The Katsura tree (Cercidiphyllum japonicum) belongs to the family Cercidiphyllaceae. It is a tall decidous tree that is found throughout Japan, as well as on the Korean Peninsula and in central-southern and eastern China. This tree grows along mountain streams and can reach 20-30 m in height. The barks are grayish brown and shallow-furrowed when mature. The leaves are broad cordate, opposite with smooth toothed edges. The timber is homogeneous, soft and used for building materials and furnitures. The leaves are aromatic and used as a material of incense. It is dioecious. Its Japanese name is said to be a corruption of "香出" (kazu). These yellow-colored deciduous leaves have a sweet aroma. The main component of this sweet smell is maltol, which is also referred to as a caramel-like odor. Incidentally, it is said that the name"Rankoshi" in Hokkaido derives from the Ainu word "ranko-us" (a place where katsura trees grow in clusters). It is called "連香樹" (lian xiang shu) in Chinese.
In Korean, it's called "gye-su-na-mu" (계수나무). In kanji, it is written as "桂樹" (gye-su: 계수). In Korean folktales and nursery rhymes, it often appears as a symbol of the tree said to grow on the moon.
The 21th and 22th in the photo are "Aizen Katsura" of Kitamuki Kannon in Ueda city, Nagano Prefecture.