histogen

See histogen theory;

见histogentheory;

In roots, however, the concept is still applied, and in some angiosperm roots a fourth histogen zone is recognized, the calpytrogen, which gives rise to the root cap.

然而在根中，它还是适用的。在一些被子植物的根中，还发现了第四种组织原，calpytrogen，与根冠发生有关。