Palms are monocots, included in the section of Angiosperms characterized by bearing a single seed leaf. Scientifically, palms are classified as belonging to the family Palmae (the alternative name is Arecaceae), are perennial and distinguished by having woody stems.
According to Uhl and Dransfield (1987), the palm family consists of six subfamilies, each representing a major line of evolution. The Coryphoideae is the subfamily with the most unspecialized characters. It is followed by the Calamoideae, Nypoideae, Ceroxyloideae, Arecoideae and Phytelephantoideae subfamilies; the last exhibiting the greatest number of specialized characters. The foregoing names are based on the genus originally thought to be most characteristic of each subfamily, all of which have species of economic importance. These are: the talipot palm (Corypha), rattan palm (Calamus), nipa palm (Nypa), Andean wax palm (Ceroxylon), betel nut palm (Areca) and South American vegetable ivory palm (Phytelephas).
About 200 palm genera are currently recognized. The number of palm species is much less precise because of conflicting concepts by palm taxonomists as to what constitutes a distinct species, and the need to revise a number of large genera. In the literature, the number of palm species is often given as approximately 2,500, a figure that can be used to give an idea of the taxonomic complexity of the palm family.
Natural history information on the palm family can be found in Corner (1966). Palm anatomy and structural biology have been the subjects of studies by Tomlinson (1961; 1990). Illustrated books which provide general information on the more common palms of the world include McCurrach (1960), Langlois (1976), Blombery and Rodd (1982), Lötschert (1985), Del Cañizo, 1991, Stewart (1994) and Jones (1995).
The stem or trunk is a principal means of describing and identifying palms. There are five basic stem types: solitary, clustering, aerial branching, subterranean branching and climbing. The first two types are not mutually exclusive; in some instances the same species may exhibit either a solitary or clustering habit.
Solitary palms. (Fig. 1-1,C). The single-stemmed growth habit is very common and is characteristic of many of the palms cultivated for ornamental and economic purposes. Great variability exists in both the height and diameter of solitary palms. At one extreme is the ornamental potato-chip palm (Chamaedorea tuerckheimii) which has a stem no larger than the shaft of a pencil and may reach a height of only 30 cm. At the other extreme are the Chilean wine palm (Jubaea chilensis) with a stem diameter up to 2 m and the Andean wax palm (Ceroxylon alpinum) which may reach a height of 60 m. The economic disadvantage of solitary palms is that they must be propagated by seed and are vulnerable to fatal damage to the single growing tip.
Clustering palms. (Fig. 1-1,B). Multiple-stemmed palms are also quite common. From a common root system, the palm produces suckers (basal offshoots) at or below ground level; the suckers growing to maturity and replacing the oldest stems as they die. Clustering palms may be sparse or dense; in the latter they may form thickets. Numerous examples of clustering palms are found among the popular ornamental species of the genus Chamaedorea; another is the date palm (Phoenix dactylifera). However, the date palm, in formal cultivation, typically has its suckers removed giving it the appearance of a solitary palm. Many clustering palms can be propagated by separating and transplanting young suckers, making them easier to cultivate.
Aerial branching palms. (Fig. 1-1,A). Aerial branching in palms is unusual and only found naturally in species of the genera Hyphaene and Dypsis, as well as in the rattan genera Korthalsia and Laccosperma. Branching occurs by equal forking (dichotomous branching) at the growth point and, in Hyphaene compressa, may occur as many as five times. Because of sublethal damage to the growing point by insects or a physical force such as lightning, aerial branching can occur abnormally in solitary palms. Examples of this are found in the coconut (Cocos nucifera) and palmyra (Borassus flabellifer). No technique has yet been devised to induce abnormal aerial branching for economic purposes.
Subterranean branching palms. (Fig. 1-1,D). Subterranean branching occurs by at least two processes. Nipa palm (Nypa fruticans) is an example of dichotomous branching; the salak palm (Salacca zalacca) is representative of lateral branching and is similar to the type of branching which takes place in dicots with branches developing from the growth of lateral meristems. Palms producing subterranean branches by either process can be vegetatively propagated by separating and transplanting individual branches.
Climbing palms. (Fig. 1-2). About 600 species of palms in 15 genera have a climbing growth habit. Most noteworthy is the genus Calamus--the largest genus in the palm family with approximately 350 described species--source of nearly all commercial rattan. The majority of climbing palms are also clumping palms, sending out new shoots from the root system.
Initially erect, the slender stems seek out trees for support and climb up into the forest canopy by means of recurved hooks and spines growing on the stem, leaves and inflorescences. In all climbing palms the leaves are pinnate and grow along the stem instead of forming a dense crown. The stems of climbing palms, more often referred to as canes, are solid in contrast to bamboo poles which are almost always hollow.
