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Roystonea regia, commonly known as the Cuban royal palm, Florida royal palm, or simply the royal palm is a species of palm which is native to South Florida, Mexico and part of Central America and the northern Caribbean. Although it ranged into central Florida in the eighteenth century, for some unknown reason in modern times it is only known from tropical parts of south Florida. A large and attractive palm, it has been planted throughout the tropics and subtropics as an ornamental tree. Although it is sometimes called R. elata, the name R. regia is preferred, as it is now a conserved name.
Although it is best known as an ornamental, R. regia is also used as a source of thatch and construction timber, and the fruit are eaten by birds, bats, and livestock. R. Regia is the national tree of Cuba.
Roystonea regia is a large palm which reaches a height of 20 – 30 metres (66 – 98 ft) tall, (with heights up to 34.5 m (113.2 ft) reported) and a stem diameter of about 47 centimetres (19 in). (Connor reports a maximum stem diameter of 61 cm (24 in).) The trunk is stout, very smooth and grey-white in colour. Trees have about 15 leaves which can be up to 4 m (13 ft) long. The stem is self-cleaning and old leaves will generally fall off by themselves, usually one each month, leaving a distinctive white scar that fades over time. The distance between two scars is a good indicator of the speed of growth of the plant at various stages with large gaps denoting fast growth, usually early in life.
The flowers are white with pinkish anthers. The fruit are spheroid to ellipsoid in shape, 8.9 – 15 millimetres (0.35 – 0.59 in) long and 7 – 10.9 mm (0.28 – 0.43 in) wide. They are green when immature, turning red and eventually purplish-black as they mature.
Root nodules containing Rhizobium bacteria have been found on R. regia trees in India. The presence of rhizobia-containing root nodules is usually associated with nitrogen fixation in legumes; this was the first record of root nodules in a monocotyledonous tree. Further evidence of nitrogen fixation was provided by the presence of nitrogenase (an enzyme used in nitrogen fixation) and leghaemoglobin, a compound which allows nitrogenase to function by reducing the oxygen concentration in the root nodule. In addition to evidence of nitrogen fixation, the nodules were also found to be producing IAA, an important plant hormone.
Cultivation and Growth
Roystonea regia is propagated easily by seed. Planting the whole fruits in well watered alluvial or clayey loams usually produces quick germination within three to five weeks. The seedlings are quite hardy and can be transplanted directly to soil within six months.
Young seedlings exhibit slow growth till they attain a height of about 1 metre and this is the height at which most nurseries sell specimens. Thereafter, the growth rate is one of the fastest amongst palms and trunk growth of 25-30 feet in 8-10 years is common with exceptionally vigourous specimens reaching 40 feet although this rate slows considerably after approximately 15 years.
The characteristic trunk may vary in diameter from 1 to 4 feet depending on the vigour of the specimen (closely planted seedlings demonstrate dominance with one 'dominant' seedling usually showing the fastest growth and the stoutest trunk).
Roystonea regia requires very little maintainence once it is firmly established and the phase of vigorous growth has started (usually characterised by creation of one frond a month). Young specimens exhibit dense root penetration in the surrounding area and these may need to be trimmed occassionally, especially if it is hindering the growth of nearby shrubs.
Roystonea is placed in the subfamily Arecoideae and the tribe Roystoneae. The placement Roystonea within the Arecoideae is uncertain; a phylogeny based on plastid DNA failed to resolve the position of the genus within the Arecoideae. As of 2008, there appear to be no molecular phylogenetic studies of Roystonea and the relationship between R. regia and the rest of the genus is uncertain.
The species was first described by American naturalist William Bartram in 1791 as Palma elata based on trees growing in central Florida. In 1816 German botanist Carl Sigismund Kunth described the species Oreodoxa regia based on collections made by Alexander von Humboldt and Aimé Bonpland in Cuba. In 1825 German botanist Curt Polycarp Joachim Sprengel moved it to the genus Oenocarpus and renamed it O. regius.
