From deadly nightshade to the tasty tomato, the Solanaceae includes some of the most intriguing plants on the planet. Though now found throughout the world in gardens, crop fields, and growing wild along roadsides, most of the nearly 3,000 species are native to tropical regions near the equator, primarily in South America.
The name nightshade derives from the general name for plants in the genus Solanum, which includes various weeds as well as several common vegetables. Presumably this quaint, ancient common name stems from an association between night as a time of evil and the poisonous qualities of members of the genus as well as the entire family (even edible species, such as the tomato, contain poisons like solanine in their leaves and stems, and the green spots on potatoes).
Over the centuries the relationship between mankind and this family, also sometimes referred to as the Potato Family, reads like a soap opera or a Gothic novel, full of love, hate, fear, mystery, and passion. Solanaceous kin have played pivotal roles in dramas ranging from the Irish Potato Famine to the tobacco controversy to the debate over whether ketchup qualifies as a vegetable on school menus. While some of the plants are under indictment as the culprits of serious (even deadly) illnesses, others are looked to as harbingers of health. And some are just, well, really beautiful flowers - no mystery there!
The family member that perhaps most exemplifies this dichotomy of good versus evil is the tomato (Solanum lycopersicum), once called "wolf peach" and shunned as poisonous, now a worldwide favorite food and flavoring. In a true rags-too-riches tale, the tomato went from the wilds of the Peruvian Andes to Aztec gardens in Mexico, then rode aboard Spanish galleons to the Caribbean and Europe.
In Spain it took the romantic name pomi d'oro ("golden apple" - the original versions were probably small and yellow) and in France pommes d'amour ("love apple" - for supposed aphrodisiac properties). But in the beginning, Europeans mostly grew the tomato as an ornamental curiosity. Eventually it was the Italians who most fully embraced its culinary possibilities, as any peek inside an Italian cookbook shows.
After a 200-year European tour, the tomato came back across the Atlantic to America in the 1700s, but physicians often warned against eating it, claiming a link to various illnesses, including cancer. Despite this, many were willing to take the risk, seduced by the tomato's edible delights, and by the mid 1800s farm journals were pointing to the tomato as the latest gardening craze.
Soon after that, the tomato also became the "rainmaker" ingredient for the success of mega-companies like Campbell's Soup and Heinz. Now, ironically, the tomato's high level of the pigment lycopene is touted as a cancer preventer. So the love apple has come full circle - from table to toxic to table again. Thankfully many of the varieties developed during the tomato's colorful past, like 'Mortgage Lifter', 'Mr. Stripey', and 'Arkansas Traveler', are back in vogue as heirlooms.
And what's the answer the age-old question, "Is the tomato a fruit or a vegetable?" Though technically the structure of the tomato qualifies it as a fruit, in 1893 the U.S. Supreme Court ruled that it's a vegetable. The reason: It's eaten during the meal and not as a dessert!
Other solanaceous species bear out the yin and yang qualities of the family. Jimson weed is a powerful, potentially lethal, hallucinogenic plant. Mandrake (Mandragora officinarum) has long been associated with witchcraft. And belladonna or deadly nightshade (Atropa belladonna), considered one of the most toxic plants in the Western hemisphere, can be helpful or harmful, depending on how it's used. A drop in the eyes dilates the pupils, centuries ago considered an alluring look for women in Egypt, Italy, and Babylonia; while the Romans found it a highly affective poison, thought to be the cause of several infamous murders.
On the flip side, the Solanaceae also includes the popular ornamental plants petunia, angel's trumpet, Nicotiana, and Calibrachoa. A few less-familiar lovelies that warrant wider use in the flower border are Schizanthus, Salpiglossis, and Browallia. And of course those stalwarts of the vegetable garden: eggplants, potatoes, and peppers (also tomatillo, the key ingredient in Mexican salsa verde).
Coincidentally, what puts the deadly in deadly nightshade also puts the hot in hot peppers - chemical compounds known as alkaloids. In peppers, the kick is actually a collection of alkaloids called capsaicin. Bell peppers have none. But peppers like jalapeno, Scotch bonnet, and Tabasco have varying degrees of hotness that some people find downright addictive. Rated for "heat" in Scoville units, the record-holding hot pepper as of February 2011 is Capsicum chinense 'Naga Jolokia', with a rating of over a million units (jalapenos have 2,500-5,000 units). Now that's not a pepper for the faint of heart!