SCIENCE HAS DISCOVERED a tree that bears delicious fruit, kills bugs and fights cancer. Well, make that re-discovered, actually. The tree is the pawpaw, whose fruit was once a staple of Native Americans and a godsend to the mountain men and pioneers.

After generations of neglect, Asimina triloba has become one of the hottest plants in American horticulture because, beside its nutritious fruit, the tree's tissues have been found to contain powerful natural pesticides and fungicides and dozens of compounds that are extraordinarily effective against drug-resistant cancers.

Pawpaws, which are nearly as common as weeds around Washington, vary widely in the size and quality of fruit. They are ripening even as you read this, so get out there and get 'em. Neal Peterson, who's the pawpaw equivalent of Johnny Appleseed, says he's confident that there are better wild trees out there than any that have been selected and cultivated so far. "Anybody wandering in the woods is just as likely as a scientist to find a more perfect pawpaw," he says. "The treasure hunt is far from over."

Researchers at Kentucky State University are analyzing DNA from trees all over the country in an attempt to sort out the species' family tree, or genome, seeking to identify varieties that have outstanding qualities for food, pest control or medicine. Kentucky State's cooperating with a score of other schools in testing how various varieties grow in different climate zones and soil types. Purdue University researcher Jerry McLaughlin's team has identified more than twoscore potent anti-cancer compounds in pawpaw leaves and bark.

A member of the custard apple family, the pawpaw is a shapely tree with large, glossy, drooping leaves that turn bright yellow in fall. It can grow to 40 feet or more under ideal conditions, but Peterson top-prunes his to about six or seven feet, to promote bushy growth and keep the fruit within reach. Not the least of the pawpaw's virtues as both a fruit tree and an ornamental is that it doesn't require spraying against diseases and insects, and deer will not eat the fruit or foliage. Raccoons and opossums love them, and squirrels are also accused of stealing them, but that may be a bum rap. They haven't bothered mine.

Peterson is a former U.S. Department of Agriculture researcher with such a passion for pawpaws that this year he decided to return to his native West Virginia and become a full-time commercial grower. Experimental groves Peterson planted 20 years ago at University of Maryland agricultural research stations at Wye and Keedysville have become a principal source of promising varieties and have earned him the nickname Papa Pawpaw.

The plant is a tropical tree that has adapted itself to the temperate zone and grows wild in 26 eastern states, from Florida to southern Canada. There are hundreds of pawpaw trees on Roosevelt Island and thousands of them inside the Beltway, especially in public parks (which do not forbid picking fruit). Pawpaws propagate both from seed and by underground runners and tend to grow in large patches. They're found along the banks of nearly every local stream and also grow in dry uplands and deep woods. There are plenty of places around here where if you kick a tree, it's odds-on to be a pawpaw.

Although enthusiasts have long been selecting and cultivating superior wild fruits, the typical fate of a lovingly tended amateur orchard is to be neglected -- or bulldozed -- when the owner dies. Progress can be implacable: The Beltway paved over the pawpaw collection of famous botanist David Fairchild. But the tree is hardy enough to withstand neglect, and some historic varieties thought to be lost have been recovered from orchards that had reverted to brambles and forest.

"I think it will take about another 25 years to get the strengths and weaknesses of various varieties sorted out and to get breeding programs going," Peterson says. "But it's going to be fun all the way; we can have our fruit and eat it, too."

Consuming Passion

Cooking with pawpaws isn't a job, it's an adventure. Because the fruit has been all but ignored for a century, reliable recipes are rare. Only three of my two dozen wild-foods cookbooks even mention Asimina triloba, and then only in passing. "The Joy of Cooking," that old American standby, gives pawpaws a paltry paragraph.

"Native Harvests," praised by food critic Craig Claiborne as "the most intelligent and brilliantly researched book on the food of the American Indian," entirely ignores the pawpaw, which was a mainstay of the Native American tribes east of the Mississippi. They feasted on the fresh fruit each fall, used it as a binder and sweetener in pemmican and dried it into fruit leathers as a wintertime staple.

All of which is by way of saying that you're very likely to be the first on your block to mess with pawpaws and will be largely on your own. Not to worry. Pawpaw is a very adaptable and forgiving fruit (it's actually a berry, botanically speaking). The taste, though distinctive and penetrating, blends well with other flavors. It's as nutritious as apples, bananas or oranges, and you can be confident that the fruit has never been sprayed with pesticides.

If you do find printed pawpaw recipes, be skeptical. Most of those I've found plainly have been picked up and passed along by people who did not test the recipe and may never have even seen the fruit. Do not, for instance, add pawpaw pulp to Jell-O.

