Wednesday, December 10, 2014

Black Nightshade

I've recently written a new post on the topic of toxicity in this plant that you should also read if you've found this page via search or other methods.

1. Solanum nigrum.
Myths of edibility are much shorter-lived than myths of toxicity. If something is poisonous and you keep eating it, you (or your surviving friends and relatives) will soon learn your error. If something is perfectly edible, but you never eat it for fear of poison, then you will never learn what you're missing.

The common weedy plant Solanum nigrum (Black Nightshade) is a premiere example of this. The berries are routinely considered to be poison, even though there are no recorded fatal poisonings unambiguously associated with the plant.

The berries of every S. nigrum plant I've come across have been very edible, tasting like a somewhat floral and mildly sweet tomato. The ripe berries and green leaves are used over much of the world, with the leaves being used as a pot-herb comparable to spinach. Research has suggested that it might not be a good idea to eat the unripe berries, as they sometimes contain a limited amount of solanine.

Plant poisons tend to be polite, in that they have the trait of tasting poisonous. The putative toxin in S. nigrum is solanine, which has a bitter taste. There are reports of some S. nigrum plants having bitter leaves and unpleasant berries, while others have bland leaves and mildly sweet berries. I suppose I should advise you to not eat the unpleasant tasting plants.

The myth of toxicity of S. nigrum seems to have been spread by the European diaspora. European-derived cultures everywhere seem to think it is deadly poison, even while the natives living in the same places continue eating it routinely. Why would Europeans think this plant is poison?

2. Atropa belladonna; UK range map.
In the UK and much of western Europe, there grows another plant with black berries. This one, Atropa belladonna (Deadly Nightshade), is deadly poisonous, with a long recorded history of deaths… but only in Europe where it grows. In Europe, if you taught children that one black berry (S. nigrum) was edible, but another (A. belladonna) was poison, there would be the risk of them making a deadly mistake in identification. In this context, it is perfectly reasonable for European parents to teach their children that black berries are poison.

A. belladonna has spread to a few other places in the world, but isn't something you will generally run into. If you don't know plants well enough to tell the difference between S. nigrum and A. belladonna, then you really shouldn't be eating anything you find outside. The plants are as distinct as a dog is from a cat. You almost assuredly have experience with identifying those animals, so there is absolutely no way you would mistake one for the other. It still is a good idea to teach children not to eat things you can't identify, but you shouldn't be claiming poison is the reason.

3. Diospyros texana.
The aversion to black berries has even carried over to entirely unrelated plants, that just happen to have black, round fruit.

Diospyros texana (Texas Persimmon) is a tree that produces perfectly edible black fruit that many (of European cultural extraction) consider to be poisonous, even though there are no toxic relatives or mimics. It has a long history of utilization as a food source by American natives of the arid Southwest, but has in recent times been marginalized to a landscaping plant because of the peculiar attitudes of the now-dominant culture.
4. S. nigrum.

Forms of S. nigrum have been partly domesticated under the name "Garden Huckleberry". These plants have slightly larger berries and a more upright growth form than most of the wild plants. There are red ("Makoi") and orange ("Otricoli") varieties that people might be more likely to believe are edible.

I've collected numerous seeds from a local (Minnesota) form of S. nigrum, with the goal of using them in a mutation breeding experiment. The basic idea is to expose a batch of seeds to some mutagen, like X-rays or some chemicals, and then grow out the resulting plants to look for variations which might be more useful. Larger or different colored fruit are the most obvious things to look for, but other interesting traits may also appear. I would like to use ultraviolet light as a source of mutations, as UV-light is easy to control and keep contained, but I still need to determine if it will work for these seeds.

There are still occasional reports of people eating S. nigrum and experiencing gastrointestinal distress. They could have had a specific allergic reaction to the new food source. For this reason, people should be conservative about eating plants they don't have experience with.

5. Solanine-rich S. dulcamara.
The putative poison found in S. nigrum is the bitter-tasting solanine. It is not entirely clear if everyone can taste this compound. You can experimentally determine your ability to taste Solanine by tasting the very common S. dulcamara (image #5), which has elongated orange/red berries and purple flowers. S. dulcamara is definitely toxic due to the high levels of solanine found in its leaves and berries. For several years, I have been occasionally tasting the berries (looking for a 'sweet' version), but have found very little variation in the amount of poison. If the fruit of this plant tastes sweet to you, then you should have someone else taste it before you really eat any and you might want to avoid tasting wild things like this as a rule.

If you eat some S. nigrum (or S. dulcamara) berries and get sick, you really can't blame me for it. "Some guy on the internet told me it was ok!" won't hold up in court.

  1. Solanum nigrum
  2. Atropa belladonna
  3. Diospyros texana
  4. Solanum dulcamara