Puerto Rican giant hibiscus, Thespesia grandiflora. Carolina, north-eastern Puerto Rico.

Trees of Life

CLASS MAGNOLIOPSIDA: THE DICOTYLEDONS

    By far, most living flowering plants are dicots. Their seeds are divided into two sections (usually identical halves, like the valves of a clam's shell) with the embryo located at one end between them, and their leaves possess a net-like system of of veins through which sap runs, bringing nutrients to the cells. The flower parts of dicots exist in multiples of four or five. The group is paraphyletic and, thus, are not a true natural group, from a systematic standpoint.

Family Acanthaceae

    This is a family that includes several genera of plants with tubular flowers designed to be pollinated by hummingbirds, butterflies, and moths, all of which can reach the nectar with their long bills or proboscii.

Drejerella jamaicensis. Barbecue Botton, north-central Jamaica.
Tubular flowers like these are often pollinated by hummingbirds, which can probe them with their long beaks and tongues.

Justicia carthaginensis.

Near Great Pond, southern Saint Croix, United States Virgin Islands.

Justicia adhotoda. Blue and John Crow Mountains National Park, east-central Jamaica.

Ruellia coccinea.

First photograph: El Yunque National Forest, north-eastern Puerto Rico.

Second photograph: Maricao State Forest, western Puerto Rico.

Ruellia tuberosa. Pinones State Forest, north-eastern Puerto Rico.

Ruellia elegans. Blue Mountains, east-central Jamaica.

Ruellia brittoniana. Mayaguez, western Puerto Rico.

Oplonia spinosa. Guajataca, north-western Puerto Rico.

A common shrub or small tree of karstic and serpentien forests in several Caribbean islands.

Siphonoglossa sessilis. Camuy, north-western Puerto Rico.

Odontonema nitidum. Grant Etang National Park, Central Grenada, Lesser Antilles.

Family Anacardiaceae

    This family of shrubs and trees is a pantropical group of nearly 600 species. One of the best known is Mangifera indica: the mango tree, from south-eastern Asia. A few West Indian members of the family bear edible fruits or seeds (the cashew, Anacardium occidentale, is one of them) but many also produce a poisonous sap or latex, capable of causing severe skin reactions in some people.

    Cashews produce poisonous seeds that dissuade many animals from eating, and thus destroying, them. However, they still entice animals to disperse their seeds by producing a "pseudo-fruit". As the seeds mature, their stems become red, fleshy, and edible. It is not a true fruit, since the seeds remain on its outside. However, the result is the same: an animal will tear the sweet-tasting structure, with its dangling seed, consume it, and then drop the seed in some suitable place for it to develop into a new plant. Of course, humans often defeat the plant by roasting the nuts in order to destroy the toxins and make them edible, as well.

Poison ash, Comocladia dodonaea. Guanica State Forest, south-western Puerto Rico..

This relative of the mango can cause severe dermatitis in people who come in contact with the poisonous thorns on its leaves.

Another species of poison ash, Comocladia glabra.

Camuy Caverns Park, Camuy, north-western Puerto Rico.

Fruits of Comocladia glabra.

Maricao State Forest, western Puerto Rico.

Pseudo-fruit and seedpod of Anacardium occidentale. Anse Ger, south-western Saint Lucia, Lesser Antilles.

This is the well-known cashew. Like many members of its family this plant is dangerously toxic.

The seeds need to be roasted before they become edible.

The edible fruits of Spondias mombin, eaten by both animals and humans in the Caribbean.

Kingstown, south-western Saint Vincent, Saint Vincent and the Grenadines, Lesser Antilles.

Family Annonaceae

    Some tropical trees bear their flowers and fruits on their trunks and branches instead of growing them in terminal inflorescences. This spatial arrangement makes it easier for the flowers to be pollinated, and for the fruits to be eaten (and the seeds dispersed) by flying animals.

    One family of plants with some members that show this characteristic is Annonaceae, which includes the soursop and other Neotropical trees of the genus Annona. Several species of the genus produce edible fruits sought after by both animals and humans alike.

Common soursop, Annona muricata. Quebradillas, north-western Puerto Rico.

