The nightshades – deadly and otherwise

by Sandy Garland

On Tuesday, while working in the woods, our volunteer group came across a number of nightshade plants of two species. The same week, one of our Friday morning volunteers brought in another nightshade species with little white flowers. All this prompted some focused Googling and this is what I found.

From Wikipedia: “Solanum is a large and diverse genus of flowering plants, which includes two food crops of the highest economic importance, the potato and the tomato. It also contains the nightshades and horsenettles, as well as numerous plants cultivated for their ornamental flowers and fruit.”

Solanum dulcamera = Bittersweet, European, or Climbing Nightshade has purple flowers (photo above) and large berries that start green, then ripen to orange and finally bright red. You can often see flowers and all stages of fruit on the same vine. This weed is common in our area and easy to find in the Old Woodlot at the FWG. Because the berries are highly toxic, this plant is sometimes called Deadly Nightshade, but the real deadly nightshade is the unrelated Atropa belladonna.

Solanum ptycanthum = Black Nightshade is likely the one our volunteer brought to the FWG. It has tiny white flowers, similar in structure to the other Solanums (photo at left). Berries are black when ripe and probably edible, but not when they are green. This is the only Solanum listed as native to Ontario in the Canadensys database.

Circaea lutetiana ssp. canadensis = Enchanter’s Nightshade is not in the Solanum genus at all, but instead is related to Evening Primrose. It has very tiny white flowers (photo below) and its seeds are not berries, but little green discs that stick to clothing and hair.

To most of us, the important Solanums are potato, tomato, and eggplant.

Solanum lycopersicum = Tomato fruit, as we know, is edible, even when green. However, the leaves and stems of the plants contain the same toxic alkaloid found in other members of the genus (solanine), although in lower concentrations. See Tomato: Safety

Solanum tuberosum = Potato is the fourth largest food crop in the world. Flowers are white or pale pink, blue, or mauve. The small green fruits, like the leaves and stems, are toxic. Only the tubers are edible. See Potato: toxicity

According to our volunteer, Mirko, potatoes were first brought to Europe as decorative plants rather than a food crop. He sent me this interesting history, published during the International Year of the Potato in 2008: The Potato: Diffusion.

Solanum melongena = Eggplant flowers are white to purple, fruit is large and purple when ripe. Although the fruit is edible, other parts of the plant contain the toxic solanine and can be poisonous if eaten in large quantities. See Eggplant: History

Although this is an extremely superficial view of this genus, it shows how the chemistry of closely related plants can vary considerably. We’ve just had another example of this in the news, when a local woman was severely affected by touching Wild Parsnip, a member of the carrot family. The lesson: at the risk of sounding alarmist, be cautious around any plant unless you know for certain it’s safe. Wear gloves while gardening, and never, never assume a pretty berry is edible.