Neoteny

the ability of certain organisms to attain sexual maturity and reproduce during the larval stage or elsewhere in their early ontogeny.

Neoteny is known to occur in some amphibians, arthropods, and worms, and in many plants. The larvae of the caudate salamanders of the genus Ambystoma, or axolotls, are the classic example of neoteny. Axolotls lost the capacity for metamorphosis but are able to reproduce, retaining the form of an aquatic animal with gills, fins, and other larval organs. Neoteny gave rise to the perennibranch caudate amphibians, such as the cave proteus (Necturus maculosus), the blind newt (Typhlomolge rathbun), and sirenians. These are matured “larvae” that maintain an aquatic mode of life.

In the plant world, neoteny is found among bryophytes, club mosses, ferns, gymnosperms, and angiosperms. For example, the simple organization of structures in the duckweed originated as a result of a cessation in development during one of the earliest stages of ontogeny. An interesting example of neoteny is the female gametophyte in angiosperms, the embryo sac.