Stems have swellings at certain points called nodes .
A node is the point on a stem where a leaf is or was attached. The area between nodes is termed the internode . Stems usually grow upward to the light, but may be subterranean. In plants which lack leaves, such as cacti, all food is produced in the green stem. Stems may be annual, biennial, or perennial, although some plants with perennial roots have annual stems.