An easy way to recognize a poisonous plant is by snapping a stem to see the colour of the sap, (don’t get the sap on your skin) generally if the sap is white, it is poisonous although poisonous plants can also have a clear sap.
Many plants are poisonous to horses. Toxins are present in varying amounts under certain conditions such as when plants are stressed or wet. Though poisoning can be rare its good to be aware of a plants potential to poison a horse when selecting plants that horses may have access to. These plants have been know to cause symptoms such as rapid breating, convulsions, low blood pressure, calcium deficiency, colic, sweating, liver failure and even death.
We have listed some of the plants that have the potential to poison horses which are worth investigating further if you own horses.
Red Maple (acer rubrum)
Prunus (cherries, plums, peaches)
Blue canary grass
Hairy darling pea
Dwarf darling pea
Mother of millions
Purple rubber vine
St Barnabys thistle
Some plants cells contain idioblasts which contain sharp needle like crystals of calcium oxalate. These are inside a gelatinous material which swells and shoots out the crystals when chewed. Some of these plants have an inflammatory effect as well so the inside off the mounth and throat becomes swollen causing obvious problems to both horses and people.
Some of the plants that cause this are