The Arecaceae are a botanical family of perennial plants. Their growth form can be climbers, shrubs, trees and stemless plants, all commonly known as palms. Those having a tree form are colloquially called palm trees. They are flowering plants, a family in the monocot order Arecales. Currently 181 genera with around 2600 species are known, most of them restricted to tropical and subtropical climates. Most palms are distinguished by their large, compound, evergreen leaves, known as fronds, arranged at the top of an unbranched stem. However, palms exhibit an enormous diversity in physical characteristics and 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. In contemporary times, palms are also widely used in landscaping, making them one of the most economically important plants. In many historical cultures, because of their importance as food, palms were symbols for such ideas as victory, peace, and fertility. For inhabitants of cooler climates today, palms symbolize the tropics and vacations.
|Coconut palm tree Cocos nucifera in Martinique.|
Bercht. & J.Presl, nom. cons.
|Well over 2600 species in some 202 genera|
Whether as shrubs, trees, or vines, palms have two methods of growth: solitary or clustered. The common representation is that of a solitary shoot ending in a crown of leaves. This monopodial character 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 though dense clusters. The trunk develops 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 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 spadix 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 bisexual. 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 (sometimes berry-like) but some genera (e.g., Salacca) may contain two or more seeds in each fruit.
Like all monocots, palms do not have the ability to increase the width of a stem (secondary growth) via the same kind of vascular cambium found in non-monocot woody plants. This explains the cylindrical shape of the trunk (almost constant diameter) that is often seen in palms, unlike in ring-forming trees. However, many palms, like some other monocots, do have secondary growth, although because it does not arise from a single vascular cambium producing xylem inwards and phloem outwards, it is often called "anomalous secondary growth".
The 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 up to 60 m tall. The coco de mer (Lodoicea maldivica) has the largest seeds of any plant, 40–50 cm in diameter and weighing 15–30 kg each. Raffia palms (Raphia spp.) have the largest leaves of any plant, up to 25 m long and 3 m wide. The Corypha species have the largest inflorescence of any plant, up to 7.5 m tall and containing millions of small flowers. Calamus stems can reach 200 m in length.
Most palms are native to tropical and subtropical climates. Palms thrive in moist and hot climates but can be found in a variety of different habitats. Their diversity is highest in wet, lowland forests. South America, the Caribbean, and areas of the south Pacific and southern Asia are regions of concentration. Colombia may have the highest number of palm species in one country. There are some palms that are also native to desert areas such as the Arabian peninsula and parts of northwestern Mexico. Only about 130 palm species naturally grow entirely beyond the tropics, mostly in humid lowland subtropical climates, in highlands in southern Asia, and along the rim lands of the Mediterranean Sea. The northernmost native palm is Chamaerops humilis, which reaches 44°N latitude along the coast of southern France. In the southern hemisphere, the southernmost palm is the Rhopalostylis sapida, which reaches 44°S on the Chatham Islands where an oceanic climate prevails. Cultivation of palms is possible north of subtropical climates, and some higher latitude locals such as Ireland, Scotland, England, and the Pacific Northwest feature a few palms in protected locations.
Palms inhabit a variety of ecosystems. More than two-thirds of palm species live in humid moist forests, where some species grow tall enough to form part of the canopy and shorter ones form part of the understory. Some species form pure stands in areas with poor drainage or regular flooding, including Raphia hookeri which is common in coastal freshwater swamps in West Africa. Other palms live in tropical mountain habitats above 1000 m, such as those in the genus Ceroxylon native to the Andes. Palms may also live in grasslands and scrublands, usually associated with a water source, and in desert oases such as the date palm. A few palms are adapted to extremely basic lime soils, while others are similarly adapted to extreme potassium deficiency and toxicity of heavy metals in serpentine soils.
Palms are a monophyletic group of plants, meaning the group consists of a common ancestor and all its descendants. Extensive taxonomic research on palms began with botanist H.E. Moore, who organized palms into 15 major groups based mostly on general morphological characteristics. The following classification, proposed by N.W. Uhl and J. Dransfield in 1987, is a revision of Moore's classification that organizes palms into six subfamilies.
A few general traits of each subfamily are listed below.
The Coryphoideae are the most diverse subfamily, and are a paraphyletic group, meaning 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, or 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 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, spirally arranged, with a gynoecium of three joined carpels.
The Arecoideae are the largest subfamily, with six diverse tribes (Areceae, Caryoteae, Cocoseae, Geonomeae, Iriarteeae, and Podococceae) 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.
The Phytelephantoideae are a monoecious subfamily. Members of this group have distinct monopodial flower clusters. Other distinct features include a gynoecium with five to 10 joined carpels, and flowers with more than three parts per whorl. Fruits are multiple-seeded and have multiple parts.
Currently, few extensive phylogenetic studies of the Arecaceae exist. In 1997, Baker et al. explored subfamily and tribe relationships using chloroplast DNA from 60 genera from all subfamilies and tribes. The results strongly showed the Calamoideae are monophyletic, and Ceroxyloideae and Coryphoideae are paraphyletic. The relationships of Arecoideae are uncertain, but they are possibly related to the Ceroxyloideae and Phytelephantoideae. Studies have suggested the lack of a fully resolved hypothesis for the relationships within the family is due to a variety of factors, including difficulties in selecting appropriate outgroups, homoplasy in morphological character states, slow rates of molecular evolution important for the use of standard DNA markers, and character polarization. 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.
