Plant defense against herbivory
![Foxgloves produce several deadly chemicals, namely cardiac and steroidal glycosides. Ingestion can cause nausea, vomiting, hallucinations, convulsions, or death.](/Images/godic/202501/12/Foxglove25858.jpg")
![Timeline of plant evolution and the beginnings of different modes of insect herbivory](/Images/godic/202501/12/InsectPlantEvol.svg5859.png")
![Viburnum lesquereuxii leaf with insect damage; Dakota Sandstone (Cretaceous) of Ellsworth County, Kansas. Scale bar is 10 mm.](/Images/godic/202501/12/ViburnumFossil5859.jpg")
![A Plain Tiger Danaus chrysippus caterpillar making a moat to block defensive chemicals of Calotropis before feeding](/Images/godic/202501/12/Plain_tiger_moat5859.JPG")
Plant defense against herbivory or host-plant resistance (HPR) describes a range of adaptations evolved by plants which improve their survival and reproduction by reducing the impact of herbivores. Plants can sense being touched, and they can use several strategies to defend against damage caused by herbivores. Many plants produce secondary metabolites, known as allelochemicals, that influence the behavior, growth, or survival of herbivores. These chemical defenses can act as repellents or toxins to herbivores, or reduce plant digestibility.