Orchids with sympodial growth have a specialized lateral growth pattern in which the terminal bud dies. The growth continues by development of new shoots sprouting from or next to the ones of previous years (such as in the genus Cattleya or Cymbidium).
The base of the stem of sympodial epiphytes, or in some species essentially the entire stem, may be thickened to form what is called a pseudobulb. These contain food reserves for drier periods. At their end appear one or two leaves, or sometimes four or more.
Some sympodial terrestrials, such as Orchis and Ophrys, have two pseudobulbs between the roots. One is used as a food reserve for wintery periods, and provides for the development of the other pseudobulb, from which visible growth develops.
In warm and humid climates, many terrestrial orchids do not need pseudobulbs.