If it's exotic and breathes carbon dioxide, chances are John Rashford knows all about it.

For decades, this ethnobotanist has studied many of the world's most unusual plants and how humans use them.

Forget apples and oranges, Rashford is more interested in breadfruit and ackee.

That's breadfruit, as in the starchy, tropical fruit sought by Captain William Bligh on his famous voyage aboard the HMS Bounty, in which his crew mutinied after leaving Tahiti. And ackee, the national fruit of Jamaica, which can prove fatal if it's consumed before it ripens.

Rashford, an anthropology professor, finds easy examples of the importance of plants in the history of man.

He might remind his audience that the story of Adam and Eve begins in a garden, with Eve reaching to a tree for forbidden fruit. Or he might discuss the more practical aspects of plants, and man's use of flora for medicine, building and clothing.

"I don't think it's possible to come up with a theory of human life without looking at plants," he says.

Rashford finds himself traveling often, especially to Hawaii, where he attends board meetings for the National Tropical Botanical Garden. He visits Tanzania to study the Hadza people – hunter-gatherers who use the large and oddly-shaped baobab tree for food, shelter and religious purposes.

When Rashford is home in Charleston, he can be found in his College office, surrounded by books, journals from the Society of Economic Botany and unusual potted plants, many of which are gifts from students.

But despite his devotion to plants, Rashford admits he's not much of a gardener.

"I think I travel too much," he says. "Nature is my garden."