Annona reticulata. Cabrits National Park, north-western Dominica, Lesser Antilles.

Family Apocynaceae

    Many of these plants possess deadly toxins. However, they are notorious for being the larval food plant of a number of insects. Particularly, some sphynxid moths' caterpillars incorporate the plants' alkaloids to their own tissues, thus becoming toxic themselves.

    Several species of Plumeria are found in the Caribbean. They usually have large, colorful flowers with a sweet fragrance.

Plumeria alba. Sierra Bermeja, south-western Puerto Rico.

Forsteronia portoricensis. Maricao State Forest, western Puerto Rico.

Thevetia peruviana. Bahoruco National Park, south-western Dominican Republic, Hispaniola.

Family Asclepiadaceae

    Milkweeds and many of their relations produce a toxic white latex that has earned them their common names. Asclepias curassavica is common in the Antilles, and is known to be the main food source for the (also toxic) butterflies of the genus Danaus (the monarch and its relatives).

    Several members of the family develop their seeds in dry pods. The seeds often have fluffy tufts of hair that allow them to be dispersed by the wind.

Scarlet milkweed, Asclepias curassavica.

Carite State Forest, east-central Puerto Rico.

Opened seed pod of Asclepias curassavica. Florida, central Puerto Rico.

Several species of plants in diverse families produce seeds with long, fluffy hairs that help them to disperse by wind action.

White milkweed, Asclepias nivea. Florida, central Puerto Rico.

Matelea maritima. Guanica State Forest, south-western Puerto Rico.

Unlike the previous species, this is a woody vine.

Metastelma parviflorum. Caja de Muerto Nature Reserve, off southern Puerto Rico.

Metastelma sp. Mount Hartman Bay, south-western Grenada, Lesser Antilles.

Family Asteraceae

    The largest family of flowering chlorobionts on planet Earth. Containing more than 1000 genera and 30000 species in every island bank and continent except Antarctica, it is rivaled in numbers only by orchids.

    Members of this Cosmopolitan group are characterized by the structure of their inflorescences. In most cases, an asteracean "flower" is actually a multitude of tiny flowers placed together in a "head" ("capitula") surrounded by whorls of petal-like bracts. Some species lack these bracts, and all one sees is the small capitula.

    Some asteraceans, like the sunflower and lettuce, have great economic importance as crops.

Bidens alba. Humacao, south-eastern Puerto Rico.

In this typical asteracean, the white bracts resembling petals surround a head of tiny, yellow,  flowers.

The flowers of Sphagneticola trilobata, surrounded by a whorl of bracts. El Yunque National Forest, north-eastern Puerto Rico.

Vernonia borinquensis. Susua State Forest, south-westernl Puerto Rico.

Asteracean flowers, species undetermined. Bahoruco National Park, south-western Dominican Republic, Hispaniola.

Asteracean flowers, species undetermined. Barbecue Bottom, north-central Jamaica.

Gundlachia corymbosa. Quebradillas, north-western Puerto Rico.

Emilia fosbergii. Aguas Buenas, east-central Puerto Rico.

Seeds of Emilia fosbergii. Guilarte State Forest, west-central Puerto Rico.

Pluchea odorata. Carolina, north-eastern Puerto Rico.

Erigeron bellioides. El Yunque National Forest, north-eastern Puerto Rico.

This is one of the smallest of asteraceans. The flowers are about two millimeters in diameter.

Verbesina alata. Quebradillas, north-western Puerto Rico.

Wedelia lanceolata. Guanica State Forest, south-western Puerto Rico.

Wedelia fruticosa. Sierra Bermeja, south-western Puerto Rico.

Sphagneticola trilobata. El Yunque National Forest, north-eastern Puerto Rico.

Chrysantellium americana. Blue and John Crow Mountains National Park, east-central Jamaica.

Eclipta prostrata. Rio Abajo State Forest, central Puerto Rico.

Family Bataceae

    This is a group composed only of the genus Batis: the saltworts. Batis maritima is very common in Caribbean seashores. A halophyte, this plant thrives in salty soils near mangrove swamps and beaches. The only other species in the genus is found in the Australasian region.

