Arecaceae

| diversity = Well over 2000 species in some 200 genera | diversity_link = list of Arecaceae genera

| authority = Schultz Sch.}} Arecaceae or Palmae (also known by the name Palmaceae, which is considered taxonomically invalid, or by the common name palm tree), is a family of flowering plants, the only family in the monocot order Arecales. There are roughly 202 currently known genera with around 2600 species, most of which are restricted to tropical, subtropical, and warm temperate climates. Most palms are distinguished by their large, compound, evergreen leaves arranged at the top of an unbranched stem. However, many palms are exceptions to this statement, and palms in fact exhibit an enormous diversity in physical characteristics. As well as being morphologically diverse, palms also inhabit nearly every type of habitat within their range, from rainforests to deserts.

Palms are among the best known and most extensively cultivated plant families. They have been important to humans throughout much of history. Many common products and foods are derived from palms, and palms are also widely used in landscaping for their exotic appearance, making them one of the most economically important plants. In many historical cultures, palms were symbols for such ideas as victory, peace, and fertility. Today, palms remain a popular symbol for the tropics and vacations.

Morphology

in Palm Canyon, California is growing alongside a stream running through the desert.]] Whether as shrubs, trees, or vines, palms have two methods of growth: solitary or clusters. The common representation is that of a solitary shoot ending in a crown of leaves. This monopodial behavior may be exhibited by prostrate, trunkless, and trunk-forming members. Some common palms restricted to solitary growth include Washingtonia and Roystonea. Palms may instead grow in sparse to dense clusters. The trunk will develop an axillary bud at a leaf node, usually near the base, from which a new shoot emerges. The new shoot, in turn, produces an axillary bud and a clustering habit results. Exclusively sympodial genera include many of the rattans, Guihaia, and Rhapis. Several palm genera have both solitary and clustering members. Palms which are usually solitary may grow in clusters, and vice versa. These aberrations suggest that the habit operates on a single gene.

Palms have large evergreen leaves that are either palmately ('fan-leaved') or pinnately ('feather-leaved') compound and spirally arranged at the top of the stem. The leaves have a tubular sheath at the base that usually splits open on one side at maturity. The inflorescence is a panicle or spike surrounded by one or more bracts or spathes that become woody at maturity. The flowers are generally small and white, radially symmetric, and can be either uni- or bi-sexual. The sepals and petals usually number three each, and may be distinct or joined at the base. The stamens generally number six, with filaments that may be separate, attached to each other, or attached to the pistil at the base. The fruit is usually a single-seeded drupe, but some genera (e.g. Salacca) may contain two or more seeds in each fruit. , India]]

Arecaceae are notable among monocots for their height and for the size of their seeds, leaves, and inflorescences. Ceroxylon quindiuense, Colombia's national tree, is the tallest monocot in the world, reaching heights of 60 meters. The Coco de mer (Lodoicea maldivica) has the largest seeds of any plant, 40-50 cm in diameter and weighing 15–30 kilograms each. Raffia palms (Raphia spp.) have the largest leaves of any plant, up to 25 meters long and 3 meters wide. The Corypha species have the largest inflorescence of any plant, up to 7.5 meters tall and containing millions of small flowers.

Range and habitat

, India]] Most palms grow in the tropics. They are abundant throughout the tropics, and thrive in almost every habitat therein. Their diversity is highest in wet, lowland tropical forests, especially in ecological "hotspots" such as Madagascar, which has more endemic palms than all of Africa. Colombia may have the highest number of palm species in one country.

It is estimated that only 130 palm species grow naturally beyond the tropics, mostly in the subtropics. The northernmost native palm is Chamaerops humilis, which reaches 44°N latitude in southern France. The southernmost palm is the Rhopalostylis sapida, which reaches 44°S on the Chatham Islands where an oceanic climate prevails. A few general traits of each subfamily are listed.

Coryphoideae is the most diverse subfamily and is a paraphyletic group, meaning that all members of the group share a common ancestor but the group does not include all the ancestor's descendants. Most palms in this subfamily have palmately lobed leaves and solitary flowers with three, sometimes four carpels. The fruit normally develops from only one carpel. Subfamily Calamoideae includes the climbing palms such as rattans. The leaves are usually pinnate; derived characters (synapomorphies) include spines on various organs, organs specialized for climbing, an extension of the main stem of the leaf bearing reflexed spines, and overlapping scales covering the fruit and ovary. Subfamily Nypoideae contains only one genus and one species, Nypa fruticans, which has large pinnate leaves. The fruit is unusual in that it floats, and the stem is dichotomously branched, also unusual in palms. Subfamily Ceroxyloideae has small to medium-sized flowers that spirally arranged, with a gynoecium of three joined carpels. Arecoideae is the largest subfamily with six diverse tribes containing over 100 genera. All tribes have pinnate or bipinnate leaves and flowers arranged in groups of three, with a central pistillate and two staminate flowers. Phytelephantoideae is a monoecious subfamily. Members of this group have distinct monopodial flower clusters. Other distinct features include a gynoecium with five to ten joined carpels, and flowers with more than three parts per whorl. Fruits are multiseeded and have multiple parts. However, hybridization has been observed among Orbignya and Phoenix'' species, and using chloroplast DNA in cladistic studies may produce inaccurate results due to maternal inheritance of the chloroplast DNA. Chemical and molecular data from non-organelle DNA, for example, could be more effective for studying palm phylogeny.

