The Paw Paw Trees
Don Robinson
One of my favorite fall foods is the fruit of the paw paw tree that grows fairly profusely in places along the Potomac River basin, including the Cacapon River. They are not for everyone, my wife can't stand the taste, but I find a good fresh ripe paw paw to taste a bit like banana custard with a bit of mango added. She doesn't much care for mango either, so this may be a benchmark: if you don't like mango, don't fool with the paw paw. The paw paw tree, which bears the largest fruit native to North America, may also bear a new fruit for scientists. In fact Purdue University researcher Jerry McLaughlin, working with doctoral student Nicholas Oberlies, has found compounds in the bark of the tree that have shown preliminary success in fighting some drug-resistant cancers. McLaughlin, whose research group has identified more than 40 paw paw compounds with anti-cancer properties, discovered a series of the compounds, called Annonaceous acetogenins, that were capable of killing cancer cells.
Asiminas triloba grows from 30 to 35 feet high. This tree is the only 'custard apple' in the northern U.S. The paw paw produces many suckers from the roots, which tend to make a dense thicket. It is common to observe thickets of these trees with few or no fruits, because the trees generally do not self-pollinate, and the thicket may actually be one organism. The ovate leaves grow from 4 to 12 inches long and 2 to 4 inches wide. They have a sharp pointed tip and smooth edges. The leaves resemble the individual leaf part of the compound shagbark hickory but are not compound and come out alternately from the twig. On the top, the leaves are glossy and smooth and the undersides are lighter, sometimes slightly hairy. The flowers are produced in April in our area. They are reddish-purple and measure a little less than 2 inches across. The name triloba comes from the fact that there are three petals and three sepals in the flower parts. Bees show no interest in paw paw flowers. The task of pollenization is left to flies and beetles, who are often impeded by an amazing crab spider that lives in the blossom of the tree and is exactly the same color as the bloom. I examined one branch in Largent one time and found three of the spiders hiding in the blooms. Following pollination of the flowers, development of clusters of up to 5 or 6 short, fat, hard dull green fruits begins. Around the autumnal equinox, the fruits ripen, fading to lighter yellowish green when ripe, eventually turning purplish brown when over-ripe. They are not palatable until a gentle squeeze show them to be softening. The texture of the flesh resembles custard (hence the nickname 'custard apple') and is sweet and fragrant. An average fruit contains about 6 dark brown seeds about the size of butter beans. I put them in my mouth to suck off the sweet flesh before discarding or saving for planting. I know people who eat the skins as well, but they seem bitter to me. The fruit may also be eaten by wildlife including birds, foxes, opossums, squirrels, and raccoons. Some nurseries charge $.10 per seed, or $20 for a pound (approximately 250 seeds), so I hate to throw them away. I always loose them on the hill behind my house or along the riverbank. I have a small group that I will try to transplant this year growing in my yard. My brother in law has a tree growing in his yard in Frostburg, Maryland that he planted from a seed from a fruit I gave him. I eat the fruit by slitting the fruit widthwise, and scooping out the flesh with a spoon like one would eat a melon.
Many people clear these trees off their river frontage (to give an unobstructed view??), not realizing the value of the tree. They are deciduous, so the leaves will drop by the end of October and will only flesh out a few weeks after the blossoms are gone. Perhaps they didn't care for the foul odor of the leaves when bruised. The trees are rapidly declining in the wild due to development, much to our loss as humans. Substances in the bark have made news recently by being cancer-fighting agents as noted above. In some places there are attempts at cultivating this native tree as a cash crop. The trees also contain a natural type of pesticide, hence have few diseases. The larva of the beautiful zebra swallowtail is immune to it, and lives on the foliage. That's why you only see this butterfly when there are paw paw trees nearby. The paw paw trees can be grown from USDA zones 5 through 8.
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