    In some places, people add the succulent, salty leaves to salads.

Saltwort, Batis maritima.

First photograph: Anegada, British Virgin Islands.

Second photograph: Cabo Rojo State Forest, south-western Puerto Rico.

Saltwort, Batis maritima. Neiba Valley, south-western Dominican Republic, Hispaniola.

These plants form extensive aggregations in some regions of the West Indies.

Family Begoniaceae

    Species of Begonia usually are succulent plants of humid habitats. Several varieties are cultivated as ornamentals in many parts of the World, and have been hybridized to produce plants much larger than their wild counterparts.

Two color morphs of Begonia decandra. Carite State Forest, east-central Puerto Rico.

Begonia oblicua. Eggleston, south-central Dominica, Lesser Antilles.

Begonia humilis. Blue Mountains, east-central Jamaica.

Begonia vicentina. Grand Etang National Park, central Grenada, Lesser Antilles.

Begonia pensilis. Mount Soufriere, northern Saint Vincent, Saint Vincent and the Grenadines, Lesser Antilles.

Begonia sp. Port Antonio, Jamaica.

Family Bignonaceae

    These are shrubs and trees with usually tubular or trumpet-shaped flowers, characterized in the Antilles by trees like Crescentia calabashes and Tabebuia "cedars".

    Although not edible, calabashes figured in pre-Columbian West Indian cultures as freshwater vessels used during long journeys among islands. They are also dried out and used as percussion musical instruments to this day.

Puerto Rican calabash, Crescentia portoricensis. Quebradillas, north-western Puerto Rico.

This is a rare and endangered species of the mesic forests of the island.

Crescentia sp. Eggleston, south-central Dominica, Lesser Antilles.

Calabash, Crescentia linearifolia. Quebradillas, north-western Puerto Rico.

    Other members of these family are the Tabebuia trees and shrubs that are common in the Neotropics. Several species are endemic to the Antilles and some bloom spectacularly during certain seasons. Their red, pink, or yellow flowers cover the ground around them after they fall off.

Flowers of Tabebuia karsensis. Maricao State Forest, western Puerto Rico.

Tabebuia haemantha.

First photograph: Susua State Forest, south-western Puerto Rico.

Second photograph: Maricao State Forest, western Puerto Rico.

White cedar flowers, Tabebuia heterophylla.

First photograph: Carolina, north-eastern Puerto Rico.

Second photograph: Parque Central, San Juan, north-eastern Puerto Rico.

Third photograph: Bahia Ballena Nature Reserve, south-western Puerto Rico.

Tabebuia sp. Maricao State Forest, western Puerto Rico.

Tabebuia rigida. El Yunque National Forest, north-eastern Puerto Rico.

Endemic to the cloud forests of the Luquillo Mountain Range in that island.

    Finally, some of these plants are vines, like Distictis and Schlegelia common in xeric and mesic forests, respectively.

Distictis lactiflora. Sierra Bermeja, south-western Puerto Rico.

The large flowers of this plant are similar to those of the related Macfadyena vines.

Another bignonacean vine: Schlegelia brachyantha.

First two photographs: Carite State Forest, east-central Puerto Rico.

Last photograph: Maricao State Forest, western Puerto Rico.

Macfadyena unguis-cati. Mount Sage, west-central Tortola, British Virgin Islands.

Family Bombacaceae

    The balsa-wood family is represented in the West Indies by trees like the kapok, Ceiba pentandra. This is a large tree with buttress roots that help it withstand its own weight, especially during hurricanes. Young kapoks have their trunks covered in large thorns that fall off at the plant matures.

    On regards to volume, some Antillean Ceiba are among the most massive terrestrial organisms in the region and may be a few thousand years old. Sadly, many of these giants were cut down long ago for their wood.

Family Boraginaceae

    This group is Cosmopolitan in distribution. Some of the Antillean species like, those of Bourreria, produce small, delicate flowers common along trails in humid and dry forests. The bright orange or red flowers of some Cordia trees are avidly fed upon by some Antillean hummingbirds.

