and yellow hairgrass (''Aira praecox''). The invasion of the habitat by introduced species is a threat to this plant. Other threats include loss of habitat to development, off-road vehicles, military activity, and

fire suppression Wildfire suppression is a range of firefighting tactics used to suppress wildfires. Firefighting efforts in wild land areas require different techniques, equipment, and training from the more familiar structure fire fighting found in populated a ...

References

{{Taxonbar, from=Q7454736 Astereae Flora of British Columbia Flora of Oregon Flora of Washington (state)