The Arecaceae are the first modern family of monocots appearing in the fossil record around 80 million years ago (Mya), during the late Cretaceous period. The first modern species, such as Nypa fruticans and Acrocomia aculeata, appeared 94 Mya, confirmed by fossil Nypa pollen dated to 94 Mya. Palms appear to have undergone an early period of adaptive radiation. By 60 Mya, 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.
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.
Along with dates mentioned above, members of the palm family with human uses are numerous.
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 those with small habitat ranges 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 (except in domesticated varieties, e.g. of peach palm). 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.
However, several factors make palm conservation more difficult. Palms live in almost every type of warm habitat and have tremendous morphological diversity. Most palm seeds lose viability quickly, and they cannot be preserved in low temperatures because the cold kills the embryo. Using botanical gardens for conservation also presents problems, since they can rarely house more than a few plants of any species or truly imitate the natural setting. Also, the risk of cross-pollination can lead to hybrid species.
The Palm Specialist Group of the World Conservation Union (IUCN) began in 1984, and has performed a series of three studies to find basic information on the status of palms in the wild, use of wild palms, and palms under cultivation. Two projects on palm conservation and use supported by the World Wildlife Fund took place from 1985 to 1990 and 1986–1991, in the American tropics and southeast Asia, respectively. Both studies produced copious new data and publications on palms. Preparation of a global action plan for palm conservation began in 1991, supported by the IUCN, and was published in 1996.
Pests that attack a variety of species of palm trees include:
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.
Panaiveriyamman was an ancient Tamil tree deity related to fertility. Named after panai, the Tamil name for the Palmyra palm, she was also known as Taalavaasini, a name that further related her to all types of palms.
Today, the palm, especially the coconut palm, remains a symbol of the 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.
Some species commonly called palms, though they are not true palms, include:
Areca is a genus of about 50 species of palms in the family Arecaceae, found in humid tropical forests from China and India, across Southeast Asia to Melanesia. The generic name Areca is derived from a name used locally on the Malabar Coast of India.Arecales
Arecales is an order of flowering plants. The order has been widely recognised only for the past few decades; until then, the accepted name for the order including these plants was Principes.Borassus
Borassus (Palmyra palm) is a genus of five species of fan palms, native to tropical regions of Africa, Asia and New Guinea.Calamus (palm)
Calamus is a genus of the palm family Arecaceae. These are among several genera known as rattan palms. There are an estimated 400 species in this genus, all native to tropical and subtropical Asia, Africa, and Australia. They are mostly leaf-climbing lianas with slender, reedy stems. To aid scrambling some species have evolved hooks on the underside of the midrib, or more commonly by modified "pinnae" or tendrils in the form of stout, backward-pointing spines. These stems may grow to lengths of 200 metres.Coccothrinax
Coccothrinax is a genus of palms in the Arecaceae family. There are more than 50 species described in the genus, plus many synonyms and sub-species. A new species (Coccothrinax torrida) was described as recently as 2006. Many Coccothrinax produce thatch. In Spanish-speaking countries, guano is a common name applied to Coccothrinax palms. The species are native throughout the Caribbean, the Bahamas, extreme southern Florida and southeastern Mexico, but most of the species are known only from Cuba.Coryphoideae
The Coryphoideae is one of five subfamilies in the palm family, Arecaceae. It contains all of the genera with palmate leaves, excepting Mauritia, Mauritiella and Lepidocaryum, all of subfamily Calamoideae, tribe Lepidocaryeae, subtribe Mauritiinae. However, all Coryphoid palm leaves have induplicate (V-shaped) leaf folds (excepting Guihaia), while Calamoid palms have reduplicate (inverted V-shaped) leaf folds. Pinnate leaves do occur in Coryphoideae, in Phoenix, Arenga, Wallichia and bipinnate in Caryota.Elaeis
Elaeis (from Greek, meaning 'oil') is a genus of palms containing two species, called oil palms. They are used in commercial agriculture in the production of palm oil. The African oil palm Elaeis guineensis (the species name guineensis referring to its country of origin) is the principal source of palm oil. It is native to west and southwest Africa, occurring between Angola and Gambia. The American oil palm Elaeis oleifera (from Latin oleifer, meaning 'oil-producing') is native to tropical Central and South America, and is used locally for oil production.Eugeissona
Eugeissona is a clustering genus of flowering plant in the palm family native to Borneo, Thailand and Malaysia. The six monoecious species provide a wide range of local uses and are commonly called bertam or wild Bornean sago. The genus is the sole representative of the Eugeissoninae having very few obvious relatives; the hermaphrodite and staminate flowers are also found in Metroxylon, however the other specialized characteristics are unique suggesting an early split and differentiation from other members of the Calameae. Fossilized pollen belonging to these plants has been recovered in the lower and middle Miocene deposits in Sarawak. The name is from two Greek words meaning "good" and "roof", due to their common use in roof thatching.Fan palm
Fan palm as a descriptive term can refer to any of several different kinds of palms (Arecaceae) in various genera with leaves that are palmately lobed (rather than pinnately compound). Most are members of the subfamily Coryphoideae, though a few genera in subfamily Calamoideae (Mauritia, Mauritiella and Lepidocaryum) also have palmate leaves. Fan palm genera include:
TrithrinaxFan palm can also be used as part of the common name of particular genera or species. Among the palms commonly known as fan palms are:
Chamaerops humilis (European fan palm)
Hyphaene petersiana (Real fan palm)
Livistona (Chinese fan palm and others)
Washingtonia (California fan palm, Mexican fan palm)
Latania (Indian Ocean fan palms)The Travellers palm (Ravenala madagascariensis), Phenakospermum (Phenakospermum guyannense), White Bird Of Paradise (Strelitzia nicolai), and New Guinea Fan Palm (Cordyline fruticosa) are sometimes called fan palms, because of their leaves' distinctive shape; however none are members of the palm family (Arecaceae).Jubaea
Jubaea is a genus of palms with one species, Jubaea chilensis or Jubaea spectabilis, commonly known as the "Chilean wine palm" or "Chile cocopalm". It is native to southwestern South America and is endemic to a small area of central Chile between 32°S and 35°S in southern Coquimbo, Valparaíso, Santiago, O'Higgins, and northern Maule regions.
