Shrubs, usually erect, 0.1-50 dm, rhizomatous, (twigs of previous season verrucose, perennating buds dimorphic). Leaves usually deciduous, rarely persistent, (abaxial surface hairy or glabrous, adaxial surface usually glabrous). Inflorescences corymbs, terminal on axillary shoots from buds of previous season. Pedicels articulated with calyx tube. Flowers: sepals 5; petals 5, connate for nearly their entire lengths, corolla urceolate to cylindric; stamens 10, included; anthers without awns, tubules 2-4 mm, with terminal pores. Berries pseudo 10-locular. Seeds (4-)10-25(-40). 2n = 24, 48, 72.

Species 9 (9 in the flora): North America.

Section Cyanococcus contains populations that are all homoploids, regardless of species, and are interfertile; naturally occurring hybrids have been described (S. P. Vander Kloet 1988 and references therein). The blueberries are endemic to North America; large-scale plantings elsewhere have resulted in the establishment of adventive populations.

SELECTED REFERENCES Bruederle, L. P. and N. Vorsa. 1994. Genetic differentiation of diploid blueberry, Vaccinium sect. Cyanococcus (Ericaceae). Syst. Bot. 19: 337-349. Qu, L., J. F. Hancock, and J. H. Whallon. 1998. Evolution in an autopolyploid group displaying predominantly bivalent pairing at meiosis: Genomic similarity of diploid Vaccinium darrowii and autotetraploid V. corymbosum (Ericaceae). Amer. J. Bot. 85: 698-703. Vander Kloet, S. P. 1976. Nomenclature, taxonomy, and biosystematics of Vaccinium section Cyanococcus (the blueberries) in North America: 1. Natural barriers to gene exchange between Vaccinium angustifolium Ait. and Vaccinium corymbosum L. Rhodora 78: 503-515.