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On The Amazonian Trail of Useful Plants.
"What magnificent vegetation!" wrote Alexander yon Humboldt, the great plant geographer who was one of the first to study Latin America's profuse flora in detail. "We have been running around like a pair of fools: for the first three days we weren't able to concentrate on anything..." he wrote to a friend from South America in 1799.

I could understand von Humboldt's excitement about the tropical rain forest. I was deep in the Amazon forest at the Amazonian Center for environmental Education and Research (ACEER), which administers the Amazonian Biosphere Reserve, a 250,000 acre tract near the Napo River, a tributary of the Amazon, about 75 miles from Iquitos, Peru.

I had just attended a week's workshop on medicinal Amazonian plants taught by USDA ethnobotanist Dr. James Duke, for physicians, botanists, and others (HerbalGram. Number 31, pp. 32-33). Then, working with Shaman Don Antonio Montero, native curandero, or healer, and expert tree climber, I went into the rainforest to collect and photograph the plants and trees on ACEER's unique "Useful Plant Trail" to illustrate a brochure for future visitors.(*)

Possibly the only self-guiding trail in Amazonia, the Useful Plant Trail makes a 2-kilometer (1 1/4-mile) loop through some of the most diverse rainforest in the world, home to about 300 different species of woody plants per hectare (2.5 acres). The trail had been laid out by Dr. James Duke, botanist Rodolfo Vasquez, Teresa Wood and Paul Donahue of ACEER, and my co-worker, Don Antonio, whose broad ethnobotanical knowledge began back in his childhood, starting at 13 when he worked two years as a rubber tapper.

The plants and trees were tagged and numbered along the rustic trail; some of the trees were over 100 feet tall with spreading root buttresses 6 or 8 feet across to challenge the climber. To get a spray of leaves to photograph, Antonio used rock-climbing gear and techniques learned at ACEER that left no wounds on the bark. Sometimes enveloped in a cloud of stingless, but aggravating, sweat bees, he would pull on a headnet and continue working his way up, stepping in nylon loops, sliding foot by foot up the trunk. After he reached a branch, down would parachute a sprig of leaves for me.

One beautiful compound leaf reeked of garlic as I photographed it in the tropical sun. This was Cedrela odorata L. Meliaceae of the mahogany family, locally called cedro colorado, whose bitter bark is used as a remedy for colds, fever, diarrhea, and orchitis. Like some trees in Amazonia whose bark, leaves, or fruit are used medicinally, its wood -- richly colored and mahogany-like -- is also in high demand in the timber trade.

This is the dilemma brought home by ACEER's Useful Plant Trail: of the 35,000 to 80,000 species of higher plants estimated to grow in Amazonia, only a tiny fraction have been investigated for their medicinal or chemical potential. Yet destruction of the forest proceeds rapidly in Amazonia -- for timber, for firewood, for edible tree products such as palm hearts, for farms and ranches -- before we even know what plants it harbors and their possible uses.

For a week we walked the trail every day, collecting and phototographing leaves from about 45 tagged and identified plants and trees. Though these are only a small portion(**) of the plants used by local Indians and the ribere¤os -- the people of mixed Indian and European blood who live along the rivers -- the trail gives a visitor a representative sample and shows how plants enter into every facet of Amazonian life.

Vines or lianas are commonplace in the Amazonian forest. Curarea toxicofera, a vine with a contorted, flat stem, is one of several labeled vines on the trail yielding curate, a common dart poison, which is the source of d-tubocurarine, a pre-surgical muscle relaxant. Close by on the trail grows the means for delivering curare to the hunted animal. This is Inayuga, a small palm (Sheelea insignis), whose broomstick-size woody stems can be split into darts. The local Yagua Indians sharpen them by scraping them with a jawbone of piranha teeth, and then dipping them in curare and drying them for the next hunt.

A number of trees on the trail have latex-like sap that often indicates medicinal properties. I tasted the pleasantly sweet latex of leche caspi, or "milk tree," Couma macrocarpa, used to counter an amoebic diarrhea and extract botfly larvae from the skin. Its tasty fruits are very popular in nearby Iquitos and its rubber-like latex was formerly used in gum manufacture and is still exported as gutta percha for golf balls. Another tree, this one with orange latex, in the St. John's Wort family, Vismia angusta, is used locally to treat ringworm fungi and herpes of the lips by the Tikuna Indians of Colombia.

On a hilly part of the trail stands yet another mahogany relative, called Andiroba, Carape guianensis, a tree that has both excellent cabinet wood and a bark that is used to combat fever, worms, sores, and dermatitis. Andiroba fruits also yield an oil that, in Brazil, is ingested for coughs.

