Caudex

A caudex (pl.: caudices) of a plant is a stem,^[1] but the term is also used to mean a rootstock^[2] and particularly a basal stem structure from which new growth arises.^[3]

The caudex of a tree fern resembles the trunk of a woody plant, but has a different structure.

The caudex of Jatropha cathartica is pachycaul, with thickening that provides water storage.

Certain cacti can develop a caudex too; here Acanthocereus maculatus

In the strict sense of the term, meaning a stem, "caudex" is most often used with plants that have a different stem morphology from the typical angiosperm dicotyledon stem;^[1] examples of this include palms, ferns, and cycads. The largest of all caudices is that of the ombu (Phytolacca dioica) of the Pampas of South America, which can be 15 m (49 ft) thick.^[4]

The related term caudiciform, literally meaning stem-like, is sometimes used to mean pachycaul, thick-stemmed.^[3] Caudices should not be confused with lignotubers which can also be very large.

Etymology

The term is from the Latin caudex, a noun meaning "tree trunk".^[2][5]