The Original Mystery Plant
Dr. John Nelson

Photo by Clint Cook

Way down yonder in the swamp is where these things came from. These are fruits of a native American, an American tree that is. It's a slender tree, deciduous, at home in shaded woods, especially within bottomland forests. For this reason, it is a common component of forests along rivers. The species belongs to a decidely tropical family, but it occurs widely in eastern North America from southern Ontario south to the Florida panhandle and into the Midwest and eastern Texas.

The trees have smooth, gray bark. At the stem tips the handsome terminal buds are naked, not enclosed by protective scales. Look closely, and you'll see embryonic leaves, richly covered with russet hairs. Large, tear-drop shaped leaves tend to be clustered at the ends of the branches.

The crushed, fresh leaves give off a peculiar, stinky odor, but that doesn't bother the zebra swallowtail. This beautiful butterfly lays its eggs on the foliage, and that is the only food source known for its caterpillars. Flowers appear in the spring before the leaves, and they are certainly unmistakeable with a cup-like corolla of six brownish-purple petals and plenty of stamens.

Photo by Gary Ward

The flowers won't win any fragrance awards. Most people describe the scent as rather yeasty or even mousey. This is one of those flowers that has numerous separate pistils, something like a magnolia blossom, and each pistil has the potential of producing a single fruit. Usually, only a very few fruits are produced by a single tree even if it has bloomed heavily.

The fruits are probably the most well-known aspect of this plant. Ripe fruits are prized by a wide variety of wildlife species, and of course, by humans, too. The fruits ripen quickly in the late summer and drop to the ground and are usually consumed eagerly. They are about the size of a stumpy dill pickle or maybe a small banana. The skin is somewhat bitter, and there are a number of large, dark seeds, but the flesh inside is exquisite: a soft, creamy custard full of vitamins and minerals which tastes something like a cross between a banana and a pineapple. One or two of these delicacies cut open will fill a room with a marvelous tropical aroma.

It's a shame the wild fruits are so difficult to market. They bruise very easily and don't travel well. Nevertheless, considerable attention has been devoted to the cultivation of this species, and a number of horticultural varieties have been developed. It is no wonder that this is one of the better- known fruit-producing native plants in North America. Besides that, the trees show some promise as naturally occurring sources of anti-cancer drugs and pesticides obtained from the bark.

Answer to last week's mystery plant

Painted leaf, Euphorbia cyathophora

Dr. John Nelson is the curator of the USC Herbarium.

To learn more about the Herbarium, call him at

777-8196. His department also offers free plant identification.

www.herbarium.org