Flowers and fruit of pigeon berry, Bourreria succulenta.

First photograph from Caneel Trail, Virgin Islands National Park, Saint John, United States Virgin islands.

Second photograph from the Guanica State Forest, south-western Puerto Rico.

Bourreria dominguensis. Carolina, north-eastern Puerto Rico.

Hound's tooth, Cynoglossum sp.

Bahoruco National Park, south-western Dominican Republic, Hispaniola.

Cordia dentata. Sandy Point National Wildlife Refuge, south-western Saint Croix, United States Virgin Islands.

Flowers of the trumpet tree, Cordia sebestena. Camp Santiago, Salinas, south-eastern Puerto Rico.

Cordia polycephala. Carite State Forest, east-central Puerto Rico.

Cordia lima. Susua State Forest, south-western Puerto Rico.

Heliotropium angiospermum. Guanica State Forest, south-western Puerto Rico.

Family Burseraceae

    The frankincense family is represented in the West Indies by Bursera simaruba, a tree of xeric areas which reddish bark is shed in thin layers. This has earned it the local name name of "tourist tree", reminiscing the way unwary visitors to the Caribbean spend too much under the sun, paying the consequences later as their skins peel off.

    Another Antillean species of this group is the "tabonuco" or "gommier", belonging to the monotypic genus Dacryodes of the Lesser Antilles and northwards to Puerto Rico. Its flammable resin was used by Amerindian tribes to coat torches. Because of the very pungent, "chemical" smell of their gum these organisms are called "turpentine trees", in some islands. Dacryodes excelsa is one of the tallest and most massive trees in the Caribbean, and is one of the main components of the rain forests where it lives.

The bark of Bursera simaruba peels away in thin layers as the organism grows.

Little Dix Bay, Virgin Gorda, British Virgin Islands.

Fruits of Bursera simaruba.

Hurricane Hole, Virgin Islands National Park, Saint John, United States Virgin Islands.

The massive tree trunks of Dacryodes excelsa become highways at night, when frogs, insects, centipedes, and other rain forests organisms commute to and from

the canopy. These magnificent giants of more than 30 meters in height and with trunks sometimes reaching 3 meters in diameter, are found in the Lesser Antilles

from Grenada north to Montserrat, and then reappears in Puerto Rico. Their aromatic, flammable sap has earned them the English name of "turpentine trees",

a name shared in some islands with another member of its same family, Bursera simaruba (above ).

Carite State Forest, east-central Puerto Rico.

Family Cactaceae

    Cacti belong to an almost exclusively American family (only one species, shown below, is found in the Old World). By far, most species of cacti live in dry regions, like deserts, savannas, and xeric forests. Their thorns are modified stems that fulfill the purpose of deterring their predators. While some species possess leaves, it is in the upper cell layers of their trunks and branches where photosynthesis takes place.

    The relatively few species of cacti of mesic habitats seldom have thorns, and might live as epiphytes on the large trees of humid and rain forests. Rhipsalis cacti resemble shaggy green beards as they hand from trees' branches.

Family Campanulaceae

    This a group of plants of temperate, subtropical, and montane tropical regions. They are represented in the Antilles by genera like Lobelia. Plants of this and related genera are dangerously poisonous if their parts of sap are ingested.

Puerto Rican lobelia, Lobelia portoricensis. El Yunque National Forest, north-eastern Puerto Rico.

Lobelia acuminata. Barbecue Bottom Road, north-central Jamaica.

Lobelia cirsifolia. Grand Etang National Park, central Grenada, Lesser Antilles.

Lobelia brigittalis. Mount Soufriere, northern Saint Vincent, Saint Vincent and the Grenadines, Lesser Antilles.

The highly poisonous Isotoma longiflora. Barbecue Bottom, north-central Jamaica.

Centropogon sp. Constantine, south-central Grenada, Lesser Antilles.

Family Capparaceae

    The Pantropical family of about 800 species is represented in the region by genera like Cleome and Capparis. Although some Old World members of this genus have been introduced into the West Indies, other species are native to the region.

Capparis indica. Guanica State Forest, south-western Puerto Rico.

