Plants may be classified according to their use. You could also use this category to identify plants as edible vs. poisonous. Woody plants have woody stems and generally live for several seasons. Biennials produce vegetative growth in the first year. In the second season they form flowers, fruits and seeds before dying.
Perennials survive three or more seasons.
There are both woody and herbaceous perennials. Usually temperatures below 50 degrees will cause some type of damage. Subtropical plants can tolerate some freezing temperatures but cannot survive in areas with a cold winter climate. The outdoor plants in this area are all temperate zone plants. Vegetables and flowers that grow in temperate zone gardens can also be classified as cool season or warm season crops.