The genus Oreodoxa was proposed by German botanist Carl Ludwig Willdenow in 1807 and applied by him to two species, O. acuminata (now known as Prestoea acuminata) and O. praemorsa (now Wettinia praemorsa). Although these species were transferred to other genera, the genus Oreodoxa continued to be applied to a variety of superficially similar species which were not, in fact, closely related. To address this problem, American botanist Orator F. Cook created the genus Roystonea, which he named in honour of American general Roy Stone, and renamed Kunth's species Roystonea regia.
Cook considered Floridian populations to be distinct from both the Cuba R. regia and the Puerto Rican R. borinquena, and he placed them in a new species, R. floridana, which is now considered a synonym of R. regia. In 1906 Charles Henry Wright described two new species based on collections from Georgetown, British Guiana (now Guyana) which he placed in the genus Euterpe — E. jenmanii and E. ventricosa. Both species are now considered synonyms of R. regia. The name R. regia var. hondurensis was applied by Paul H. Allen to Central American populations of the species. However, Scott Zona determined that they did not differ enough from Cuban populations to be considered a separate variety.
Based on the rules of botanical nomenclature, the oldest properly published name for a species has priority over newer names. Bartram applied the Linnaean binomial Palma elata to a "large, solitary palm with an ashen white trunk topped by a green leaf sheath [the crownshaft] and pinnate leaves" growing in central Florida. While no type collection is known, there are no other native palms that would fit Bartram's description. In 1946 Francis Harper pointed out that Bartram's name was valid and proposed a new combination, Roystonea elata. Liberty Hyde Bailey's use of the name in his 1949 revision of the genus, established its usage.
Harper's new combination immediately supplanted Cook's R. floridana, but there was disagreement as to whether Cuban and Floridian populations represented a single species or two species. Zona's revision of the genus established that they both belonged to the same species. According to the rules of botanical nomenclature, the correct name of the species should have been Roystonea elata. Zona pointed out, however, that the name R. regia (or Oreodoxa regia) has a history of use in horticulture that dated from at least 1838, and that the species had been propagated around the world under that name. Roystonea elata, on the other hand, had only been used since 1949, and was used much less widely. As a result, Zona proposed that the name Roystonea regia should be conserved.
Roystonea regia is found in southern Florida, north-central and south-east Mexico, Belize, Honduras, Cuba, the Cayman Islands and The Bahamas. It has been planted throughout the tropics and subtropics as an ornamental tree.
William Bartram described the species from Lake Dexter, along the St. Johns River in the area of modern Lake and Volusia Counties in central Florida, an area well north of its modern range. The reason for its contraction in range is uncertain—it has been suggested that a severe freeze in 1835 and 1894–95 eliminated northern populations, or that land clearing by settlers eliminated most populations of the tree.
Roystonea regia leaves are used as roosting sites by Eumops floridanus, the Florida bonneted bat. It serves as a larval host plant for the butterflies Pyrrhocalles antiqua orientis and Asbolis capucinus in Cuba. In Panama (where it is a non-native species), R. regia trunks are used used by Yellow-crowned parrots Amazona ochrocephala panamensis as nesting sites. Its flowers are visited by pollen-collecting bees and it is considered a good source of nectar. Its pollen was also found in the stomachs of Phyllonycteris poeyi, the Cuban Flower Bat (a pollen-feeder) and Monophyllus redmani, Leach's Single Leaf Bat (a nectar-feeder). Artibeus jamaicensis, the Jamaican fruit bat, and Myiozetetes similis, the Social Flycatcher, feed on the fruit.
Roystonea regia is considered an invasive species in secondary forest in Panama.
Roystonea regia has been planted throughout the tropics and subtropics as an ornamental. The seed is used as a source of oil and for livestock feed. Leaves are used for thatching and the wood for construction. The roots are used as a diueretic and as a treatment for diabetes.
Roystonea regia plays an important role in popular religion in Cuba. In Santería it is associated primarily with Shango or with his father Aggayú. It also has symbolic importance in the Palo faiths and the Abakuá fraternity. In Roman Catholicism, R. regia plays an important role in Palm Sunday observances.1
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