The easiest way to get started is by adding spoonfuls of pulp to a vanilla milkshake one at a time until the flavor suits you. When you think it's just right, blend in a fresh egg. The effect is a quantum jump in richness that demonstrates the pawpaw's affinity for eggs and dairy products. And it makes the point that a little pawpaw pulp goes a long way; too much of this big, round, mouth-filling and lingering flavor can cloy. A little pawpaw pulp adds zest and aroma to muffins, corn bread and nut breads. The frozen pulp, substituted for all or part of the pineapple, yields a dynamite pina colada.

When using wild pawpaws, be sure to taste the pulp before adding it to any recipe. Pawpaws vary in flavor and intensity much more than most fruits, so that a cup of pulp from a given tree might be too much or too little in a particular dish.

When preparing pulp for freezing, remove the seeds and puree the flesh in a blender with a little citric acid to improve the texture and retard oxidation. This also accentuates the shift of the frozen pulp's flavor from custard-like toward citrus-like. It keeps well if sealed in airtight plastic bags or containers.

The leading source of pawpaw recipes is "Cooking With Pawpaws," a pamphlet prepared by researchers Snake C. Jones of Kentucky State University and Desmond R. Layne, now of Clemson University, who is president of the nonprofit Pawpaw Foundation. It's out of print but has achieved electronic immortality on the Kentucky State home page: www.pawpaw.kysu.edu. But Jones emphasizes that while the recipes were sought from reliable sources, the university has not tested them. She says pawpaw pie seems to be the favorite among her colleagues.

I tried out the first three pie recipes from the Kentucky State Web site and served them to a couple of experts on historical cookery, Anne Chotzinoff Grossman and Lisa Grossman Thomas, authors of the hilarious and authoritative "Lobscouse & Spotted Dog" (W.W. Norton, 1997). Although the texture was rather soupy and my meringues were pitiful, the mother-daughter team praised the aroma and found the flavor rather bland but distinctive, with great potential. Grossman suggested "a soupcon of citrus, either lime or lemon, to punch it up a little and mute the sweetness." "I'd like to get these recipes alone with my spice rack," Thomas said. "This fruit calls for some subtle flavor enhancement, perhaps beginning with a very light dusting of allspice."

Pawpaw ice cream is the hit of the annual Athens, Ohio, Pawpaw Festival (Oct. 10 this year). James Gerhardt, executive chef of Louisville's five-star (AAA) Seelbach Hotel, uses pawpaws in ice cream, green tomato compote, chutney and other dishes in banquets emphasizing Kentucky's culinary heritage and the gustatory resources of the Ohio Valley, including bourbon-smoked spoonfish. He's also working on a pawpaw brandy.

My own favorite so far is a pawpaw jam developed over the course of 10 experimental batches. The final version, when served recently to members of a Smithsonian Associates tour at Water Ways Nursery in Lovettsville, Va., got at least one thumb up from all 20 guests, and raves from several. It's superb on buttered toast, biscuits, corn bread or muffins, and is an incomparable base for sauce venaison. It makes a distinctive, yea distinguished PB&J sandwich. But it tends to be reluctant to jell; it commonly takes days or weeks to set up, and sometimes never does. However, the taste is fine in any case, so depending on the consistency, I simply label "failed" batches as syrup or pawpaw butter. My best results have been achieved with "no sugar" powdered pectin.

2 cups pawpaw pulp

1 cup water

1 cup applesauce

2 cups apple juice

1/8 cup lime juice

5 cups sugar

1 or 2 packages powdered pectin

Stir the pulp and liquids together in a capacious pot and sift in the pectin, which will tend to clump, but never mind. Stirring frequently, bring the mixture to a full rolling boil (can't be stirred down) and stir in the sugar. Stirring constantly, bring the blend to a full boil again and boil hard for one minute. Immediately pour into jelly jars that are hot from the dishwasher, with lids that are hot from a simmering pot. When the jars can be handled, store them in a dark, cool place. If they don't jell, be patient; sometimes it takes as long as a week. If it never jells, what the hell, pour it over pancakes and pretend you did it on purpose.

The Pawpaw That Refreshes

The highest and best use of pawpaws is as fresh fruit eaten out of hand. A ripe pawpaw has a distinctive, perfumy odor and a texture similar to yogurt or custard. Simply slice it in half at the equator and squeeze or spoon out the pulp, which ranges from creamy white through buttery yellow to bright orange. Discreetly suck and spit out the large seeds.

The flavors can be amazingly complex and various, as demonstrated by a recent and informal alfresco tasting in the experimental grove at the University of Maryland agricultural research center at Wye. The comments ranged from "icky" through "excellent" to "ethereal." The flavors of a half-dozen fruits selected at random, when tasted around the family table, were described as "orange sherbet," "vanilla custard," "mango," "banana," "caramel," "tapioca," "flan" and "Dreamsicle." The only agreement was that a good pawpaw is very good indeed.

