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Sidalcea oregana var. calva

Oregon checkermallow

Photo is of parent taxon

Kenwood Marsh checkerbloom

Habit Plants 0.9–1.2(–1.5) m, with thick, ± fleshy roots or rootstock.

decumbent-based, base often rooting, branched or not, solid, often hollow in age, 5–10 mm diam. near base, base usually bristly-hirsute, sometimes with minute stellate hairs, bristle hairs 1–1.5 mm, becoming glabrate distally.


stipules linear or lanceolate, 4–longer than pedicels, shorter than calyx.


1–2 mm.


bisexual or unisexual and pistillate, plants gynodioecious;

calyx 7.5 mm, accrescent, finely stellate-puberulent, sparsely, if at all, bristly;

petals dark rose-pink to pink-lavender, 10–15 mm;

staminal column 4–6 mm, hairy;

anthers white;

stigmas (6 or)7 or 8.


1.5–2.5 mm.


5–6 mm diam.;

mericarps (6 or)7 or 8, 3 mm, sparsely glandular-puberulent, smooth, mucro 0.5 mm.


= 20.

Sidalcea oregana var. calva

Sidalcea oregana subsp. valida

Phenology Flowering Jun–Sep.
Habitat Marshes
Elevation 100–200 m (300–700 ft)
from FNA
[BONAP county map]

Of conservation concern.

Subspecies valida is known from a small area and is threatened by grazing and marsh alteration. It is found in freshwater marshes near Kenwood, southern outer North Coast Ranges in Sonoma County. It has been listed as endangered in California and also federally. It is similar to subsp. hydrophila except in overall size, spike length, number of flowers, and indument patterns as well as range and habitat. The somewhat fleshy roots are a reflection of its marshy habitat; it is not closely related to the other fleshy-rooted Sidalcea species.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 6, p. 351.
Parent taxa Malvaceae > subfam. Malvoideae > Sidalcea > Sidalcea oregana
Sibling taxa
S. oregana subsp. eximia, S. oregana subsp. hydrophila, S. oregana subsp. oregana, S. oregana subsp. spicata, S. oregana subsp. valida
S. oregana subsp. eximia, S. oregana subsp. hydrophila, S. oregana subsp. oregana, S. oregana subsp. spicata
Synonyms S. valida, S. spicata subsp. valida
Name authority (Greene) C. L. Hitchcock: Perenn. Sp. Sidalcea, 67. (1957)
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