Shedding a Dark Light on Suspicious Species

Sunday, May 31, to Sunday, September 6, 2009

Deadly Dinner
Herb Garden

Cassava (Manihot esculenta)

Audio Tour

Toxic tomatoes and culpable cassava?

Amy Stewart and BBG curator Caleb Leech unveil some potentially poisonous and even deadly dinners.

(1:46)

Complete Audio Tour

Toxic plants would never be cultivated, harvested, and sold in the supermarket, right? Wrong! This herb garden includes some everyday crop plants with seriously wicked tendencies. Appearing as mild-mannered produce—or blending in among harmless vegetables in a kitchen garden—these plants warrant watching...

Tomatoes (Lycopersicon esculentum) originated in South America and were brought to Spain in the 1500s, where they were at first thought to be poisonous and grown only as decorative curiosities. Tomato leaves and stems do contain harmful glycoalkaloids, but the delicious fruit (technically a berry) has many excellent nutrients, as well as the powerful antioxidant lycopene.

Consider cassava, a starchy tuber also known as yuca or manioc. Some species of cassava have high concentrations of cyanogenic glucosides, which release deadly cyanide. Nonetheless, in the tropics from South America to Africa to Asia, bitter cassava's poisonous root is eaten by millions of people after it has been first prepared in a way that removes most of the toxins.

The variety most often available in markets in the U.S., sweet cassava, does not contain harmful compounds and requires no special detoxification. It's also processed to make tapioca—the "bubbles" in bubble tea drinks.

Because this woody shrub thrives in poor soils, its slow-growing root is one of the most important sources for carbohydrates in tropical areas of the world. The cooked leaves are also eaten.