6. Malacothamnus densiflorus (S. Watson) Greene, Leafl. Bot. Observ. Crit. 1: 208. 1906.
Dense-flowered or yellowstem bushmallow Dense-flowered or yellowstem bushmallow
Malvastrum densiflorum S. Watson, Proc. Amer. Acad. Arts 17: 368. 1882; Malacothamnus densiflorus var. viscidus (Abrams) Kearney; Malvastrum densiflorum var. viscidum (Abrams) Estes; M. viscidum Abrams; Sphaeralcea densiflora (S. Watson) Jepson; S. densiflora var. viscida (Abrams) Jepson
Shrubs, 1–2 m, branches slender, indument tawny, sparse to moderately dense, stellate hairs sessile or subsessile, usually overlain by 1–2–few-armed, bristly hairs to 3 mm, glandular hairs often abundant. Leaf blades ovate, broadly ovate, or round, unlobed or 3- or 5-lobed, 3–6 cm, often leathery, surfaces: abaxial sometimes glossy green, adaxial densely tawny-hairy, basal sinus open, not overlapping. Inflorescences interrupted, spicate, flower clusters sessile, glomerate, 10+-flowered; involucellar bractlets awl-shaped to filiform, 5–15 × 1 mm, 2/3–1 1/2 times calyx length. Flowers: calyx angled in bud, 6–14 mm, lobes triangular to ovate, 4–11 × 2.3–3.5(–5) mm, slightly less to slightly more than 2 times as long as wide, equaling to 3 times tube length, apex acute to acuminate, sparsely bristly-hairy, hairs 1–few-armed, to 3 mm; petals pale pink, 1–2 cm. Mericarps 2.4–3.2 mm. 2n = 34.
Flowering Mar–Jun(Sep–Oct). Chaparral, coastal sage scrub ecotone; (100–)300–1100 m; Calif.; Mexico (Baja California).
Malacothamnus densiflorus occurs in the southern Coast Ranges. Plants with relatively short involucellar bractlets and calyx measurements in the lower range have been recognized as var. viscidus; intergradation with more typical forms is complete. Malacothamnus densiflorus intergrades with M. fasciculatus at lower elevations of the coastal Peninsula Ranges in San Diego County.