Brunfelsia densifolia, commonly known as Serpentine Hill raintree, is a rare shrub native to Puerto Rico, where it is found in serpentine soil habitats in the island’s subtropical dry and moist forests. Growing up to 10 feet tall, it is distinguished by its exceptionally long floral tube—often reaching 6–10 inches—which supports a small, bright yellow, five-lobed corolla. The flowers bloom primarily in late winter and spring, producing a sweet fragrance that attracts specialized long-tongued pollinators, particularly hawkmoths. This species is adapted to nutrient-poor, heavy-metal-rich serpentine soils, making it a specialized and ecologically significant component of its native flora. Its evergreen leaves are narrow, leathery, and arranged alternately, contributing to its tolerance of intense sun and drought conditions. Due to habitat loss and its restricted distribution, Brunfelsia densifolia is considered endangered in the wild. Like other members of the genus, all plant parts contain toxic alkaloids and should not be ingested. Photographed in Florida.