Roystonea

Roystonea (Royal Palm) is a genus of 10 species of monoecious palms, native to tropical regions of Florida, the Caribbean, and the adjacent coasts of Central and South America. Named for Roy Stone, a U.S. Army engineer, the genus contains some of the most recognizable and commonly cultivated palms (R. regia) in tropical and subtropical regions.

Description

Roystonea species are single-stemmed trees, average in height to among the world's tallest. Growing from 10-30 m tall, the trunks are white, or nearly so, often bulging either at the base or the central portion, depending on the species. The leaves are pinnate, 3-7 m long with numerous (about 100) pinnae up to 1 m long and 2-4 cm broad; the leaves also have a distinctive green basal sheath (crownshaft) extending 2-5 m down the trunk. These plants have the ability to easily release their leaves in strong winds, a supposed adaption serving to prevent toppling during hurricanes. Inflorescences occur beneath the crownshaft, emerging from a narrow, horn-shaped bract. The flowers on the branched panicles are usually white, unisexual, and contain both sexes. The fruit is an oblong or globose drupe 1-2 cm long and deep purple when ripe. Some species so closely resemble one another that scientific differentiation is by inflorescence detail; flower size, color, etc.Species

Roystonea altissima (Mill.) H.E.Moore
Roystonea borinquena O.F.Cook (syn. R. hispaniolana) - Hispaniola or Puerto Rico Royal Palm
Roystonea dunlapiana P.H.Allen
Roystonea lenis León
Roystonea maisiana (L.H.Bailey) Zona
Roystonea oleracea (Jacq.) O.F.Cook (syn. R. venezuelana) - Trinidad or Venezuela Royal Palm
Roystonea princeps (Becc.) Burret - Jamaican Royal Palm
Roystonea regia (Kunth) O.F.Cook (syn. R. elata, R. floridana) - Florida or Cuban Royal Palm
Roystonea stellata León
Roystonea violacea León

Cultivation and uses

Royal palms are widely planted for decorative purposes throughout their native region, and elsewhere in the tropics and subtropics. They are considered by many to be the most beautiful palm in the world.

While royal palms are considered a "tropical" palm, they do grow in favored microclimates in central Florida, e.g. some areas around Tampa Bay and Cape Canaveral. They also will grow - albeit slowly - in favored microclimates in southern California, southern Arizona and the extreme southern Texas barrier islands near the Gulf of Mexico. Royals are being increasingly planted on Galveston Island where they do very well and as far north as Houston where south of Interstate-10 you are beginning to see individuals 20-30 feet tall, unthinkable just 15 years ago.

Royal palms are rather intolerant of cold weather. The foliage will show cold damage at 31°F (-1°C) and the palm will defoliate at 29°F (-2°C). Royal Palms may be killed by temperatures of 25°F (-4°C). That said, seemingly "dead" Royal Palms may occasionally "return to life" after severe freezes in the low 20°F range (-5 or -6°C), but there is usually a trunk constriction that marks the event.

Royal palms are very fond of water and thrive on supplemental irrigation. They also do better in a soil with lots of humus.

Because their native location is in "hurricane alley", royal palms have adapted to the high winds by easily shedding their leaves. This leaves a bare trunk that more likely to survive a severe storm than a trunk with a full set of leaves. The palms quickly renew their foliage after such an event. On the island of Hispaniola, royal palms are trees favored by Palmchats for feeding, roosting and nesting.

The name "Royal Palm" is widely used in Florida for the name of streets, real estate developments, and the village of Royal Palm Beach.