Roystonea is a genus of eleven species of large, monoecious palms in the family Arecaceae (order Arecales), collectively known as royal palms. Native to the Neotropics, these are among the most recognizable and widely cultivated palms of tropical and subtropical regions worldwide.
Royal palms are stately, single-stemmed trees with smooth, columnar trunks that are often swollen and bulging along portions of their length — a feature thought to reflect years of varying growing conditions. A distinctive green sheath called the crownshaft wraps the uppermost 1.4–2 m of the trunk. Pinnate leaves emerge from the crownshaft, with rachises ranging from 3.2 to 5.8 m long; the leaves are adapted to release easily in strong winds, a likely hurricane adaptation. Most species reach 15–20 m in height, though Roystonea oleracea can exceed 42 m. Flowers are small, white, and unisexual, borne in branched panicles beneath the crownshaft; fruits are oblong purple drupes 1–2 cm long.
The genus ranges from southern Florida south through Mexico, Central America, and into Venezuela and Colombia, with the greatest species diversity in Cuba (five native species) and Hispaniola and Jamaica (two each). Roystonea regia, the Cuban royal palm, is perhaps the best-known member and is the national tree of Cuba.
Within Arecaceae, Roystonea is placed in the subfamily Arecoideae and the monogeneric tribe Roystoneae. Its precise phylogenetic position within the subfamily remains uncertain; plastid DNA analyses have not resolved its placement. One species is known only from fossilized flowers preserved in Dominican amber.
Etymology
The genus name Roystonea honors Roy Stone (1836–1905), a U.S. Army engineer who worked in Puerto Rico following the Spanish–American War. The name is a Latinized derivation of his surname.
Distribution
Roystonea has a circum-Caribbean distribution, occurring naturally from southern Florida south through Mexico, Honduras, Nicaragua, Venezuela, and Colombia, and on Caribbean islands. Cuba holds the greatest diversity with five native species; Hispaniola and Jamaica each have two native species. The genus is also widely planted as an ornamental far beyond its native range, including in parts of North Africa.
Cultural Uses
Royal palms have long served both ornamental and practical purposes across the Caribbean. The growing tip (heart of palm) is harvested for use in salads. The seeds, which are rich in oil, have been used as a substitute for coffee and were historically fed to pigs in Cuba — the resulting pork was considered exceptionally flavorful and the lard of superior quality. Seed harvesting required skilled climbers using rope loops around the trunk. Today, royal palms are among the most widely planted ornamental trees of the tropics and subtropics.
Taxonomy Notes
Roystonea is placed in subfamily Arecoideae and the monogeneric tribe Roystoneae within Arecaceae. Its position within Arecoideae is unresolved: as of 2008, no molecular phylogenetic study had placed the genus with confidence, and a plastid DNA analysis left its position ambiguous. One species, known only from two fossilized flowers in Dominican amber, was described in 2002 and adds a paleobotanical dimension to the genus.