Unpredictability of flavor is one of the major problems of the infant pawpaw industry. Even old established varieties, or cultivars, vary wildly, partly because of local growing conditions but mainly because many strains have become mixed and/or misidentified.

Ripe fruit can be hard to find, unless you have your own secret pawpaw patch. Happily, this Sunday fresh pawpaws from one of Neal Peterson's research groves will be offered at the Dupont Circle farmers' market. Peterson, founder of the nonprofit Pawpaw Foundation and a tireless promoter of the fruit, is trying to alter the conventional wisdom among fruit growers, who generally consider pawpaws to be more trouble than they're worth. The fruit is unfamiliar to most customers, has a short shelf life and, not to put too fine a point on it, can be ugly as homemade sin. As pawpaws ripen, the skin tends to turn from bright greenish-yellow to a leathery and blotched brown or even black. A major goal of current research is to breed varieties that look good, ship well and last long.

The quality peaks when the fruit becomes slightly soft, about a day before it drops from the tree, according to pawpaw guru Peterson. Refrigerated, peak-picked fruit may keep for several weeks. Once it hits the ground, eat or freeze the pulp fast; it will last only a few days at most. Pawpaws can be picked slightly green and allowed to ripen at room temperature.

Various varieties mature from August to October, and the fruit of a given tree may ripen over a period of weeks. (So far this season someone has beaten me to every fruit in the dozen wild groves I've been monitoring in the Washington area. The pawpaw underground seems very efficient.)

One of the few bugs that bugs pawpaws is the strikingly beautiful zebra swallowtail butterfly, which has developed immunity to the pesticide compounds found in the plant's bark and leaves. The butterfly's caterpillars feed exclusively on pawpaws, but do no permanent damage. Most gardeners are happy to sacrifice a few leaves to attract such a gorgeous insect.

HOW TO GET THEM

Fresh Pawpaws will be on sale this Sunday and next Sunday at the Dupont Circle farmers' market. The fruit will be from pawpaw pioneer Neal Peterson's first experimental orchard. The market is at the Q Street entrance of the Dupont Circle Metro station.

Pawpaw Pleasures of Albany, Ohio, ships fresh fruit in season (August through October) and frozen pulp year-round. Call Chris Chmiel, 740/698-2124. Chmiel, apparently the only national commercial supplier, says he's shipped more than 5,000 pounds of pulp so far this year.

From the Ground Up

The best way to get a dependable supply of pawpaws is to plant your own. Grafted plants of known varieties, nurtured under ideal conditions, will dependably produce high-quality fruit.

If you can get them. Such is the demand for pawpaws in recent years that the going price is three or four times that of most other popular fruit trees. You want second-year plants, at least 18 inches high, and should expect to pay $18 to $45 apiece (pawpaws are not self-fertile, so you'll need to plant two different cultivars near each other).

Ask a pawpaw researcher to name his or her favorite variety and you're guaranteed to get waffling, but these seem to be on everybody's A list (the descriptions are from Kentucky State University's pawpaw project home page: www.pawpaw. kysu.edu):

Davis, selected from the wild in Michigan by well-known pawpaw searcher Corwin Davis in 1959. Produces four- to five-inch fruits with yellow flesh and large seeds. Keeps well in cold storage.

Overleese, selected in Jefferson County, Ill., by W.B. Ward in 1950. Fruit up to 12 ounces, with few seeds.

Rebecca's Gold, selected from Davis seed in 1974 by J. M. Riley. Fruit three to six ounces, kidney shaped, yellow flesh.

Sunflower, selected from the wilds of Kansas by Milo Gibson in 1970. Fruits up to nearly a pound, yellow skin, butter-colored flesh.

Taylor, selected by Davis in Michigan in 1968. Bears small fruit in clusters of up to seven, green skin with yellow flesh.

Wells, found wild in Salem, Ind., in 1960 by David Wells. Fruit up to 14 ounces, green skin, orange flesh.

Some of these varieties, plus selected wild seedlings, may be available from Water Ways Nursery in Lovettsville, Va. (540/822-5994; online catalogue at members.aol.com/ wwnursery), and Edible Landscaping in Afton, Va. (800/524-4156; online catalogue at www.eat-it.com). Many nurseries combine offerings at www.garden.com, but you don't know who your source will be. Michigan nurseries are generally knowledgeable about pawpaws, which are a regional favorite. Many West Coast nurseries offer hard-to-find varieties, but I've had some bad cross-country shipping experiences.

Surfing the Web searching for "pawpaw" can be useful and entertaining, but don't goof around too long. There is said to be a backlog of orders for more than 30,000 grafted plants, so order soon for spring delivery.