// Twitter Cards // Prexisting Head The Biologist Is In: Black Nightshade 2

Sunday, January 8, 2017

Black Nightshade 2

The potential toxicity of Solanum nigrum fruit has been much debated. I had previously written about this species and some thoughts about why people might think it was poisonous. I generally consider it's ripe fruit to be edible and I routinely eat small numbers of them with no negative effects. However, there are still reliable reports of toxic reactions to the fruit (Joseph Lofthouse's reporting) that should be cause for concern to those unfamiliar with the plant.

I think the species had great potential as a future domesticated plant for the vegetable garden. The plants don't seem to have any real disease issues, especially when compared to the related tomatoes. Improvements in fruit size, sweetness, or total production would be worthwhile traits to develop. To that end, I've been on the lookout for wild plants with improved traits to help start a breeding program.

Last summer (2016) I grew several plants from saved seed. In our fenced in garden area, several additional wild weedy plants grew. I was pleased to find one of the wild plants had large berries, on average maybe twice the volume of the berries I'd planted. Rabbits were getting into the garden, so I kept a close watch on the plant while waiting for the fruit to mature.

Top: Extra-large and extra-toxic.
Bottom: Typical and edible.
Once most of the berries had ripened, I collected a sample from the different plants. I took the berries inside to photograph and save seeds. The smaller berries tasted just as I had expected. The larger berries...  I immediately spit them out. The larger fruit had a significantly higher level of solanine than I had ever experienced in this species. I knew exactly what this agent tasted like from tasting the closely related S. dulcamara, which is consistently toxic to humans.

This plant exemplifies some of issues leading to the ongoing debate about this species. I'll eat berries from most plants of this species, but there is no way I would ever eat a handful of berries (or even a single berry) from this plant. I know how to recognize the plant's poison, but you may not.

It took me several years of sampling fruit from every plant I found of this species before I found one that was poisonous. You might find a poisonous one on your first try. Your risk of tasting a couple berries will be minimal, but you should always take great care when eating a plant that you're not very familiar with.

Even though the larger berries were toxic, I'm still going to plant the seeds I collected from them. I'm hoping some of the plants in the next generation will have the larger fruit and yet not be toxic. Even if the two traits are closely linked, eventually I should be able to find a plant that separates them. Wish me luck.