It has long been assumed that the extinct palm tree of Easter Island belonged to this genus as well; however, in 2008, John Dransfield controversially placed it in its own genus, Paschalococos.List of Arecaceae genera
This is a list of all the genera in the botanical family Arecaceae, the palm tree family, arranged by tribes within the family.Livistona
Livistona is a genus of palms (family Arecaceae), native to southern, southeastern and eastern Asia, Australasia, and the Horn of Africa. They are fan palms, the leaves with an armed petiole terminating in a rounded, costapalmate fan of numerous leaflets.Livistona is closely related to the genus Saribus, and for a time Saribus was included in Livistona. Recent studies, however, have advocated separating the two groups.Livistona species are used as food plants by the larvae of some Lepidoptera species including Batrachedra arenosella (recorded on L. subglobosa) and Paysandisia archon.
Kho (L. speciosa) is the tree of Khao Kho District in Thailand.Mauritia
Mauritia is a genus of fan palms which is native to northern South America and to the Island of Trinidad in the Caribbean. Only two species are currently accepted. Mauritia flexuosa is widely distributed across northern South America as far south as Bolivia, extending north to Trinidad, while M. carana is restricted to the Amazon regions of Brazil, Venezuela, Peru, and Colombia.Pantropical
A pantropical ("all tropics") distribution is one which covers tropical regions of both hemispheres. Examples include the plant genera Acacia and Bacopa.Neotropical is a zoogeographic term that covers a large part of the Americas, roughly from Mexico and the Caribbean southwards (including cold regions in southernmost South America).
Palaeotropical refers to geographical occurrence. For a distribution to be palaeotropical a taxon must occur in tropical regions in the Old World.
According to Takhtajan (1978), the following families have a pantropical distribution:
Annonaceae, Hernandiaceae, Lauraceae, Piperaceae, Urticaceae, Dilleniaceae, Tetrameristaceae, Passifloraceae, Bombacaceae, Euphorbiaceae, Rhizophoraceae, Myrtaceae, Anacardiaceae, Sapindaceae, Malpighiaceae, Proteaceae, Bignoniaceae, Orchidaceae and Arecaceae.Pritchardia
The genus Pritchardia (Family Arecaceae) consists of between 24-40 species of fan palms (subfamily Coryphoideae) found on tropical Pacific Ocean islands in Fiji, Samoa, Tonga, Tuamotus, and most diversely in Hawaii. The generic name honors William Thomas Pritchard (1829-1907), a British consul at Fiji.Sabal
Sabal is a genus of New World palms, commonly known as palmettos. They are fan palms (subfamily Coryphoideae, tribe Sabaleae); the leaves have a bare petiole terminating in a rounded fan of numerous leaflets; in some of the species, the leaflets are joined for up to half of their length. A variable portion of the leaf petiole may remain persistent on the trunk for many years after leaf fall leaving the trunk rough and spiky, but in some, the lower trunk loses these leaf bases and becomes smooth. The fruit is a drupe.Sabal species are used as food plants by the larvae of some Lepidoptera species including Paysandisia archon.
The species are native to the subtropical and tropical regions of the Americas, from the Gulf Coast/South Atlantic states in the Southeastern United States, south through the Caribbean, Mexico, and Central America to Colombia and Venezuela.Serenoa
Serenoa repens, commonly known as saw palmetto, is the sole species currently classified in the genus Serenoa. It is a small palm, growing to a maximum height around 7–10 ft (2.1–3.0 m). It is endemic to the subtropical Southeastern United States, most commonly along the south Atlantic and Gulf Coastal plains and sand hills. It grows in clumps or dense thickets in sandy coastal areas, and as undergrowth in pine woods or hardwood hammocks.