Oemleria Reichenb. (1841), the oso berry, in the family Rosaceae subfamily Prunoideae, contains 1 species, O. cerasiformis (Hook. & Arn.) Landon in western North America. It is often called Osmaronia E. Greene, or Nuttallia Torr. & Gray.
Description Small trees to 5m, or suckering shrubs, without thorns. The leaves are alternate, deciduous, and oblong or oblanceolate. The flowers are small, white, in hanging spikes, sometimes bisexual, but usually with males and females on different plants, produced in early spring, and almond-scented. Sepals 5, joined at the base; petals 5, equal. Male flowers with 15 stamens in 3 series, and with obovate petals 5–6mm long; female flowers with superior ovary, shorter, narrower petals, abortive stamens, and 5 carpels each with 1 ovule and style. Pollination is by insects. The fruits are 1–5 drupes, usually only 2 developing, black, glaucous, and bitter, with hard stones.
Key Recognition Features The narrow leaves and hanging spikes of small, white flowers.
Evolution and Relationships An isolated genus, close to Prunus, but differing in having 5 carpels, and 1 or 2 fruits from a single flower.
Ecology and Geography In chaparral and open places in the forest in California, from Santa Barbara County northwards to British Columbia in the Coast Ranges and the northwestern Sierra Nevada.
Comment In cultivation a modest shrub, grown for its very early flowering and almond scent.