The chokecherry (Prunus virginiana) is a common shrub or small tree native to North America. Its edibility is often confusing because the plant presents a paradox: the fleshy fruit is safe to consume, but certain parts contain compounds highly toxic to humans and animals. This conditional safety means consumption depends entirely on proper identification and preparation, specifically avoiding or neutralizing the poisonous components. This article clarifies which parts of the chokecherry pose a danger, the science behind the toxicity, and how the fruit can be safely processed.
Which Parts of the Chokecherry Plant Are Toxic
The danger associated with the chokecherry plant lies in the presence of cyanogenic glycosides, which are distributed unevenly throughout its structure. High concentrations of these compounds are found in the leaves, bark, stems, and the seed pits inside the fruit. The fruit’s pulp and skin, however, are essentially free of these toxins and are safe to eat once fully ripe.
The leaves are particularly toxic, especially when wilted (such as after a frost or if branches are broken), because wilting facilitates the release of the toxic chemical. The seed, or stone, within the fruit is the most common concern for human consumption due to its toxic glycosides. The hazard is only released if the seed pit is crushed, chewed, or damaged, allowing the compounds to mix with enzymes that break them down into poison.
Unbroken, whole pits can pass through the digestive system without causing harm, but crushing them—even unintentionally during processing—releases the danger. The distinction between the safe flesh and the toxic seed pit is a necessary consideration for consumption. The toxic compounds also concentrate in new growth, bark, and stems, which is why livestock poisoning is common when animals browse on the foliage.
The Science Behind the Poison: Cyanide Compounds
The toxicity of the chokecherry plant is due to cyanogenic glycosides, a class of naturally occurring chemicals. The primary glycosides are Amygdalin and Prunasin, molecules that contain a cyanide group. These compounds are not inherently toxic in their intact form, but they become poisonous when hydrolyzed, or broken down.
This breakdown occurs when the plant material is crushed or chewed. This action releases the glycosides, allowing them to mix with specific plant enzymes, such as beta-glucosidase, present in the plant cells. This enzymatic reaction causes the glycosides to rapidly degrade and release hydrogen cyanide (HCN), also known as prussic acid. Hydrogen cyanide is a rapid-acting poison that interferes with cellular respiration, preventing the body’s cells from utilizing oxygen.
Symptoms of mild cyanide poisoning can include headache, dizziness, rapid pulse, rapid breathing, and stomach pains. In severe cases, the inability of the body to use oxygen leads to anoxia, which can quickly result in convulsions, respiratory failure, and death. The amount of HCN released depends on the quantity of crushed material consumed; reaching a dangerous concentration requires rapid and massive ingestion of high-glycoside parts.
Safe Processing and Consumption of Chokecherry Fruit
For human consumption, the key to safely utilizing chokecherries is to physically separate the edible fruit pulp from the toxic seed pits or to neutralize the cyanogenic glycosides. The fleshy part of the fruit is routinely used to make syrups, jams, jellies, and wines because the whole fruit is initially cooked.
Thorough cooking is a crucial step in detoxification, as the heat breaks down the cyanogenic glycosides and allows the resulting volatile hydrogen cyanide gas to dissipate. A common preparation method involves simmering the whole, uncrushed fruit with a small amount of water until tender, a process that typically takes 15 to 20 minutes. Following cooking, the pulp must be strained through a sieve, food mill, or jelly bag to ensure all hard pits and skins are completely removed before the final product.
It is essential not to crush the seeds during initial cooking or subsequent straining process, especially when making juice, as this releases toxins into the pulp. Any small amount of cyanide that may leach out during heating is generally at a level too low to harm humans and can contribute a pleasant, subtle almond-like flavor to the final preserves. The combination of heat and mechanical removal of the pit ensures the preserves are safe, allowing the fruit’s unique tart flavor to be enjoyed.