A Mediterranean member of the genus, the caper (Capparis spinosa), is widely used in European-style cuisine.

Capparis cynophallophora. Guana Island, British Virgin Islands.

Capparis flexuosa. Guana Island, British Virgin Islands.

The beautiful spider flowers of Cleome spinosa.

Bonne Resolution, central Saint Thomas, United States Virgin Islands.

Flower of Cleome aculeata, during anthesis. San Juan, north-eastern Puerto Rico.

Family Caricaceae

    This small Neotropical family includes several trees used by man as food sources. Some of the genus Carica are cultivated for that purpose. Their melon-like fruits are borne near the top of their usually un-branched trunks. Alike relished by man and animals (especially frugivorous birds) the yellow-to-red flesh of its fruits has a sweet smell and taste. The juice is often used as meat tenderizer, since it contains an enzyme called "papaine" with dissolves connective tissue in animal flesh.

Family Cecropiaceae

    The trumpet tree family is an American group distributed mainly in the Neotropics. They have branches divided in septa filled with spongy pith. Fast growing plants, they are among the first pioneers to invade new areas like landslides and clearings created by fire and storms. The Antillean trumpet tree, Cecropia schreberiana, is a West Indian endemic commonly seen in montane humid and rain forests in all the Greater and Lesser Antilles. Until recently considered conspecific with C. peltata of the continental Neotropics, its huge leaves have silvery undersides and a coarse, sandpaper-like feel to the touch.

The flower and fruit stalks of Crecropia schreberiana are positioned in a way that makes it easy for bats and birds that feed on them.

El Yunque National Forest, north-eastern Puerto Rico.

Family Celastraceae

    Plants like the spoon tree, Cassine xylocarpa, and its Crossopetalum relatives inhabit coastal forests and xeric inland forests of the West Indies. They form part of the understory of their habitats. The fruits of many of these shrubs and trees are dangerously poisonous.

Cassine xylocarpum. Anegada, British Virgin Islands.

Crossopetalum rhacoma.

First photograph: Carolina, north-eastern Puerto Rico.

Second photograph: Sandy Point National Wildlife Refuge, south-western Saint Croix, United States Virgin Islands.

Family Chloranthaceae

    Some aromatic bushes and trees of this family are found in the highland forests of the Antilles. Species of Hedyosmum are typical of this group, there.

Hedyosmum arborescens. El Yunque National Forest, north-eastern Puerto Rico.

Family Chrysobalanaceae

    The genus Chrysobalanus is peculiar in having a disjunct distribution spanning the New and Old Worlds. C. icaco is widely distributed in the neotropical region, and is found as well in western Africa.

    The somewhat astringent fruits are edible, as are the nut-like seeds.

Flowers and fruit of the coco-plum, Chrysobalanus icaco.

First photograph: Sage Mountain National Park, west-central Tortola, British Virgin Islands.

Second photograph: Sandy Point National Wildlife Refuge, south-western Saint Croix, United States Virgin Islands.

Family Clusiaceae

    These trees or shrubs produce a yellowish, sticky sap, and possess coriaceous leaves. The rose-apples and related species, of the genus Clusia are shrubs or trees  found in humid and montane forests of the Antilles and tropical continental America. Some of the 150 species are stranglers. Their large, leathery leaves are so long-lived and resilient that in the past people used to write on them and use them like postcards.

Family Combretaceae

    This family includes some trees common in coastal areas of the West Indies, like the Conocarpus and Laguncularia "mangroves". Not being true mangroves, they nonetheless are adapted to saline soils. Other species are large trees of humid and rain forests.

    The huge tabular roots of Buchevania are a common sight in the montane forests of several islands. Other species, like Bucida buceras, are more common in xeric to sub-mesic regions. Strangely, the bark of Bucida trees is frequently covered in epiphytes, while that of other tree species nearby is not.

Buchevania capitata. Northern Forest Reserve, Dominica, Lesser Antilles.

Panicle of Bucida buceras, a common tree of the dryer regions of the Antilles.

Sierra Bermeja, south-western Puerto Rico.

