Aliso 4: 92. 1958 ,.
Plants 1–2.5 m. Stems erect, densely white soft-pubescent; spines at nodes absent or 1–3, 4–8 mm; prickles on internodes scattered, glandular and eglandular. Leaves: petiole 1–2 cm, copiously white-pilose; blade oblong to roundish, shallowly 5-lobed, cleft 1/4–1/3 to midrib, 2–3 cm, base truncate, surfaces soft-pubescent abaxially, subglabrous adaxially, lobes rounded, margins coarsely crenate-dentate, apex rounded to acute. Inflorescences pendent, solitary flowers or 2-flowered racemes, 2–4 cm, axis white-pilose. Pedicels not jointed, 6–8 mm, pilose; bracts broadly lanceolate, 2–3 mm, white-pilose. Flowers: hypanthium pinkish, narrowly tubular, 4–5 mm (1/2 as long as sepals), white-pilose, not glandular; sepals not overlapping, erect, pinkish, lanceolate, 9–10 mm; petals connivent, erect, white, oblong, inrolled, 4–6 mm; nectary disc not prominent; stamens 1.3 times as long as petals; filaments linear, 4–6 mm, glabrous; anthers white, lanceolate, somewhat sagittate, 3 mm, apex apiculate; ovary pilose, not glandular; styles connate nearly 3/4 their lengths, 9–11 mm, glabrous. Berries palatability not known, purple, subglobose, 7 mm, pilose-hairy with nonglandular spines.
Phenology: Flowering Nov–Jul.
Habitat: Ravines in pine forests
Elevation: 0-700 m
Ribes thacherianum is known only from Santa Cruz Island, Santa Barbara County. The indehiscent part of the anther is short and dark.