''Sidalcea hendersonii'' is a species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

in the

mallow family Malvaceae, or the mallows, is a family of flowering plants estimated to contain 244 genera with 4225 known species. Well-known members of economic importance include okra, cotton, cacao and durian. There are also some genera containing familiar o ...

known by the common name Henderson's checker-mallow. 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 ...

region of

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. It is named for Oregon botanist Dr. Louis Forniquet Henderson (1853–1942), who was a professor at the University of Oregon.

Distribution

Occurs in coastal areas spanning from southern

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 ...

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 ...

and mainland

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, ...

. Its range follows the coastline; it grows in

tidal marsh A tidal marsh (also known as a type of "tidal wetland") is a marsh found along rivers, coasts and estuaries which floods and drains by the tidal movement of the adjacent estuary, sea or ocean. Tidal marshes are commonly zoned into lower marshes ( ...

es and

meadow A meadow ( ) is an open habitat, or field, vegetated by grasses, herbs, and other non-woody plants. Trees or shrubs may sparsely populate meadows, as long as these areas maintain an open character. Meadows may be naturally occurring or artifi ...

s. Extremely rare in Oregon, uncommon in

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 rare in British Columbia.

Description

''Sidalcea hendersonii'' is a taprooted perennial herb that grows from thick and stubby rhizomes. It has a basal rosette of toothed basal leaves. Stems are erect and hollow, and typically tinged purple. Flowers are five-petaled and numerous, typically fifty or more per plant, forming in branched

raceme A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the s ...

s atop stems. After flowering, seed fruits are developed. They are capsular, with 5 to 10 chambers, each containing one seed.

Ecology

''Sidalcea hendersonii'' needs wet soil so its range is limited to tidal marches and flats that experience inundation at low elevations. Its range is scattered, ranging from Southern British Columbia to the mouth of the Umpqua River. This plant is considered at risk by NatureServe due to the following reasons: "This species is limited to the coastal tideland and marshes along the Pacific Northwest from as far south as Douglas County, Oregon to Vancouver Island, British Columbia, Canada. A recent collection in Alaska suggests a range extension. Outlying occurrences are found in Oregon and British Columbia with the majority of the global population in Washington state. Total estimated occurrences are between 21–100 with plant numbers estimated as over 3000+ but probably more like 10,000+. There do not appear to be any imminent threats to this species."

References

hendersonii Flora of Oregon Flora of British Columbia Flora of Washington (state) Taxa named by Sereno Watson {{Malveae-stub