Family Convolvulaceae

    This Cosmopolitan family is a group of twinning vines (sometimes shrubs or trees) usually producing a milky sap. They are represented in the West Indies by various genera. The most commonly seen of these might be the members of the genus Ipomoea. Many of these plants, and those of related genera (Convolvulus, Evolvulus, Jacquemontia, Merremia) produce beautiful but delicate and ephemeral flowers that bloom in in the early morning (sometimes at night) and progressively wither during the heat of the day. This characteristic has earned them the name of "morning glories". Several species have been domesticated and hybridized, and are found in gardens around the World.

Morning glory, Ipomoea indica. Windsor, north-central Jamaica.

Some members of this genus are valued as garden plants for their large, beautiful flowers.

As their common name implies, the flowers live for only one day. By the evening of the

same day they bloom, they wilt to nothing under the strong tropical sunlight.

Morning glory, Ipomoea repanda. El Yunque National Forest, north-eastern Puerto Rico.

Morning glory, Ipomoea steudelii.

First photograph: Susua State Forest, south-western Puerto Rico.

Second photograph: Guanica State Forest, south-western Puerto Rico

Morning glory, Merremia quinquefolia. Camuy, north-western Puerto Rico.

Morning glory, Merremia umbellata. Arecibo, northern Puerto Rico.

Morning glory, Merremia dissecta. Quebradillas, north-western Puerto Rico.

Jacquemontia solanifolia. Sandy Point National Wildlife Refuge, south-western Saint Croix, United States Virgin Islands.

Jacquemontia pentanthos. Guanica State Forest, south-western Puerto Rico.

Convolvulus nodiflorus. Sandy Point National Wildlife Refuge, south-western Saint Croix, United States Virgin Islands.

Family Cucurbitaceae

    Cucumbers, melons, watermelons, pumpkins, and other edible fruits cultivated by man belong to this cosmopolitan family. West Indian species are usually inedible and, like most members of the family are tendriled vines.

Melothria guadalupensis. Dorado, northern Puerto Rico.

Doyerea emetocathatartica.

First photograph: Blue and John Crow Mountains National Park, east-central Jamaica.

Next two photographs: Crown Mountain, central Saint Thomas, United States Virgin Islands.

Family Cuscutaceae

    This is a family of parasitic plants. Unusual in lacking chlorophyll, these vegetal vampires derive their nutrients by absorbing on the sap of other plants. Several species of Cuscuta are found in the Antilles, especially in xeric areas. Their flowers are inconspicuous and resemble tiny buds.

Cuscuta americana.

First two photographs: Virgin Islands National Park, Saint John, United States Virgin Islands.

Family Cyrillaceae

    The monotypic genus Cyrilla represents this group in the West Indies. It is found from the south-eastern Unites States to northern South America. Cyrilla racemifolia is one of the main components of Antillean montane rain forests. Interestingly, this plant is but a bush in temperate latitudes, but grows as a tree in the tropics. The common trait of all populations is that they need waterlogged soils to thrive: flooded ground in the temperate regions (hence its common name), or rain-soaked soils in the Antillean mountains.

    As an interesting note, a certain swamp cyrilla in the Luquillo Mountains of Puerto Rico may be 3000 years old.

Swamp cyrilla, Cyrilla racemifolia. Known as "palo colorado" ("red tree") in Puerto Rico, this is a plant of very wet habitats.

A shrub typical of swamps and bogs in continental North America, it attains a far larger, tree size on the waterlogged soils of Greater Antillean

montane rain and cloud forests. El Yunque National Forest, north-eastern Puerto Rico.

Family Ebenaceae

    This is a family of two genera found in both hemispheres. Dyospiros is Pantropical genus of about 250 species, with some entering temperate latitudes. Some forms are harvested for their wood, hard and dark in color, apt to be polished into beautiful shapes.

Puerto Rican ebony, Diospyros sintenisii.

Camuy, north-western Puerto Rico.

Family Eleocarpaceae

    Some members of this family are gigantic trees of the Antillean rain forests. Their buttress roots can be several times higher than a man, and form natural mazes covered in epiphytes.

The enormous buttress roots of Sloanea caribaea. Northern Forest Reserve, Dominica, Lesser Antilles.

