pericycle
noun
peri·cy·cle ˈper-ə-ˌsī-kəl 
: a thin layer of parenchymatous or sclerenchymatous cells that surrounds the stele in most vascular plants
pericyclic
ˌper-ə-ˈsī-klik -ˈsi-
adjective -ˈsi- 
Word History
Etymology
French péricycle, from Greek perikyklos spherical, from peri- + kyklos circle — more at wheel
First Known Use
1890, in the meaning defined above