Oleander is an evergreen shrub that seems to grow everywhere in California—in yards, parks, and along freeways. It is often grown as a hedge that can reach up to 20 feet tall. The leaves are thick, leathery and dark green. White, pink, or yellow flowers that are sweetly scented grow in clusters at the end of each branch.
Oleander is also one of the most poisonous plants and contains numerous toxic compounds, many of which can be deadly to people and animals. It is especially dangerous to horses; signs of a poisoned horse include severe diarrhea, colic, and abnormal heartbeat.