Orchids are a large tribe of flowering plants that are mostly found in humid tropical regions. Most orchids live as epiphytes, using other plants to support themselves, though some temperate varieties live in soil and form tubers to survive winter. Orchids have thick, succulent organs that allow them to withstand low water availability, and epiphytic orchids can survive on dew and damp air alone. Orchids can be divided into categories based on their growth type and place of growth.