Sidalcea hendersonii is a species of flowering plant in the mallow family known by the common name Henderson's checker-mallow.

Flowers are five-petaled and numerous, typically fifty or more per plant, forming in branched racemes atop stems.

[2] Sidalcea hendersonii needs wet soil so its range is limited to tidal marches and flats that experience inundation at low elevations.

[2] 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.

Outlying occurrences are found in Oregon and British Columbia with the majority of the global population in Washington state.