Angelonia is a genus of about 30 species of flowering plants in the family Plantaginaceae (order Lamiales), native to the Americas from Mexico south to Argentina. Members of the genus are herbaceous perennials or subshrubs, characterized by snapdragon-like two-lipped flowers that are typically violet, purple, pink, or white. The genus is most diverse in north-eastern Brazil, where the majority of species occupy the Caatinga — a seasonally dry tropical forest adapted to semi-arid conditions.
A distinctive feature of Angelonia flowers is the presence of oil-secreting hairs inside the corolla. These structures form a mutualistic relationship with oil-collecting bees, particularly species of the genus Centris, which harvest the floral oils as larval provisions rather than nectar. This specialized pollination syndrome is rare among flowering plants and represents an evolutionary adaptation to the genus's semi-arid habitats.
Several species are cultivated as ornamental garden plants, valued for their prolific bloom and heat tolerance. Garden varieties are predominantly cultivars of Angelonia angustifolia, sometimes sold under the common name "summer snapdragon." These cultivars require warm temperatures and full sun, making them popular bedding plants in tropical and subtropical gardens.
Distribution
Angelonia ranges from Mexico south through Central America to Argentina. The genus is most concentrated in north-eastern Brazil, where the majority of species inhabit the Caatinga, a seasonally dry tropical forest biome characterized by semi-arid conditions.
Ecology
Flowers of Angelonia are specialized for oil-bee pollination: hairs inside the inner corolla produce oils collected by bees of the genus Centris. These bees use floral oils rather than nectar as larval food, making Angelonia dependent on this specialized guild of pollinators.
Cultivation
Garden cultivars of Angelonia, commonly called summer snapdragons, are predominantly derived from Angelonia angustifolia. They are grown as ornamental bedding plants for their long-lasting, snapdragon-like flowers in shades of violet, purple, pink, and white. They require full sun and warm temperatures and perform best in tropical to warm-temperate climates.
