evergreen oak, (kokuji)
樫 centers on a specific type of oak tree: the evergreen oak. It is a kokuji created in Japan to name this tree.
樫 is a kokuji, a character created in Japan. It combines 木 (tree) with 堅 (hard, firm) to represent the hard wood of the evergreen oak.
The tree radical 木 beside 堅 (hard) points to a tree with hard wood: the evergreen oak.
For かし, imagine a sturdy oak tree that you can 'cash' in for its valuable hard wood: cash -> かし.
—
evergreen oak
Quercus gilva (species of oak)
cork oak
ubame oak (Quercus phillyraeoides)
ubame oak (Quercus phillyraeoides)
oak flour (esp. as animal food); acorn flour
large evergreen oak
quercus myrsinifolia; bamboo Leaved Oak; quercus myrsinaefolia
ring-cupped oak (Quercus glauca); Japanese blue oak
Quercus sessilifolia (species of oak)
Japanese evergreen oak (Quercus acuta)
black oak