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Roystonea

Cladus: Eukaryota
Regnum: Plantae
Divisio: Magnoliophyta
Classis: Liliopsida
Subclassis: Commelinidae
Ordo: Arecales
Familia: Arecaceae
Subfamilia: Arecoideae
Tribus: Areceae
Subtribus: Roystoneinae
Genus: Roystonea
Species: R. altissima - R. borinquena - R. dunlapiana - R. lenis - R. maisiana - R. oleracea - R. princeps - R. regia - R. stellata - R. violacea

Name

Roystonea O.F.Cook

References

* Cook, O.F. Science, ser. 2, 12: 479. 1900. Type: Roystonea regia (Kunth)
* Riffle, Robert L. & Craft, Paul 2003: An Encyclopedia of Cultivated Palms. Portland: Timber Press. (Page 441) ISBN-10: 0881925586 / ISBN-13: 978-0881925586.

Roystonea is a genus of eleven species of monoecious palms, native to the Caribbean Islands, and the adjacent coasts of Florida, Central and South America. Commonly known as the royal palms, the genus was named for Roy Stone, a U.S. Army engineer. It contains some of the most recognizable and commonly cultivated palms in tropical and subtropical regions.

Description
Detail of the base of the stem of Roystonea dunlapiana showing columnar stem and leaf scars.

Roystonea is a genus of large, unarmed, single-stemmed palms with pinnate leaves. The large stature and striking appearance of a Roystonea palm makes it a notable aspect of the landscape. The stems, which were compared to stone columns by Louis and Elizabeth Agassiz in 1868, are smooth and columnar, although the trunks of R. altissima and R. maisiana are more slender than those of typical royal palms. Stems often are swollen and bulging along portions of their length, which may reflect years where growing conditions were better or worse than average. Leaf scars are often prominent along the stem, especially in young, rapidly growing individuals. Stem color ranges from gray-white to gray-brown except in R. violacea, which have violet-brown or mauve stems. The largest royal palm, R. oleracea, reaches heights of 40 metres (130 ft), but most species are in the 15 to 20 m (49 to 66 ft) range.[2]
Close up of crown of Roystonea regia showing smooth tapering leaf sheath and fresh leaf scars, Kolkata, India


Roystonea leaves consist of a sheathing leaf base, a petiole, and a rachis. The leaf base forms a distinctive green sheath around the uppermost portion of the trunk. Known as the crownshaft, this sheath extends 1.4–2 metres (4 ft 7 in–6 ft 7 in) down the trunk. The petiole connects the lead base with the rachis. Zona only reported petiole lengths for three of the 10 species, ranging from 20 to 100 centimetres (8 to 39 in). The rachis is pinnately divided and ranges from 3.2 to 5.8 m (10 to 19 ft) long. The leaf segments themselves range in length from 60 to 79 cm (24 to 31 in) in R. altissima up to as much as 132 cm (52 in) in R. lenis. They are arranged in two or three planes along the rachis. Many authors have reported that the leaves R. oleracea are arranged in a single plane, but American botanist Scott Zona reported that this is not the case.[2]

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.[3] Some species so closely resemble one another that scientific differentiation is by inflorescence detail; flower size, color, etc.

Taxonomy

Roystonea is placed in the subfamily Arecoideae and the tribe Roystoneae.[4] 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.[5] As of 2008, there appear to be no molecular phylogenetic studies of Roystonea[4] One species is known only from two fossilized flowers preserved in dominican amber which were described in 2002.[6]

Species

* Roystonea altissima (Mill.) H.E.Moore
* Roystonea borinquena O.F.Cook
* Roystonea dunlapiana P.H.Allen
* Roystonea lenis León
* Roystonea maisiana (L.H.Bailey) Zona
* Roystonea oleracea (Jacq.) O.F.Cook
* † Roystonea palaea Poinar, 2002 (Miocene, Hipaniola)
* Roystonea princeps (Becc.) Burret
* Roystonea regia (Kunth) O.F.Cook
* Roystonea stellata León
* Roystonea violacea León


Distribution

Roystonea has a circum-Caribbean distribution which ranges from southern Florida in the north, to southern Mexico, Honduras and Nicaragua in the east and Venezuela and Colombia in the south. Species are found throughout the Caribbean, although only Jamaica (with two native species) and Cuba (with five native species) have more than one native species.[2]

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

Though mainly a decorative plant, royal palms do have some minor agricultural uses. The heart of the palm is used to make salad in some parts of the Caribbean, and its seeds can be used as substitutes for coffee beans.[7]

Cultivation in the United States of America

While royal palms are considered a "tropical" palm, they do grow in favored microclimates in central Florida, e.g. some areas around Tampa Bay, Cape Canaveral, Orlando. There are even a few north of those areas that are seen to survive but grow slower such as Daytona Beach and Jacksonville. 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, and in the Rio Grande Valley of South Texas. Royals are being increasingly planted on Galveston Island where they do very well and as far north as Houston where individual Royals have grown 20-30 feet tall south of Interstate 10.

References

1. ^ O.F. Cook, Science, ser. 2, 12:479. 1900. Type:R. regia (Kunth)
2. ^ a b c Zona, Scott (December 1996). "Roystonea (Arecaceae: Arecoideae)". Flora Neotropica 71: 1–35. "no".
3. ^ Riffle, Robert L. and Craft, Paul (2003) An Encyclopedia of Cultivated Palms. Portland: Timber Press. (Page 441) ISBN 0-88192-558-6 / ISBN 978-0-88192-558-6
4. ^ a b Roncal, Julissa; Scott Zona; Carl E. Lewis (2008). "Molecular Phylogenetic Studies of Caribbean Palms (Arecaceae) and Their Relationships to Biogeography and Conservation". The Botanical Review 74 (1): 78–102. doi:10.1007/s12229-008-9005-9. "no".
5. ^ Asmussen, Conny B.; John Dransfield; Vinnie Deickmann; Anders S. Barfod; Jean-Christophe Pintaud; William J. Baker (2006). "A new subfamily classification of the palm family (Arecaceae): evidence from plastid DNA phylogeny". Botanical Journal of the Linnean Society 151 (1): 15–38. doi:10.1111/j.1095-8339.2006.00521.x. "no".
6. ^ Poinar, G. (2002). "Fossil palm flowers in Dominican and Baltic amber". Botanical Journal of the Linnean Society 139 (4): 361–367. doi:10.1046/j.1095-8339.2002.00052.x.
7. ^ Thomas, Hugh (1971). Cuba; the pursuit of freedom. New York: Harper & Row Publishers, p. 18.

* Kew Palms Checklist: Roystonea
* Flora of North America: Roystonea

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Source: Wikipedia, Wikispecies: All text is available under the terms of the GNU Free Documentation License