ENDOGENOUS a.
Increasing by internal growth and elongation at the summit, instead of externally, and having no distinction of pith, wood, and bark, as the rattan, the palm, the cornstalk.
EXOSKELETON n.
The hardened parts of the external integument of an animal, including hair, feathers, nails, horns, scales, etc.,as well as the armor of armadillos and many reptiles, and the shells or hardened integument of numerous invertebrates; external skeleton; dermoskeleton.