Oaks and Acorns of Aso
The acorn, or oak nut, is the fruit of oaks and their close relatives (genera Quercus and Lithocarpus, in the family Fagaceae). They usually form singly or in pairs, and are enclosed in a tough, leathery shell carried in a cup-shaped cupule.
The shape of the acorn will depend to some extent on the particular species of tree. The shape and appearance of the shell that surrounds the acorn also vary considerably, again depending on the type of tree. In Aso there are a number of different acorn-producing trees, each bearing their own unique acorn.
The Japanese oak (Quercus mongolica ssp. crispula), Konara oak (Quercus serrata), Shirakashi (Quercus myrsinaefolia), Ichiigashi (Quercus gilva), and Japanese evergreen oak (Quercus acuta), are all examples of trees that produce acorns with relatively small cupules that cover only a small portion of the acorn itself.
Japanese chestnut oak (Quercus acutissima) and Daimyo oak (Quercus dentata) trees, on the other hand, produce acorns with large, prominent cupules that cover most of the nut.