Royal palm

Appearance

''Roystonea regia'' is a large palm which reaches a height of 20–30 metres tall, reported) and a stem diameter of about 47 centimetres . .) The trunk is stout, very smooth and grey-white in colour with a characteristic bulge below a distinctive green crownshaft. Trees have about 15 leaves which can be up to 4 m long. The flowers are white with pinkish anthers. The fruit are spheroid to ellipsoid in shape, 8.9–15 millimetres long and 7–10.9 mm 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 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 indole acetic acid, an important plant hormone....hieroglyph snipped...

Naming

In cultivation, ''Roystonea regia'' is called the Cuban royal palm or simply the royal palm. In Cuba, the tree is called the ''palma real'' or ''palma criolla''. In India, where it is widely cultivated, it is called ''vakka''. In Cambodia, where it is planted as decorative along avenues and in public parks, it is known as ''sla barang .

Distribution

''Roystonea regia'' is found in Central America, Cuba, the Cayman Islands, Hispaniola , the Lesser Antilles, The Bahamas, southern Florida, and Mexico . 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 north of its modern range, suggesting a wider distribution in the past.

''Roystonea regia'' is most abundant in Cuba, where is occurs on hillsides and valleys. In southern Florida, ''Roystonea regia'' occurs in strand swamps and hardwood hammocks. Royal Palm State Park in the Everglades was established due to the high concentration of the species.

''Roystonea'' is cultivated in tropical and subtropical climates in the United States, Australia, Brazil, and parts of southern Asia as a landscape palm. It appears to naturalise with ease, and extensive naturalised populations are present in Panama, Costa Rica, and Guyana. In the United States it grows mostly in central and southern Florida, Hawaii, Puerto Rico, and in South Texas in the Rio Grande Valley and southern California.

Habitat

''Roystonea regia'' is found in Central America, Cuba, the Cayman Islands, Hispaniola , the Lesser Antilles, The Bahamas, southern Florida, and Mexico . 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 north of its modern range, suggesting a wider distribution in the past.

''Roystonea regia'' is most abundant in Cuba, where is occurs on hillsides and valleys. In southern Florida, ''Roystonea regia'' occurs in strand swamps and hardwood hammocks. Royal Palm State Park in the Everglades was established due to the high concentration of the species.

''Roystonea'' is cultivated in tropical and subtropical climates in the United States, Australia, Brazil, and parts of southern Asia as a landscape palm. It appears to naturalise with ease, and extensive naturalised populations are present in Panama, Costa Rica, and Guyana. In the United States it grows mostly in central and southern Florida, Hawaii, Puerto Rico, and in South Texas in the Rio Grande Valley and southern California.The leaves of ''Roystonea regia'' are used as roosting sites by ''Eumops floridanus'', the Florida bonneted bat, and is used as a retreat for Cuban tree frogs , a non-native species in Florida. In Panama , its trunks are used as nesting sites by yellow-crowned parrots . The flowers of ''R. regia'' are visited by pollen-collecting bees and are considered a good source of nectar. Its pollen was also found in the stomachs of ''Phyllonycteris poeyi'', the Cuban flower bat and ''Monophyllus redmani'', Leach's single leaf bat . ''Artibeus jamaicensis'', the Jamaican fruit bat, and ''Myiozetetes similis'', the social flycatcher, feed on the fruit.

''Roystonea regia'' is the host plant for the royal palm bug, ''Xylastodoris luteolus'', in Florida. It also serves as a larval host plant for the butterflies ''Pyrrhocalles antiqua orientis'' and ''Asbolis capucinus'' in Cuba, and ''Brassolis astyra'' and ''B. sophorae'' in Brazil. It is susceptible to bud rot caused by the oomycete ''Phytophthora palmivora'' and by the fungus ''Thielaviopsis paradoxa''.

The species is considered an invasive species in secondary forest in Panama.

Reproduction

''Roystonea regia'' produces
unisexual flowers that are pollinated by animals. European honey bees and bats are reported pollinators. Seeds are dispersed by birds and bats that feed upon the fruit.

Seed germination is adjacent ligular—during germination, as the cotyledon expands it only pushes a portion of the embryo out of the seed. As a result, the seedling develops adjacent to the seed. The embryo forms a ligule, and the plumule protrudes from this. Seedlings in cultivation are reported to begin producing a stem two years after germination, at the point where they produce their thirteenth leaf. Growth rates of seedlings averaged 4.2 cm per year in Florida.

Uses

''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 diuretic, and for that reason they are added to ''tifey'', a Haitian drink, by Cubans of Haitian origin. They are also used as a treatment for diabetes.

Fibres extracted from the leaf sheath of ''R. regia'' have been found to be comparable with sisal and banana fibres, but lower in density, making it a potentially useful source for the use in lightweight composite materials. An extract from ''R. regia'' fruit known as D-004 reduces benign prostate hyperplasia in rodents. D-004, is a mixture of fatty acids, is being studied as a potential alternative to finasteride for the treatment of BPH.