Selected genera

, Pakistan]]

Archontophoenix—Bangalow palm

Areca—Betel palm

Bactris—Pupunha

Beccariophoenix—Beccariophoenix alfredii

Bismarckia—Bismark palm

Borassus—Palmyra palm, Sugar palm, Toddy palm

Calamus—Rattan palm

Cocos—Coconut

Copernicia—Carnauba wax palm

Corypha—Gebang palm, Buri palm or Talipot palm

Elaeis—Oil palm

Euterpe—Cabbage Heart palm, Açaí Palm

Hyphaene—Doum Palm

Jubaea—Chilean Wine Palm, Coquito palm

Latania—Latan palm

Livistona—Cabbage Palm

Mauritia—Moriche Palm

Metroxylon—Sago palm

Nypa—Nipa Palm

Phoenix—Date palm

Phoenix sylvestris—Wild date palm

Raphia—Raffia palm

Roystonea—Royal palm

Sabal—Palmettos

Salacca—Salak

Syagrus—Queen palm

Trachycarpus—Windmill palm, Kumaon palm

Veitchia—Manila palm, Joannis palm

Washingtonia—Fan palm

See list of Arecaceae genera arranged by taxonomic groups or by alphabetical order for a complete listing of genera.

Evolution

Arecaceae is the first modern family of monocots that is clearly represented in the fossil record. Palms first appear in the fossil record around 80 million years ago, during the late Cretaceous Period. The first modern species, such as Nypa fruticans and Acrocomia aculeata, appeared 69-70 million years ago, confirmed by fossil Nypa pollen dated to 70 million years ago. Palms appear to have undergone an early period of adaptive radiation. By 60 million years ago, many of the modern, specialized genera of palms appeared and became widespread and common, much more widespread than their range today. Because palms separated from the monocots earlier than other families, they developed more intrafamilial specialization and diversity. By tracing back these diverse characteristics of palms to the basic structures of monocots, palms may be valuable in studying monocot evolution. Several species of palms have been identified from flowers preserved in amber including Palaeoraphe dominicana and Roystonea palaea‎.

Evidence can also be found in samples of petrified palmwood.

Uses

Human use of palms is as old or older than human civilization itself, starting with the cultivation of the date palm by Mesopotamians and other Middle Eastern peoples 5000 years or more ago. Date wood, pits for storing dates, and other remains of the date palm have been found in Mesopotamian sites. The Date Palm had a tremendous effect on the history of the Middle East. W.H. Barreveld wrote:

:"One could go as far as to say that, had the date palm not existed, the expansion of the human race into the hot and barren parts of the "old" world would have been much more restricted. The date palm not only provided a concentrated energy food, which could be easily stored and carried along on long journeys across the deserts, it also created a more amenable habitat for the people to live in by providing shade and protection from the desert winds (Fig. 1). In addition, the date palm also yielded a variety of products for use in agricultural production and for domestic utensils, and practically all parts of the palm had a useful purpose." and at least 22 times in the Quran.

Arecaceae has great economic importance including coconut products, oils, dates, palm syrup, ivory nuts, carnauba wax, rattan cane, raffia and palm wood.

Along with dates mentioned above, members of the Palm Family with human uses are numerous.

The type member of Arecaceae is the Areca palm, the fruit of which, the betel nut, is chewed with the betel leaf for intoxicating effects (Areca catechu).

Carnuba wax is harvested from the leaves of a Brazilian palm (Copernicia).

Rattans, whose stems are used extensively in furniture and baskets are in the genus Calamus.

Palm oil is an edible vegetable oil produced by the oil palms in the genus Elaeis.

Several species are harvested for heart of palm, a vegetable eaten in salads.

Sap of the nipa palm Nypa is used to make vinegar.

Palm sap is sometimes fermented to produce palm wine or toddy, an alcoholic beverage common in parts of Africa, India, and the Philippines.

Dragon's blood, a red resin used traditionally in medicine, varnish, and dyes, may be obtained from the fruit of Daemonorops species.

Coconut is the edible fruit of the coconut palm (Cocos nucifera).

Coir is a coarse water-resistant fiber extracted from the outer shell of coconuts, used in doormats, brushes, mattresses, and ropes. In India, beekeepers use coir in their bee smokers.