Palm leaves are as variable as palm growth habits. In a forest setting, the leaves of palms are generally large and in many instances spectacular, making them a key aspect of identification. Palms typically bear their leaves, frequently referred to as fronds, in a crown at the top of the stem. Some exceptions to this leaf arrangement occur, such as in the ornamentally-popular lady palms (Rhapis spp.) which have leaves distributed along the upper stem. Among the acaulescent (stemless) palms, leaves may appear to be emerging from the root system but are in fact growing from the subterranean stem.
Four basic forms are characteristic of palm leaves: pinnate, palmate, bipinnate and entire
Pinnate leaves. (Fig. 1-3,D) Pinnate leaves are the most common type found in the palm family. They are divided into leaflets attached to a central leaf axis (the rachis) and often resemble a feather, hence palms bearing such foliage are often referred to as being feather-leaved or simply feather palms. Pinnate leaves exhibit an extreme size-range in the Palmae, varying from (including the petiole) well under 1 m in length in species of Chamaedorea to 25 m long in Raphia regalis. The latter is reputed to be a world record for the plant kingdom. All five major economic palms have pinnate leaves: coconut (Cocos nucifera), African oil palm (Elaeis guineensis), date (Phoenix dactylifera), betel nut palm (Areca catechu) and pejibaye (Bactris gasipaes).
Palmate leaves. (Fig. 1-3,A) These are also known as fan-leaved
or fan palms. Palmate leaves have extended leaf parts (lamina) which are
circular or semi-circular, divided into segments and radiate out from the
point where they are attached to the petiole. Laminae may be slightly divided
to being divided nearly to the leaf base. In size, leaves may be not much
larger than a human hand in the lady palms (Rhapis spp.), to a maximum
of 5 m across such as in the talipot palm (Corypha umbraculifera).
The most important economic palm with palmate leaves is the palmyra palm
Figure 1-3. Palm Leaf Types. A. A palmate leaf, as in the Mexican
fan palm (Washingtonia robusta). B. An entire leaf, as in the necklace
palm (Chamaedorea geonomiformis). C. A bipinnate leaf, as in the fishtail
palms (Caryota spp.). D. A pinnate leaf, as in the nipa palm (Nypa fruticans).
Bipinnate leaves. (Fig. 1-3,C) Bipinnate means twice-divided and gives leaflets (pinnules) a resemblance to a fishtail. This leaf type is rare in the Palmae, apparently restricted to Caryota spp., the fishtail palms. Individual fronds are as much as 4 m long and 3 m wide, depending upon the species.
Entire leaves. (Fig. 1-3,B) Entire leaves have a basic structure that is similar to pinnate leaves except that they are simple and undivided. Only about five palm genera have species with entire leaves; the largest and most beautiful is the diamond-shaped leaf of Johannesteijsmannia magnifica.
In the palm family as a whole, from as little as three years to 40 years or more are required before individual palm species reach maturity and begin to flower and produce fruit.
Examples of rapid sexual maturity are found among Chamaedorea spp., whereas the buri palm (Corypha utan) is one of the slowest to mature.
Figure 1-4 demonstrates the variability of fruits in the palm family. Illustrations A through F depict a representative fruit from each genus which gives its name to a palm subfamily. In terms of weight and size, palm seeds exhibit extreme differences. An individual seed of the popular ornamental parlor palm (Chamaedorea elegans) weighs only 0.23 g, as compared to the massive seed of the double coconut (Lodoicea maldivica) which weighs as much as 20 kg. The double coconut has the distinction of bearing the largest seed in the plant kingdom.
A cross-section of a palm fruit is provided in Figure 1-4,G. It serves
to introduce the terminology associated with the different parts of the
palm fruit to be employed in subsequent discussions.
Geographically, palms can be found in habitats ranging from southern France where the European fan palm (Chamaerops humilis) naturally occurs at 44o north latitude, to Chatham Island, New Zealand, at 44o south latitude, where the shaving brush palm (Rhopalostylis sapida) is native. However, despite this impressive spread of latitude, the overwhelming majority of palm species are native to the tropical regions of the earth. Dowe (1992) estimated that only about 130 palm species occur naturally beyond the tropical latitudes (23.5o N. & S.).
Detailed data do not yet exist on a global basis as to the precise habitat of each palm species, and therefore it is somewhat difficult to discuss palms in terms of common habitat types. Nevertheless, on the basis of what we do know, palm habitats can be generalized into five types: forest habitats; montane habitats; grassland and scrubland habitats; desert habitats; and unusual soil-type habitats.
