Cyanide is a natural chemical found in many parts of our natural environment. It has a well-earned reputation as a powerful poison, but cyanide is used in many industrial processes as well -- including electroplating, metallurgy, organic chemicals production, photographic developing, manufacture of plastics, fumigation of ships and some mining processes. Due to its wide range of uses, it is important to understand cyanide's effects on plant life should any amount of cyanide be accidentally introduced to an ecosystem.
The immediate effects on plant life of cyanide exposure vary tremendously depending on the species of plant. In some species, high concentrations of cyanide can inhibit respiration and affect a plant's ability to absorb nutrients from soil, in some cases causing plant death. In smaller concentrations, cyanide can diminish new growth and can affect germination of seeds; for some plants, however, cyanide can actually foster seed germination. Indeed, many plant species such as cassava, sorghum, flax, cherries, almonds and beans already naturally contain small amounts of cyanide.
Cyanide is highly mobile in soil, meaning that it has high potential to affect plants and other organisms in soil rather than being bound up by soil particles. At low concentrations, soil micro-organisms convert cyanide into hydrogen cyanide and other compounds that evaporate out of soil. At high concentrations, however, cyanide is toxic to the very micro-organisms responsible for its conversion into evaporative forms, meaning that cyanide not only remains in soil where it can damage plants but also can easily find its way to groundwater.
Plants that have metabolized large amounts of cyanide can be hazardous to animals who eat those plants. Cyanide poisoning of livestock by way of cyanide buildup in grasses and other plants cultivated for cattle grazing have been so problematic that botanists have developed strains of cattle-grazing plants resistant to the buildup of large amounts of cyanide. When a human drinks water or touches soil that has large amounts of cyanide, health problems can quickly ensue. Similarly, humans can be put at risk when eating foods harvested from plants containing large amounts of cyanide.
Even given all of these direct and indirect effects of cyanide exposure to plants, it is highly unlikely for humans to be exposed to large enough amounts of cyanide to be put at risk; still, it's important to know the signs of cyanide exposure just to err on the side of caution. The earliest effects of cyanide exposure are rapid, deep breathing and shortness of breath followed by convulsions (seizures) and loss of consciousness. Prolonged exposure to small amounts of cyanide over long periods of time has been linked to breathing difficulties, chest pain, vomiting, blood changes, headaches and enlargement of the thyroid gland. Exposure to large amounts of cyanide in a short time can cause brain and heart damage and in some cases can lead to coma and death.