Some indigenous groups living in palm-rich areas use palms to make many of their necessary items and food. Sago, for example, a starch made from the pith of the trunk of the sago palm Metroxylon sagu, is a major staple food for lowland peoples of New Guinea and the Moluccas. This is not the same plant commonly used as a house plant and called "sago palm."

Panama hats are woven from the leaves of the "Panama Hat" palm.

Palm wine is made from Jubaea also called Chilean wine palm, or coquito palm

Recently the fruit of the açaí palm Euterpe has been used for its reputed healthful benefits.

Saw palmetto (Serenoa repens) is under investigation as a drug for treating enlarged prostates.

Palm leaves are also valuable to some peoples as a material for thatching, basketry, clothing, and in religious ceremonies (see "Symbolism" below). For more details, see hardy palms.

The southeastern state of South Carolina is nicknamed the Palmetto State after the Cabbage Palmetto, logs from which were used to build the fort at Fort Moultrie. During the American Revolutionary War they were invaluable to those defending the fort, because their spongy wood absorbed or deflected the British cannonballs. Some palms can be grown as far north as Maryland, southern Ohio and even up along the Pacific coast to Oregon, Washington and British Columbia, where ocean winds have a warming effect. There have even been known species of transplanted palms that have survived as far north as Devon. The Chinese Trachycarpus fortunei is being grown experimentally on the Faroe Islands at 62°N, with young plants doing well so far.

Endangered species

, a critically endangered species endemic to the Hawaiian Islands.]] Like many other plants, palms have been threatened by human intervention and exploitation. The greatest risk to palms is destruction of habitat, especially in the tropical forests, due to urbanization, wood-chipping, mining, and conversion to farmland. Palms rarely reproduce after such great changes in the habitat, and palms with a small habitat range are most vulnerable to them. The harvesting of heart of palm, a delicacy in salads, also poses a threat because it is derived from the palm's apical meristem, a vital part of the palm that cannot be regrown. The use of rattan palms in furniture has caused a major population decrease in these species that has negatively affected local and international markets as well as biodiversity in the area. The sale of seeds to nurseries and collectors is another threat, as the seeds of popular palms are sometimes harvested directly from the wild. At least 100 palm species are currently endangered, and nine species have reportedly recently become extinct.

The rarest palm known is the Hyophorbe amaricaulis. The only living individual that remains is at the Botanic Gardens of Curepipe in Mauritius.

Pest species

Pests that attack a variety of species of palm trees include:

Raoiella indica, the red palm mite

Symbolism

The palm branch was a symbol of triumph and victory in pre-Christian times. The Romans rewarded champions of the games and celebrated military successes with palm branches. Early Christians used the palm branch to symbolize the victory of the faithful over enemies of the soul, as in the Palm Sunday festival celebrating the triumphal entry of Jesus into Jerusalem. In Judaism, the palm represents peace and plenty, and is one of the Four Species of Sukkot; the palm may also symbolize the Tree of Life in Kabbalah. Today, the palm, especially the coconut palm, remains a symbol of the stereotypical tropical island paradise. Palms appear on the flags and seals of several places where they are native, including those of Haiti, Guam, Saudi Arabia, Florida and South Carolina.

See also

Travellers palm—a palm-like tree belonging to order Zingiberales

Sago palm—a palm-like cycad (a gymnosperm)

Toddy tapping—palm wine making process

Postelsia—called the "sea palm" (a brown algae)

Hardy palms—palms able to withstand colder temperatures

List of foliage plant diseases (Palmae)

References

C. H. Schultz-Schultzenstein (1832). Natürliches System des Pflanzenreichs..., 317. Berlin, Germany.

Dransfield J., Uhl N.W., Asmussen C.B., Baker W.J., Harley M.M., Lewis C.E. (2005). "A new phylogenetic classification of the palm family, Arecaceae". Kew Bulletin 60: 559–569. [latest Arecaceae or Palmae classification]

Hahn, W.J. 2002. A Molecular Phylogenetic Study of the Palmae (Arecaceae) Based on atpB, rbcL, and 18S nrDNA Sequences. Systematic Botany 51(1): 92-112.

External links

Palmpedia A wiki based site dedicated to high quality images and information on palm trees.

Guide to Palms A collection of palm images, scientific data, and horticultural information hosted by Fairchild Tropical Botanic Garden, Miami.

Kew Botanic Garden's Palm Genera list A list of the currently acknowledged genera by Kew Royal Botanic Gardens in London, England.

PACSOA Palm and Cycad Societies of Australia palm species listing with images.

Palm & Cycad Societies of Florida, Inc. (PACSOF), which includes pages on Arecaceae taxonomy and a photo index.

Scanpalm - Everything about palms in Scandinavia

Palm stability

Category:Commelinid families Category:Tropical agriculture