Perilla Mint, Perilla frutescens
Perilla Mint is an escaped ornamental summer annual that grows in shaded areas up to a height of 2 feet. Leaves are simple and opposite, and can have a purple-green tint. All parts of the plant are toxic to livestock, including horses, and cause labored breathing and death. The best time to scout for perilla mint is late April to early June. Most deaths from perilla mint occur in the late summer as other foraging options diminish.