Many plants in and around gardens and landscaped areas can be poisonous to horses. These include lupines, foxglove, English holly, European holly, daffodils, hyacinths, philodendron, azalea, rhododendron, and yews. Cultural practices and grazing management should be the first approach to protection against poisonous weeds. In part, this is because animal-health problems can result from exposure to excessive quantities of herbicides used to control weeds.
Problems are most likely to result when herbicides or their containers are used improperly.
Although not poisonous, bristles on the panicles stick to skin and have caused abscesses. Stems and leaves are covered with numerous stinging hairs, the sting resembling that of a bee. Plants grow up to six feet in height, with slender, rigid stems branching mostly at the top. Flowers are green to white and arranged on branched spikes arising from leaf axils. The plant is found throughout Ohio, especially along roadsides, fencerows, ditchbanks, shady or moist wood edges.