Question: I would like your opinion on the edibility of chokecherries (Prunus virginiana). Is it true their berries are poisonous?
I’m a bit confused, as several websites mention that chokecherries are an excellent food for birds and some even say they can be used to make jams and syrups. But what really bowled me over was a page on the Canadian Poisonous Plants Information System. It states “Children have been poisoned and have died after ingesting large quantities of berries, which contain the seeds. All types of livestock can be poisoned by ingesting the plant material.”
I was appalled, as when I was young, we used to eat handfuls of chokecherries straight from the tree and we suffered no ill consequences. How is it possible that the berries can be both poisonous and non-poisonous?
Answer: I too used to eat the chokecherries as a boy, in spite of their astringent and none-too-sweet taste.
The secret is that it’s the pit (seed) that is toxic, not the fruit’s rather meager flesh. All cherries and other species of Prunus have poisonous pits. They contain amygdalin, a product the body converts into cyanide, a deadly poison, after consumption. However, people usually don’t eat cherry pits, not even those as small as the ones found in chokecherries. Instead, we spit them out, and thus suffer no risk of poisoning.
Cattle and other livestock eat chokecherries whole and can become poisoned if they swallow too many. Note that the text you found on the web specifies in the text that the children who died had swallowed the seeds.
Chokecherry (Prunus virginiana) is the North American counterpart of Eurasian bird cherry (P. padus). Not only are both very similar in appearance, but they’re widespread on their respective continents and are widely used as ornamental trees, especially purple-leaved varieties, such as P. virginiana ‘Schubert’, P. virginiana ‘Canada Select’ and P. padus ‘Colorata’. Moreover, the indigenous peoples of both continents harvested and consumed the fruits, sometimes even the pits, which can be safely eaten after cooking, as that destroys the amygdalin they contain.
Note that that if a person accidentally swallows a few pits, they won’t be poisoned: a fairly large quantity needs to be eaten, as the dose makes the poison. On the other hand, you shouldn’t make the habit of swallowing them.
Curiously, the pits pass without difficulty through the digestive system of birds and, in the wild, over 70 species feed on them. That also appears to be true for deer, other cervids and bears, all of which eat chokecherries with impunity. On the other hand, sheep, cows, horses, etc. can be poisoned. Other mammals, such as chipmunks and mice, seem to know that the pits are toxic and eat the flesh without swallowing the pits. Note too that even the stems, bark and leaves of Prunus are toxic to many mammals.
If the pits of all Prunus (cherry, plum, peach, etc.) are toxic to humans, how is it possible we can eat almonds, which are extracted from the pits of the almond fruit, another Prunus species (P. dulcis)? There are two answers to that question.
First, after thousands of years of selection, varieties have been developed that contain no amygdalin. They’re called sweet almonds and are the ones you find sold as almonds in grocery stories. But so-called bitter almonds (ones that contain amygdalin) can still be consumed if they are correctly heated beforehand and are, in fact, popular in many European and Asian diets. However, because of the risk to consumers, the sale of bitter almonds is prohibited in many countries.
Note too that the same situation applies to apples (Malus pumila): their seeds or pips are also toxic. That said, some people have the habit of sucking on and swallowing apple pips at least occasionally and yet they get away with it. That’s because, in most cases, apple seeds simply pass through our digestive system intact, so no poison is released. Chewing the seeds or piercing their coat is definitely not wise, as this will release the toxic elements. However, even then, few people are poisoned by apple seeds, as they are much less toxic than most Prunus pits. A healthy medium-sized adult can apparently eat over 200 ground-up pips without suffering serious poisoning.
The truth is many edible plants that have toxic parts or are toxic if they are not cooked beforehand. For more information on this subject, read Edible Plants With Poisonous Habits.
When harvesting plants from the wild or even our own vegetable gardens and orchards, it’s best to stick to consuming parts of plants we know to be safe, and even then, only after giving them the usually recommended preparation!