ツツジ科ツツジ属の半常緑低木で、学名は Rhododendron kaempferi var. kaempferi (syn. Rhododendron obtusum var. kaempferi)。英名はありません。
"Yama-tsutsuji" (Rhododendron kaempferi var. kaempferi) belongs to Ericaceae (the Azalea family). It is a small semi-evergreen tree that is distributed southward from southern Hokkaido to Honshu, Shikoku and Kyushu in Japan. This tree grows in foothills to montane forests or forest edges, and can reach 1-3 m in height. The young branches are reddish-brown and white hirsute. The leaves are elliptic to ovate-elliptic and alternate. The 2-3 vermilion flowers bloom on the terminal branches from April to June. The corolla is funnel-shaped and divided into 5 clefts with 5 stamens. The 61th to 63th photos are called "Elizabeth". (Not sure if 'Elizabeth Gable' or not)