The rotten hollow in the photograph on the left is tall and wide enough for a grown man to walk through it.

Bole of Sloanea dentata. Northern Forest Reserve, Dominica, Lesser Antilles.

Family Ericaceae

    The large family Ericaeae is cosmopolitan in distribution. Tropical species are mostly restricted to cool montane habitats. members of the small genus Gonocalyx are vines that climb up trees in cloud forests. There are six species in Hispaniola, Puerto Rico, Dominica, Martinique, and Colombia. Of the two endemic Puerto Rican species, Gonocalyx concolor is found only in the highest reaches of the Cayey Mountain Range, in the south-eastern quadrant of the island.

Gonocalyx concolor. Carite State Forest, east-central Puerto Rico.

Gonocalyx portoricensis. El Yunque National Forest, north-eastern Puerto Rico.

Vaccinium racemosum. Carite State Forest, east central Puerto Rico.

Family Erythroxylaceae

    This family includes one of the most famous - or infamous - plants on Earth: the South American coca shrub, Erythroxylon coca, from which the narcotic cocaine is derived. West Indian members of the genus do not produce high quantities of the alkaloid which gives rise to the drug. Thus, they are not attractive to the illegal drug market.

West Indian coca shrub, Erythroxylum brevipes. Cabo Rojo State Forest, south-western Puerto Rico.

Erythroxylum aerolatum. Guanica State Forest, south-western Puerto Rico.

Family Euphorbiaceae

    These are herbs, shrubs, or trees many of which produce a milky, sticky latex. In some species, this substance produces a severe dermatitis if it comes in contact with the skin, and the leaves and fruits of a few are deadly poisonous, if ingested.

Euphorbia cyathophora. Ciales, central Puerto Rico.

Chamaesyce articulata. Susua State Forest, south-western Puerto Rico.

Family Fabaceae

    The legumes form a large and varied family of plants with about 17000 species described to date. They can be herbs, shrubs, lianas, or trees, and are characterized mainly by the kind of fruit they produce. When mature, this is usually a dry, elongated capsule containing from one to many seeds. Some genera, like Phaseolus, (kidney beans and their relatives) and Cajanus (pigeon beans) are important crop plants worldwide.

    The family is divided into three subfamilies, mainly distinguished among themselves by the structure of their flowers.

Subfamily Caesalpinioideae

    The flowers of this subfamily are zygomorphic. This means that the flowers are bilaterally symmetrical, and in such way can be divided into halves only along one plane.

Chamaecrista glandulosa. Florida, central Puerto Rico.

Hymenaea courbaril, tree and its fruits (a very large, woody legume). Caguas, east-central Puerto Rico.

Although this individual is young and small, this can become one of the largest native trees in the West Indies.

Bauhinia sp. Mount Hartman National Park, south-western Grenada, Lesser Antilles.

Subfamily Mimosoideae

    This subfamily is characterized by their actinomorphic flowers. This means that the flowers are radially symmetrical, like a star, in such a way that they can be dissected along any vertical plane passing through their centers to form two identical halves.

    Some species in this group are peculiar for being sensitive to mechanical disturbance. When touched, their leaves will immediately close along the central stem.

    The intricacies of this unusual phenomenon, quite rare in the plant world, are very different from those of the movements of animals, which are based on the bioelectrical mechanics of muscles (which no plant has). In the case of sensitive plants, like those of the genus Mimosa, the movement of the leaves are caused by touch-induced variations of water pressure inside the plant's tissues. The water pressure drops suddenly (similar to the way an air-filled balloon deflates) lessening the turgidity of the leaves' stems, and this causes them to fold upon themselves.

    The sudden movements of members of unrelated families, like some "carnivorous" plants, are due to a similar process.

Acacia retusa. Mount Hartman National Park, south-western Grenada, Lesser Antilles..

Sensitive plant (one of several species). This is Mimosa pudica. Carite State Forest, east-central Puerto Rico.

Neptunia plena. Carolina, north-eastern Puerto Rico.

Pithecellobium unguis-cati.

First two photographs: Camp Santiag