Sakju County in North Phyongan Province of the DPRK has a plant reserve established to protect the community of Japanese cucumber tree, a temperate-zone plant.
The county is densely wooded with not only the cucumber tree community but also such tall trees as oak, black walnut, linden and pine, and shrubs and vines.
At present, the community covers an area of about two hectares.
The trees of the community are 22 to 25 m tall on average, 81 to 82 cm round at root neck and 20 to 25 cm across at chest height. A flower comes into bloom in mid-May and a fruit ripens early in October. A tree produces about 10 kg of seeds.
The community is protected as it is of great academic significance in studying the biological features of cucumber tree and it adds more beauty to the scenery.