"Todd Milbrandt, a pediatric orthopedic surgeon at the Mayo Clinic in Rochester, Minn, who explains the significance of physes and what makes 20 a special number.
"With a good diet rich in vitamin D and calcium, most girls will grow from age 10 to 14 and be completely done by 16, while boys grow from 12 until about 16 or 18, 'with some, in rare circumstances, growing up until 20,' says Dr Milbrandt * * * After that, their growth plates, also called physes—the cartilage near the ends of each bone—are absorbed into the body, which forestalls further change.
is separated from diaphysis by epiphyseal plate (whose layman term is growth plate) in young adults.
(iii) "Physis is the origin of our word physical, physiology and physics. Physis was the Greek word for the material universe we sense, experience, examine and measure in an attempt to predict future behavior."
Written by Siry of Rollins College in Florida, undated. https://myweb.rollins.edu/jsiry/PHYSIS.HTML