Hibakujumoku (Japanese: 被爆樹木; also called survivor tree or A-bombed tree in English) is a Japanese term for a tree that survived the atomic bombings of Hiroshima and Nagasaki in 1945. The term is from Japanese: 被爆, romanized: hibaku, lit. 'bombed, A-bombed, nuked'^[1] and Japanese: 樹木, romanized: jumoku, lit. 'trees and shrubs'.^[2]

The heat emitted by the explosion in Hiroshima within the first three seconds at a distance of three kilometres from the hypocenter was about 40 times greater than that from the Sun.^[3] The initial radiation level at the hypocenter was approximately 240 Gy.^[3] According to Hiroshima and Nagasaki: The Physical, Medical, and Social Effects of the Atomic Bombings, plants suffered damage only in the portions exposed above ground, while portions underground were not directly damaged.^[4]

The rate of regeneration differed by species. Active regeneration was shown by broad-leaved trees.^[4] Approximately 170 trees that grew in Hiroshima in 2011 had actually been there prior to the bombing.^[5] The oleander was designated the official flower of Hiroshima for its remarkable vitality.^[4]

Hibakujumoku species are listed in the UNITAR database,^[6] shown below, combined with data from Hiroshima and Nagasaki: The Physical, Medical, and Social Effects of the Atomic Bombings. A more extensive list, including distance from the hypocenter for each tree, is available in Survivors: The A-bombed Trees of Hiroshima.^[7]

Although not as well known as the hibakujumoku in Hiroshima, there are a number of similar survivors in the vicinity of the hypocenter in Nagasaki. Approximately 50 of these trees have been documented in English.^[8]

• Hibakusha, humans that survived the atomic bombs
• List of individual trees