Diverse Plant Life in Kikuchi Gorge
Kikuchi Gorge is famous for its diverse plant life. The changes in elevation from one end of the 4-kilometer gorge to the other result in a wide range of growing conditions. The lower end of the gorge is 500 meters above sea level, while the elevation at its starting point is 800 meters. Walking uphill through the gorge, you can see how the vegetation changes gradually from tall evergreen trees to deciduous species, and then on to conifer and beech forest in the upper reaches. In total, an estimated 750–800 plant species, of which 250–300 are trees and shrubs, grow in Kikuchi Gorge.
Warm-temperate forest covers the lower parts of the gorge. Common trees in this zone include the Japanese cinnamon (yabunikkei; Cinnamomum yabunikkei), whose dark-green leaves are fragrant and glossy with three distinctive veins; the urajiro-gashi (“white back”) ring-cupped oak (Quercus salicina), so named because its thick, leathery leaves are whitish on the back side; and the isunoki witch hazel (Distylium racemosum), whose tiny red, petalless flowers bloom in dense clusters from March to April. Deciduous trees such as zelkovas and various species of maple are common in the middle part of the gorge, as are Japanese cedars. Near the Momijigase area is a noteworthy grove of giant cedars planted in 1823 by the local daimyo lord, intended for use as construction material.
Up beyond the Hirokawara area, where the gorge’s walking paths end, grow conifers, including firs and the southern Japanese hemlock (tsuga; Tsuga sieboldii), a popular ornamental tree that bears small reddish-brown cones on its outer branches. A deciduous tree known as inushide (Carpinus tschonoskii) also grows here; it is a species of hornbeam with densely double-serrated leaves and a smooth but sinewy trunk sometimes described as “muscular.” Deciduous trees such as beeches and the mizunara oak (Quercus crispula) appear even higher up the mountain, where average temperatures are significantly lower than in the warm-temperate zone.
Two plants readily visible along the walking paths are the thread-like bright-green kiyosumi-ito moss (Barbella flagellifera), which thrives in the wet and humid conditions near the river and hangs down as much as 20 centimeters from tree branches and rocks throughout the gorge, and the iwatabako (“rock tobacco”; Conandron ramondioides), a species with large, tobacco-like leaves that flourishes on damp rocks. Its star-shaped, light purple flowers bloom in summer.