THE TAXONOMY, ECOLOGY, AND HORTICULTURE OF VACCINIUM SECTION HERPOTHAMNUS (ERICACEAE) (CREEPING BLUEBERRIES)

Vaccinium sect. Herpothamnus is revised based on investigation of the morphology, anatomy, reproductive biology, artificial hybridization, ecology, and phytosociology. It is treated as monotypic, consisting of V. crassifolium with two polymorphic subspecies, subsp. crassifolium and subsp. sempervirens (V. sempervirens). Comparison with other Vacciniums indicates possible ancestral relationships with South American species from the Guayana Highland (V. puberulum and V. roraimense in sect. Neurodesia).; Vegetational and environmental data were collected throughout the geographical range of sect. Herpothamnus and investigated using ordination by detrended correspondence analysis (DECORANA), numerical classification by two-way indicator species analysis (TWINSPAN), and multiple regression analysis. Stands with subsp. sempervirens have vegetational and environmental characteristics that fit within the range of those stands with subsp. crassifolium. Ranking of plant associates and environmental analysis indicates a strong association with Pinus palustris and adaptation to a frequent fire regime. Models developed from multiple linear regressions of ordination scores against environmental variables indicate that complex soil factors, especially those affected by fire frequency, are associated with variation in plant community composition across the range of sect. Herpothamnus.; Investigation of the taxonomic history of sect. Herpothamnus revealed a previous use of V. sempervirens by Rafinesque. That use is established as a nomen nuden and a synonym for V. ovatum and does not affect the later use of V. sempervirens by Rayner and Henderson.; Horticultural evaluations of clones of sect. Herpothamnus, especially those in common garden-selection plots, indicate that the long-recognized but undeveloped ornamental potential may yield low-maintenance, evergreen groundcovers tolerant of well-drained exposed sites subject to heat and drought. Vaccinium crassifolium subsp. crassifolium 'Wells Delight' and V. crassifolium subsp. sempervirens 'Bloodstone' were released in 1984 and are the first named cultivars of creeping blueberry.