Sidalcea calycosa subsp. rhizomata
Madroño 56: 106. 2009.
Phenology: Flowering May–Jul(–Sep).
Habitat: Freshwater and salt marshes near coast
Elevation: 0–30 m
Of conservation concern.
Subspecies rhizomata is known from only a few marshes near the coast in Marin, Mendocino, and Sonoma counties; it is easily distinguished by its relatively large, connate, ciliate bracts and prostrate fleshy rhizomes with scattered leaves and relatively large stipules.