In his classic book, "Eating in America," Waverly Root tells us, "Americans were slow about taking avocados to their hearts, and in its early prudish days their growers dared not advertise the merit which, privately, they considered likely to prove its strongest selling point."

Then a clever publicity agent hit upon an effective strategy. As Root relates the story, "He had a representative of the avocado raisers' association deny with indignation the false and malicious rumors that the avocado was an aphrodisiac. Sales rose."

Whether avocados really are erotic has yet to be scientifically demonstrated, though the ancient Aztecs certainly thought they were. They even confined their young women indoors during the avocado harvest.

But regardless of the effect of the avocado on the human libido, its own sex life is rather noteworthy. Unique to the botanical kingdom, the avocado flower opens its first day as a female and the next day as a male, making it the Victor/Victoria of the plant world.

The progeny of this sexually conflicted plant is a fruit which, with its buttery flesh, is unlike any other, as the "Oxford Companion to Food" notes. (And organically it is a fruit, a berry to be precise, not a vegetable.)

Though avocados were virtually unknown in Europe until after World War II, they have been cultivated for centuries on this side of the world. According to legend, a Mayan princess ate the first avocado in Mexico around 291 B.C., but archaeologists have unearthed avocado seeds buried with mummies in Peru that date back to 750 B.C. and "The Cambridge World History of Food" maintains that the avocado was cultivated in Central America as far back as 7,000 years ago. Whatever the case, by 1519 when Cortés became the first white man to set foot in what is now Mexico City, the plant was flourishing there. Fernández de Oviedo, the historian of the conquistadors, made note of it in his journal, praising its taste and texture.

The word avocado is derived from the Aztec word "ahuacatl," but around the world the fruit has been referred to by as many as 40 different names, including alligator pear, custard apple, and butter pear.

Though there are more than 500 varieties of avocados grown around the world, there are essentially only three principal strains, which were first catalogued by a Spanish padre named Bernabe Cobo: Mexican, Guatemalan, and West Indian. The Mexican avocado is smooth-skinned, the size of a plum, and purple or black; the Guatemalan avocado is larger with a rough skin which can be green, purple, or black; and the West Indian avocado is smooth-skinned, green, and the largest variety.

Avocados from Florida are of the West Indian variety, while those from California, generally superior in flavor albeit higher in fat and calories, are typically hybrids. For example, the leading cultivar in California, the Hass, named after Rudolf Hass, a mailman who found them growing on a tree in his backyard in La Habra, is a cross between the Mexican and the Guatemalan types. So is the other principal California variety, the Fuerte, which got its name (Spanish for vigorous and strong) when it survived the great freeze of 1913.

Regardless of variety, the avocado is a versatile fruit which can be enjoyed in countless ways. Brazilians put them in ice cream, Nicaraguans stuff them with cheese, Jamaicans turn them into soup, French-speaking Creoles mix them with sugar and lemon and serve them as dessert, Indonesians convert them into a drink, and the Japanese enfold them in sushi rolls. The people of Zaire even brew beer from avocado leaves.

Trendy American chefs put them in salads, use them pureed in place of mayonnaise, flavor cheesecakes with them, make cocktails (such as the avocado martini or "avotini") with them, and even though avocados can turn bitter when heated, grill and batter fry them. On the other hand, some devotees claim that the best way to eat an avocado is to simply season it with salt and pepper and scoop it right out of the shell.

The quintessential avocado preparation, of course, is guacamole, a dish handed down to us by the Aztecs. Though the California Avocado Commission offers recipes for nearly 30 different kinds of guacamole, including Indian, Greek, Italian, Japanese, and Cajun guacamole, the classic version is still probably the best.

When it comes to classic guacamole, Dr. David Starrett, director of Southeast Missouri State University's cutting-edge Center for Scholarship in Teaching and Learning knows a thing or two. And well he should. A biologist by training, he wrote his Ph.D. dissertation on the subject of avocados. His research into the post-harvest physiology of the plant required him to go through nearly 100 avocados with every experiment in his lab at UCLA, and as a byproduct he learned how to put the "olé" in guacamole. He offers the following tips for its preparation.

The key to perfect guacamole is a perfectly ripe avocado, one that is soft when gently squeezed. You can accelerate the ripening of the fruit by placing it in a paper bag with an apple or banana, but once it is ripe it must be used within 24 hours before it gets squishy.

Authentic guacamole is chunky, not smooth; therefore you should never make guacamole in a blender. The implement of choice is a potato masher.

Avoid oversalting guacamole, which is easy to do. If you are going to use the guacamole as a dip for tortilla chips, which tend to be salty, you may not even need to add any salt at all to the guacamole itself.

Be judicious when adding ingredients, such as onions, to guacamole as the delicate taste of avocado is easily overpowered by stronger flavors, which tend to intensify if the guacamole sits before being served.

To keep guacamole from turning brown, place plastic wrap directly on the surface, put the avocado pit back in the mixture, or serve it in a silver container.

Prepare guacamole following these guidelines and people may think you too have an advanced degree in the subject.

Dr. Avocado's Guacamole

More avocados are eaten on Cinco de Mayo, which is just around the corner, than on any other day of the year. This recipe from Dr. David Starrett could easily increase consumption even further. You can use any commercial salsa in the preparation, but bear in mind that some brands have more punch than others.

Ingredients:

8 medium size ripe Haas avocados

3 tablespoons chopped purple onion

3 tablespoons salsa

1 and 1/2 medium ripe tomatoes, chopped

1 clove garlic, finely minced

pinch of salt

Directions:

Halve avocados, remove pits, and peel. Using a potato masher or a large fork, mash coarsely. Gently incorporate remaining ingredients.

Listen to A Harte Appetite Fridays at 8:49 a.m. and Saturdays at 11:59 a.m. on KRCU, 90.9 FM. Write A Harte Appetite, c/o the Southeast Missourian, P.O. Box 699, Cape Girardeau, Mo., 63702-0699 or by e-mail to tharte@semissourian.com.