Flora of Japan

Japan has significant diversity in flora. Of approximately 5,600 total vascular plant species, almost 40% are endemic.^[1] This richness is due to the significant variation in latitude and altitude across the country, a diversity of climatic conditions due to monsoons, and multiple geohistorical incidences of connections with the mainland.^[2]

Japan consists of roughly 4 vegetation zones that are delineated by temperature and precipitation: the alpine region, subalpine region, summer-green broad-leaved forest region and evergreen broad-leaved forest region.^[3][4]

Due to its substantial length of over 3,000 km from north to south and its mountain ranges that can exceed 3,000 meters, Japan's vegetation varies by latitude and by altitude. Evergreen forests tend to appear in the southern half of the Japanese mainland, with broad leaf forests, subalpine, and alpine appearing with increasing frequency to the north and near mountains.^[3][4]

The evergreen forest zone can be found along the coasts of the southern half of Japan and is most common zone in the Ryukyu Islands, Shikoku and, Kyushu as well as parts of southwestern Honshu with equal longitude.^[3] This region rises up to an elevation of 750 meters near Tokyo.^[4] At the coasts, the dominant forest canopy species are Castanopsis cuspidata and Machilus thunbergii. Inland, trees belonging to the genus Quercus are dominant. In lower layers, trees and shrub species include Camellia japonica, Neolitsea sericea, Aucuba japonica, and Eurya japonica. It is a characteristic of this zone that all these are evergreen species.^[4]

These forests can be found in central Japan above 1,000 meters altitude and throughout parts of Hokkaido at elevations between 700 and 1,600 meters. These forests are also called Fagus crenata forests due to the prevalence of this tree species. On the western side, common species include Daphniphyllum macropodum, Cephalotaxus harringtonii, and Aucuba japonica. On the eastern side facing the Pacific Ocean, important species include Ulmus japonica, Arachniodes standishii , and Laportea macrostachya. This region has been particularly affected by human development and clearing of natural forests. Cleared lands tend to be replanted with Larix kaempferi, Cryptomeria japonica , and Chamaecyparis obtusa.^[4]

In Honshu, from 1,600 to 2,500 meters, and Hokkaido at slightly lower altitudes, character species in the subalpine zone are Vaccinium vitis-idaea, Vaccinium ovalifolium, Neottia cordata, Coptis trifolia. Distinguishing trees include Abies mariesii, Larix kaempferi, and Tsuga diversifolia.^[4]

Above 2500 meters, vegetation has to contend with significant snowfall and high winds. Genera that can survive in these conditions include Phyllodoce and Harrimanella.^[4]

• Cercidiphyllum
• Japanese maple
• Azalea
• Chrysanthemum
• Reynoutria japonica
• Japanese beech
• Konara
• Cherry blossom
• Pinus pumila
• Hinoki cypress
• Japanese red pine
• sakaki evergreen
• Japanese red cedar
• Pinus luchuensis
• Cryptotaenia japonica
• Acer ginnala
• Wasabi
• Nandina
• Japanese holly
• Japanese iris
• Juniperus procumbens
• Pittosporum tobira
• Hosta
• Styrax japonicus
• Wisteria floribunda
• Japanese black pine
• Prunus × yedoensis
• Pinus amamiana
• Acer japonicum
• Sciadopitys
• Myoga
• Chamaecyparis pisifera
• Gastrodia amamiana
• Juglans ailantifolia
• Yomogi

The flora of Japan is extensively described in scientific publications such as :

• Makino, T., 1940. Illustrated flora of Japan. Hokuryukan (with renewed editions in 1961 and 1996)^[5]
• Ohwi, J., 1965. Flora of Japan (in English). A combined, much revised, and extended translation. Smithsonian Institution, Washington D.C.^[6]
• Iwatsuki, K. (岩槻, 邦男), Boufford, D.E. & Ohba, H. (大場, 秀章), 1993–2020. Flora of Japan. Kodansha^[7]
  • vol. 1 : Pteridophyta and Gymnospermae (1995)
  • vol. 2a-c : Angiospermae, Dicotyledoneae, Archichlamydeae (1999–2006)
  • vol. 3a-b : Angiospermae, Dicotyledoneae, Sympetalae (1993–1995)
  • vol. 4a-b : Angiospermae, Monocotyledoneae (a 2020, b 2016)
  • General index (2020)

More over, here are some publications of interest about the Japanese flora : Tomitarô Makino, who was lecturer of botany at the imperial university of Tokyo, published a large amount of contributions from 1901 to 1914 collectively called "Observations on the flora of Japan" (and before that some other under various names among which "Plantæ Japonenses novæ vel minus cognitæ")

• Makino, T., 1901–1905. Observations on the Flora of Japan (Fascicula 1–5)^[8]
• Makino, T., 1896–1914. Observations on the Flora of Japan. published within the botanical journal (in Japanese : 植物学雑誌, romanized : "Shokubutsugaku Zasshi") edited by the Botanical Society of Japan^[9]

• List of ecoregions in Japan
• Wildlife of Japan