Forest habitats. Included here are both closed forest and open forest. Palms are predominantly forest species, as evidenced by two recent studies in South America. According to a habitat characterization of native Peruvian palms, 90 percent of the species occur in forests (Kahn and Moussa, 1994); across the continent in the Brazilian state of Espírito Santo, part of the Atlantic Forest, Fernandes (1993) did a similar study and found that 27 of the 30 native palms (90 percent) also were forest species.
Within tropical forests, individual palm species may be tall enough to be emergent and to form a part of the canopy or they may be understory species of short stature adapted to shady conditions. From the standpoint of forest degradation or destruction, it is the understory species which seldom survive, whereas some emergent species may appear actually to thrive as a result of disturbance.
The tropical forest habitat is not homogenous. Apart from the lands of adequate drainage, there are some areas subject to poor drainage or periodic flooding. Such areas are characterized by distinct vegetation associations with palms often playing a principal role. In South America, for example, the moriche palm (Mauritia flexuosa) forms extensive almost pure stands where conditions are swampy. To cite an example from Africa, the wine palm of West Africa, Raphia hookeri, is abundant in coastal freshwater swamps. And in Southeast Asia, the nipa palm (Nypa fruticans) forms dense stands in estuaries of brackish water.
Well-drained coastal areas forming a part of the tropical forest habitat likewise have some distinctive palm communities. The best example of this is the coconut palm (Cocos nucifera).
Montane habitats. Tropical montane habitats are generally defined as being above 1,000 m. Any combination of lower temperatures caused by altitude, extremely wet conditions due to clouds and complex topography creates unique ecological niches to which certain palm species have become adapted. The Andean wax palms (Ceroxylon spp.), for example, are found only in montane forests. In Africa, the Senegal date palm (Phoenix reclinata) occurs both in lowland and montane forests. The montane forests in Asia do not appear to have any palm genera unique to the habitat but do have numerous species of genera common in the lowlands, such as the rattans (Calamus spp.)
Grassland and scrubland habitats. There is less palm species diversity in grasslands and scrublands, but the palms that do occur may be present in fairly large populations. Examples are the carnaúba wax palm (Copernicia prunifera) of northeastern Brazil, the vegetable ivory palm of Africa (Hyphaene petersiana) and the palmyra palm (Borassus flabellifer) of Asia. In apparently all instances, palms in these habitats are found in association with some water source, e.g. stream valleys, perched water tables or the like.
Desert habitats. These dry habitats are generally defined as areas receiving less than 254 mm of annual rainfall and represent true desert. Palms in a desert habitat are often referred to as oasis palms. The occurrence of palms in such dry habitats appears, in most cases, to represent relict distributions from previous geologic periods of more favorable rainfall conditions. Examples of oasis palms are the date palm (Phoenix dactylifera), California fan palm (Washingtonia filifera) and the Central Australian cabbage palm (Livistona mariae).
Unusual soil-type habitats. Soils derived primarily from limestone can produce extremely basic soils which support a distinctive flora. The same is true of very acidic soils rich in heavy metals (chromium, iron, copper or manganese), which are often referred to as being ultrabasic or serpentinic soils. Certain palm species tolerate such extreme soil conditions. A number of palms in the Caribbean region are adapted to limey soils, such as the thatch palms (Thrinax spp.). In the Pacific island of New Caledonia, to cite another example, ten of the native palm species are found only on serpentinic soils.
The term "palm," correctly-applied, refers to plants which are members of the Palmae, but by popular usage has also been applied to plants which resemble palms in some ways. At least seven plants have a common name which includes the word "palm," but which are not palms in the scientific sense. It is useful to clear up this confusion and dispense with the false palms as being beyond the scope of this study.
Travellerís palm. (Fig. 1-5,A) Ravenala madagascariensis, Strelitziaceae family, is a woody tree with a palm-like stem. It is native to Madagascar and widely cultivated as an ornamental throughout the tropics. Individual leaves bear greater resemblance to a banana plant (to which it is related) than a palm; they are arranged in two distinct ranks in the same plane forms a fan-shaped head. Flowers of the travellerís palm are similar to those of the bird-of-paradise plant. The vernacular name of the travellerís palm is said to derive from the fact that the cup-like leaf bases hold water which travellers could drink.