Not far from the Andiroba is one of the trees from a large tropical family, Bignoniaceae (represented in temperate North America by the Catalpa tree) being depleted near Iquitos by overcollecting for medicinal use. This is Tahuari, or Tabebuia incana, one of the many species of Tabebuia sold in the U.S. for cancer and yeast infections under such names as Ipe roxo, Lapacho, and Pau d'arco (bow tree). The compound it contains, lapachol, was studied by the National Cancer- Institute in the 1960s and found to be active against tumors in the lab but toxic in human trials due to the high doses necessary for effectiveness.

In the same family as Tabebuia and also threatened by over-collection is Clave huasco or the clove scented "clove-vine." Containing the chemical eugenol and useful for relieving toothache, it grows over the trail and can be identified by its opposite, compound leaves, forming the "cross" of the Croossvine family, or Bignoniacea. There is also a cross in the cross section of the stem.

As I walked the leaf-littered rainforest trail, I often noticed an oval seed with a red "aril," or seed coat, on the ground. Don Antonio pointed out that these are the seeds from a member of the nutmeg family, Virola pavonis, locally called cumala blanca, a tree whose genus is one of the main sources of hallucinogens in South America. The active alkaloid, tryptamine, is contained in the tree's inner bark, which is dried, toasted, powdered, and taken as snuff.

Some of the most beautiful leaves on the trail belong to a very useful Himatanthus sucuuba, known locally as Bellaco caspi. This is another tree with white latex that is plastered onto tumors, hernias, and slow-healing wounds. It is also used for worms and to suffocate subdermal botfly larvae. Tea made from the bark is used for coughs and fevers.

Palms are very common in Amazonia and provide a cornucopia of building materials and foods. The thatched houses on stilts of the ribere¤os, so commonly seen along the rivers, are often built with flexible floors made from the slatted trunks of two palms that grow along the trail on "stilt" roots, cashapona (Socratea exorrhiza) and huacrapona (Iriartea deltoidea). Roofs are thatched with irapay, a palm that grows just head-high and is easy to harvest with a machete. You can see this same beautifully woven thatch on the roofs of the river boats that bring ecotourists to ACEER and the ExplorNapo lodge.

Ten or more kinds of plants may go into construction of an Amazonian house. Many like ExplorNapo lodge near ACEER, are built entirely without nails, and are tied together with the bark of atadijo, or the dangling aerial roots of huambe or itininga, two of the 275 kinds of Philodendron in Amazonia, both of which can be seen on the trail.

As we completed our week's work. Antonio and I came to one of Amazonia's most useful palms, huasai (Euterpe precatoria), near the trail's end. Its edible heart, called chonta, is a favorite in salads, but, unfortunately, comprises only five percent of the felled tree.

"This palm is being exterminated in practically the whole rainforest," Don Antonio said. "In Iquitos there is a factors that operates night and day canning chonta palm hearts for export. They haul these palms down all the Amazon tributaries just to feed this factory. But, in a few years, they'll probably have to close it as they run out huasai."

Refreshing beverages are made from fruits of several Amazonian palms, and huasai is no exception. A tea is also brewed from the roots and used for treating painful menstruation and venereal diseases. And, like several of the palms, the rotting trunk serves as a nursery for two-inch-long palm grubs called suri (Rhynchophorus palmarum), that are eaten by the ribere¤os and regularly sold in the Iquitos market. Along with other curious types in Jim Duke's medicinal plant course, I had a chance to taste these grubs, fried in their own plentiful fat and lightly salted. The verdict was a lot like fried egg white!

The last day, after we had completed the climbing and photography, I walked the whole trail with Antonio. I tape-recorded his in-depth comments (which took half a day) about the uses of all 45 plants and trees. When I considered that five or six times this many species are sometimes found on a single hectare of this Amazonian forest. I gained some real perspective on the magnitude of the problem.

Not only do we need to learn much more about the thousands of plants yet to be investigated, both from people close to the forest like Antonio as well as scientists, but Amazonian countries somehow need to stem the wholesale forest destruction and elimination of certain tree species while still meeting economic needs of the ribere¤o population. Ways to do this might include development of agro-forestry plantations and creation of "extractive reserves."

Fortunately, visitors to the Useful Plant Trail at non-profit ACEER will not only learn much about biological diversity of this extraordinary region, but will also help finance research about this rainforest ecosystem and also about ways to provide environmental and economic benefits to the local inhabitant, of the Amazon Biosphere Reserve.


(*) Copies of the four-color Useful Plant Trail Guide (Item #408) and a video (Item #801) of the trail will be published and produced by ABC. Call: 800/373-7105 or write to ABC, P. O. Box 201660, Austin, TX 78720-1660, or FAX 512/331-1924.

(**) The most complete compilation is the Amazonian Ethnobotanical Dictionary, by James A. Duke and Rodolfo Vasquez, CRC Press, Boca Raton, Florida, soon to be available from ABC Books, Item #B071. See page 47.

Article copyright American Botanical Council.


By Jay Hutchinson