- Persea
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Persea 
Persea borbonia foliage and fruit Scientific classification Kingdom: Plantae (unranked): Angiosperms (unranked): Magnoliids Order: Laurales Family: Lauraceae Genus: Persea
Mill.[1]Species See text.
Synonyms Persea is a genus of about 150 species of evergreen trees belonging to the laurel family, Lauraceae.[2] The best-known member of the genus is the avocado, P. americana, widely cultivated in subtropical regions for its large, edible fruit.
Contents
Overview
They are medium-size trees, 15-30 m tall at maturity. The leaves are simple, lanceolate to broad lanceolate, varying with species from 5-30 cm long and 2-12 cm broad, and arranged spirally or alternately on the stems. The flowers are in short panicles, with six small greenish-yellow perianth segments 3-6 mm long, nine stamens and an ovary with a single embryo. The fruit is an oval or pear-shaped drupe, with a fleshy outer covering surrounding the single seed; size is very variable between the species, from 1-1.5 cm in e.g. P. borbonia and P. indica, up to 10-20 cm in P. americana.
Distribution and ecology
The species of Persea have a disjunct distribution, with about 70 Neotropic species, ranging from Brazil and Chile in South America to Central America and Mexico, the Caribbean, and the southeastern United States; a single species, P. indica, endemic to the Macaronesian islands, including Madeira and the Canary Islands; and 80 species inhabiting east and southeast Asia. None of the species is very tolerant of severe winter cold, with the hardiest, P. borbonia, P. ichangensis and P. lingue, surviving temperatures down to about -12°C; they also require continuously moist soil, and do not tolerate drought. A number of these species are found in forests that face threats of destruction or deforestation; for example, P. meyeniana occurs in Central Chile, where historic and ongoing deforestation has reduced the habitat of the endangered Chilean Wine Palm[3] and forest system as a whole.
The Family Lauraceae was part of Gondwanaland flora and many genera also, migrated to South America via Antarctica in ocean landbridges by Paleocene time. There they spread over most of the continent. When the north American and south American tectonic plates joined in late Neogene, volcanic mountain building created island chains which later formed the meso-American landbridge. Pliocene elevation created new habitats for speciation. While some genera died out in increasingly xerophytic Africa, starting with the freezing of Antarctica about 20 million years ago and the formation of the Benguela current, others, like Beilschmiedia, and Nectandra, which also reached south and meso-America, are still surviving today in Africa in a number of species. The genus Persea, however, died out in Africa, except for Persea indica, surviving in the fog shrouded mountains of the Canary Islands, which with Madagascar constitutes Africa's Laurel forest plant refugia.
Fossil evidence indicates that the genus originated in West Africa during the Paleocene, and spread to Asia, to South America, and to Europe and thence to North America. It is thought that the gradual drying of Africa, west Asia, and the Mediterranean from the Oligocene to the Pleistocene, and the glaciation of Europe during the Pleistocene, caused the extinction of the genus across these regions, resulting in the present distribution.
Since this habitat is constantly threatened by encroching agriculture, the laurel forest animal or vegetal species had already become rare in many of its former habitats and are threatened by habitat loss.
The fruit in species of persea genus is a berry. This berries varied in shape and size, they are an important food source for birds, usually this birds are from specialized genus: Cotingidae, Columbidae, Rhamphastidae, Trogonidae, Turdidae, etc. Birds eat the whole fruit and regurgitate seeds intact, expanding the seeds in the best conditions for germination (ornitochory). In some species the seed dispersal is carried out by monkeys, chipmunks, porcupines, Opossums or fishes.
In meso-America, the genus Persea proliferated into many new species and the berries of some of them constitute a valuable food supply for the quetzal, that lives in the montane rainforests of meso-America.
The quetzal favorite fruits are berries of relatives of the avocado family. Their differing maturing times in the cloudforest determine the migratory movements of the quetzals to differing elevation levels in the forests. With a gape width of 21 mm, the quetzal swallows the small berry (aquacatillo) whole, which he catches while flying through the lower canopy of the tree, and then regurgitates the seed within 100 meters from the tree. Wheelright in 1983 observed that parent quetzals take far less time intervals to deliver fruits to the young brood than insects or lizards, reflecting the ease of procuring fruits, as opposed to capturing animal prey. Since the young are fed exclusively berries in the first 2 weeks after hatching, these berries must be of high nutritional value. Usually only the total percentage of water, sugar, nitrogen, crude fats and carbohydrates are reported by ornithologists[4] Persea species are used as food plants by the larvae of some Lepidoptera species including Giant Leopard Moth, Coleophora octagonella (feeds exclusively on P. carolinensis) and Hypercompe indecisa.
