Vegetation of Ooiwago , Yamaguti Prefecture

Ooiwago (literally Villagz covered with large ro”ks) locates in Magura- Mura atii Kibe-Mura in Yamaguti Prefecture, and is preserved legally as National Natural Monu- ment from the view-point of geology. It is a kind of the so-called ”Steinmeer” covered with large rocks 1 ― 7 m. in diameter. The rocks are quartz-diorites and very hard and solid, and older than granite in geologic age. The rain water passes the rock cover through into ground, and accordingly the rock desert is very dried, resulting the poor growth of plants on the rocks. The lithophytes and exochomflphytes are often seen on the rocks, and the chasmochomophytas are also observed in the cave formed between rocks as such a space is sectionally somewhat humid. The marginal part of the rock desert is always menaced with the invasion of trees and herbs from the surrounding forest. The first invaders are generally climbing plants,, forming a beneficial environment for svxcessors immediately following.