Sago palm. (Fig. 1-5,B) Major confusion is associated with this common name because it refers to the true palm Metroxylon sagu as well as to the palm-like Asian cycad Cycas revoluta, in the family Cycadaceae. Both the stem (which is sometimes branching) and the terminal crown of pinnate leaves of Cycas revoluta are similar to those of a true palm. However, Cycas revoluta leaves are stiff and borne as a rosette not singly as in palms; the male inflorescence resembles a cone, a key identifying character. Cycas revoluta is the most widely cultivated cycad. Edible starch, "sago," can be extracted from the stem of both Metroxylon sago and Cycas revoluta, which explains the shared common name.
Palm lily or ti palm. (Fig. 1-5,C) The popular ornamental plants Cordyline australis and C.terminalis of the agave family (Agavaceae) bear these common names. They are native to, respectively, New Zealand and East Asia. The branching habit gives the palm lily a resemblance to the branching palm Hyphaene, but has sword-like leaves crowded together at the end of the branches. These two species of Cordyline resemble plants in the genus Dracaena, with which they are often confused.
Screw palm. (Fig. 1-5,D) This common name is applied to Pandanus spiralis and other species in the genus of the Pandanaceae family. Native to Australia and tropical Asia, its morphology somewhat resembles the branching Hyphaene palm. The screw palmís sword-like leaves form tufted crowns and the tree bears large pineapple-like fruits. Where Pandanus spp. occur, leaves are widely used for weaving mats, baskets and so on.
Palm fern. This plant is indeed a fern and not a palm. Its scientific name is Cyathea cunninghamii, originating from New Zealand and Australia, and it is a member of the tree-fern family, Cyatheaceae. This tall, slender plant has a single stem and pinnate leaves somewhat resembling those of a true palm.
Palm grass. The scientific name for this perennial Asian grass, Setaria palmifolia, is an indication that the entire leaves resemble those of certain palms. It is classified as belonging to the grass family, Gramineae/Poaceae.
Panama hat palm. This plant is a monocot like a palm but is a member of the Cyclanthaceae family and bears the binomial Carludovica palmata. With its palmate leaf, this stemless understory plant of the lowland forests of Central and South America, is often mistaken for a true palm. The common name comes from the use of the fiber of young leaves to weave high quality hats.
The purpose of this report is to provide basic information about palms
as non-timber forest products. The prospective audience includes forestry
technicians, international development workers, policy makers and international
conservation and development agencies. Guiding principles of this report
are: 1) to identify and describe palm products; 2) to link the product
to the palm species being exploited as well as to the conservation status
of that species; 3) to give citations within the technical literature to
more detailed sources of information if needed. Strictly ornamental use
of palms is not considered in this report, except for a very few relevant
references. Through the use of this report, it will be possible to assess
the role palms and their products can play within integrated forestry,
agriculture, conservation and natural resource management activities.
Figure 1-5. False Palms. A. The travellerís palm (Ravenala madagascariensis).
B. The sago palm (Cycas revoluta). C. The palm lily or ti palm (Cordyline
spp.). D. The screw palm (Pandanus spiralis).
This report concentrates on the tropics where the great majority of palm species are to be found. In a few instances, where it seems practical, information is included on native palms which occur beyond the tropics. Inasmuch as this report deals with forest products and the impacts of their exploitation, the focus is on native palms as they occur in the wild. Exotic palm species are of course present throughout the tropics, being grown casually as ornamental species or on plantations as in the case of major economic species. In a few instances, exotic palms have become naturalized and are able to grow on their own in their new habitat. Domesticated palms are discussed because of the examples they represent in terms of the ways in which their products have been used and developed. To achieve full coverage of palm products, palm stem wood is included in this report, despite the "non-wood" designation.
Three distinct parts constitute this report. Part one consists of the first three chapters. This first chapter provides a general introduction to palms as the diverse group of plants they represent. It is followed by an examination of the ways in which historically human societies have made use of palm products. Case studies of indigenous palm use and short summaries of the characteristics of the major domesticated palms are included. Chapter 3 focuses on contemporary palm products and provides a means to classify products and their processing requirements.
Part two provides regional examinations of utilized native palms in Asia, the Pacific, Latin America and Africa. The same general approach is used in Chapters 4-7: to consider native utilized species on the basis of their conservation status in the wild, either "threatened" or "non-threatened." Selected local palm names are included in the tables. Chapter 8 attempts a pantropical review of palm products and addresses the issue of which species have the most development potential and how a coordinated effort could be beneficial for sustainable palm utilization and development.
The final third of the report includes a section devoted to an assemblage of tables on the technical properties of palm products. Other sections consists of a lengthy list of cited references, a compilation of other palm information sources and finally a directory of palm specialists.
1/ Genera Palmarum, is the best source of general information about the palm family to the generic level. It also defines technical terms associated with describing palms and provides illustrative line drawings and photographs. However, it contains little in the way of detailed information about individual palm species.