Classification
The avocado fruit, Persea americana
The genus Persea is treated in three subgenera. The Asian subgenus Machilus is treated in a separate genus Machilus by many authors, including in the Flora of China, while graft-incompatibility between subgenus Persea and subgenus Eriodaphne suggests that these too may be better treated as distinct genera, in fact Kostermans (1993) founded the genus Mutisiopersea for these. Another closely related genus, Beilschmiedia, is also sometimes included in Persea.
- Subgenus Persea - Central America. Two species.
- Persea americana Mill. – Avocado
- Persea americana var. drymifolia (Schltdl. & Cham.) S.F.Blake
- Persea americana var. floccosa (Mez) Scora
- Persea americana var. guatemalensis (L.O.Williams) Scora
- Persea americana var. nubigena (L.O.Williams) L.E.Kopp
- Persea americana var. steyermarkii (C.K.Allen) Scora
- Persea schiedeana Nees – Coyo
- Subgenus Eriodaphne (Mutisiopersea) - The Americas, Macaronesia. About 70 species, including
- Persea alpigena
- Persea borbonia (L.) Spreng. – Redbay
- Persea caerulea (Ruiz & Pav.) Mez
- Persea cinerascens
- Persea donnell-smithii Mez
- Persea indica (L.) Spreng. – Viñátigo (possibly better treated in a fourth subgenus of its own)
- Persea lingue (Ruiz & Pav.) Nees – Lingue
- Persea longipes (Schltdl.) Meisn.
- Persea meyeniana Nees
- Persea palustris (Raf.) Sarg. – Swampbay
- Persea skutchii
- Subgenus Machilus - Asia. About 80 species, including
- Persea edulis
- Persea ichangensis
- Persea japonica (Siebold & Zucc.) Kosterm.
- Persea kobu
- Persea macrantha
- Persea nanmu Oliv.
- Persea thunbergii (Siebold & Zucc.) Kosterm.
- Persea yunnanensis[5]
Formerly placed here
- Cinnamodendron cinnamomifolium (Kunth) Kosterm. (as P. cinnamomifolia Kunth or P. mexicana (Meisn.) Hemsl.)
- Laurus azorica (Seub.) Franco (as P. azorica Seub.)[5]
Etymology
Philip Miller derived Persea from the Greek name Περσεα. It was applied by Theophrastus and Hippocrates to an uncertain Egyptian tree, possibly Cordia myxa or a Mimusops species.[6]
Line notes
- ^ a b "Genus: Persea Mill.". Germplasm Resources Information Network. United States Department of Agriculture. 2007-10-05. http://www.ars-grin.gov/cgi-bin/npgs/html/genus.pl?9138. Retrieved 2011-02-05.
- ^ André Joseph Guillaume Henri Kostermans. 1993
- ^ C. Michael Hogan. 2008
- ^ http://www.avocadosource.com/CAS_Yearbooks/CAS_83_1999/CAS_1999_PG_163-171.pdf
- ^ a b "GRIN Species Records of Persea". Germplasm Resources Information Network. United States Department of Agriculture. http://www.ars-grin.gov/cgi-bin/npgs/html/splist.pl?9138. Retrieved 2011-02-05.
- ^ Quattrocchi, Umberto (2000). CRC World Dictionary of Plant Names. 3 M-Q. CRC Press. p. 2015. ISBN 9780849326776. http://books.google.com/books?id=kaN-hLL-3qEC&.
References
- André Joseph Guillaume Henri Kostermans. 1993. Mutisiopersea Kostermans, a new genus in Lauraceae. Rheedea 3: 132–135.
- C. Michael Hogan. 2008. Chilean Wine Palm: Jubaea chilensis, GlobalTwitcher.com, ed. Nicklas Stromberg
- Lucille E. Kopp. 1966. "A taxonomic revision of the genus Persea in the Western Hemisphere (Persea-Lauracese)" Memoirs of the New York Botanical Garden 14(1): pp. 1-117
External links
- Avocado source Extensive information on the Avocado and the genus generally, particularly the subgenera Persea and Eriodaphne
- Flora of North America: Persea
- Flora of China: Machilus Full list of species in Machilus in China
Categories:- Persea
- Laurales genera
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