When I kissed a cop down on 34th and Vine, he broke my little bottle of . . . Saffron? Ginger? Even potato juice could have been the secret elixir in Love Potion No. 9.

An expert says nutrients that cured scurvy gave New World dwellers a high they confused with love. And the lore lives on as Valentine's Day approaches."Some of the `spring tonics' and early herbs promoted a euphoria that increased the ability to do everything, including sex," says Jeannie Fernsworth, an instructor at the New York Botanical Garden.

Explorers who came to the New World centuries ago were often suffering from malnutrition, Fernsworth said. When they started eating avocados, limes, oranges and other healthy foods, they may have mistaken the subsequent energy boost for lust.

Consequently, even the most unlikely plants became known as aphrodisiacs. While researching an article on New World plants, Fernsworth ran across an observation from the 1500s that credited potatoes with promoting lust.

But love potions long existed outside the New World.

In "A Midsummer-Night's Dream," Shakespeare mentions a white and purple flower whose juice, placed on "sleeping eyelids," will make a "man or woman madly dote upon the next live creature that it sees."

Lothian Lynas, head reference librarian at the Botanical Garden, says Shakespeare was referring to a wild pansy known in this country as the Johnny-jump-up.

In Woody Allen's new movie "Alice," a venerable Chinatown herbalist offers a New York City matron an unidentified potion with similar properties.

Allen's spokeswoman, Lisa Hintelmann, said that particular potion was purely imaginary.

"I wish it existed," she said.

Mary Forsell, author of "Heirloom Herbs" (Villard Books, $29.95.), speculated on what it might have been were it real.

"Chinese herbs are not only composed of plants but often contain mysterious powdered ingredients they don't like to divulge," she said. "It could have been a musk ox for all we know."

Many herbs also freshen breath, not a bad thing for romance either, Forsell said.

The author has also discovered a number of plant rituals that believers swear will make a person more irresistible. Among them:

- Hide a rose, "the herb of Venus," in your pocket and think about your beloved.

- Mix black tea with rosemary, thyme, mint, rose petals and lemon leaves. Drink it under a waxing moon.

- Ginseng, an Oriental tonic, simultaneously sedative and stimulating, supposedly offers improved concentration and endurance.

Forsell isn't sure whether these methods actually work. Her friends eagerly volunteered to test them this Valentine's Day.