The summit of Mount Tsukuba in southern Ibaraki Prefecture has two peaks, one regarded as female and the other as male. Rising to 876 meters, with a shrine on the top dedicated to Izanami no Mikoto, the female creator deity, Nyotaisan is just 6 meters higher than Nantaisan, topped by a shrine to the male creator deity, Izanagi no Mikoto. Tsukuba Shrine is located at the foot of the mountain, which is mentioned in the eighth-century Man'yoshu collection of poems, and close by is Omido Buddhist Temple.
The formation of Mount Tsukuba, which is now part of the Suigo Tsukuba Quasi-National Park, began around 300 million years ago, when molten granite erupted through the Earth's crust deep under the ocean. Subsequently subjected to enormous tectonic pressure, this igneous extrusion was gradually pushed upward to create both the twin peaks and the hilly land that extends to the north and east, with the Kanto plain to the west. However, until the Jomon Period, from 10,000 to 3,000 B.C., the Kasumigaura inlet close to the town of Tsuchiura still extended all the way round to the western base of Mount Tsukuba. Seashells discarded by settlers at that time can be found on the lower western slopes.
As fascinating as all this is, though, what makes Mount Tsukuba so interesting is that it now hosts plant communities from both the cool-temperate and warm-temperate regions. For instance, cool-temperate trees such as buna (Fagus crenata; Japanese beech) can be seen growing near the summit of the male peak, while warm-temperate, evergreen aka-gashi (Quercus acuta; Japanese red oak) can be seen on lower slopes and also near the summit on its southern side. This latter tree gets its common name from the reddish color of its timber.
Close to the male summit there is a splendid, 1.5-km woodland trail along which many of the larger plants are labeled with both their botanical and Japanese names. The trail's three viewpoints offer different perspectives of the landscape below. When the weather is fine, it is possible to see Mount Fuji in the distance.
The overall shape of deciduous trees is best observed in winter. Take, for example, the mizunara oak (Q. mongolica var. grosseserrata), whose rough, light-brown bark has vertical fissures and whose leaves have large teeth along the margin. The upper half of the leaf is wide and the leafstalk, or petiole, is very short, because mizunara oaks are adapted for growth in windy areas; on Mount Tsukuba they grow alongside hardy Japanese beeches.
Beech trees are loved by all and are the kings of the deciduous forests. They can grow up to 30 meters high, with trunks 1 meter in diameter. There are only two prefectures in Japan where beech trees do not grow naturally -- Chiba and Okinawa -- and Mount Tsukuba has the best stand of them close to Tokyo.
Beech trees have a great capacity to absorb water, and the country's largest specimens are found in mountainous areas along the Sea of Japan, where annual snowfall is high. In winter, these trees' bark is easy to identify as it is smooth and light metallic-gray in color.
Winter buds on beech trees are brown and slender, from 1 to 3 cm long and pointed at the tip, while oak buds are fat and rounded. Beech trees are also monoecious, meaning that male and female flowers occur as single-sexed flowers on the same plant, opening in May just as the new leaves emerge.
Closely associated with Mount Tsukuba's beech and mizunara oak woods is the bamboolike sasa that covers large areas of the woodland floor. Along the Pacific Ocean side of Japan, including the Mount Tsukuba area, suzu-dake growing to between 1 and 2 meters are common. Botanically known as Sasamorpha borealis, these are less rampant than sasa.
Meanwhile, on some beech trees, especially on the north side of Mount Tsukuba, you can see the climbing evergreen tsuru-masaki (Euonymus fortunei; spindle bush). Like ivy, this climbs with the aid of adventitious roots -- i.e., ones that grow from stems. The leaves are small, being only 2-6 cm long, and are oblong with tiny serrations along the margin.
As well, Tsuru-ajisai (Hydrangea anomala ssp. petiolaris; climbing hydrangea) can be seen growing on large rocks in the area. Its flowers, which open during the rainy season of June and July, are large, flat-headed panicles 10-18 cm in diameter.
Yet another deciduous climber encountered on the mountain is tsuru-ume- modoki (Celastrus orbiculatus). During the winter months the bright orange-red fruits, each 7-8 mm in diameter, hang in bunches from the branches and are a favorite food of the musasabi (Petaurista leucogenys; giant flying squirrels) and Honshu-momonga (Pteromys momonga) living in Mount Tsukuba's woods.
Togoku-mitsubatsutsuji (Rhododendron wadanum) is a deciduous rhododendron that also grows in Mount Tsukuba's arboreal wonderland, and the first word in its compound Japanese name alludes to the Kanto area where the species grows. Its mauve-colored flowers open between April and June as the leaves emerge. At the same time, too, nirinso (Anemone flaccida; Japanese woodland anemone) comes into bloom, its white-to-light-pink flowers borne in pairs just below the whorls of three-lobed leaves. Also around the same time you may be lucky enough to see the small, pinkish-white flowers of the Eizan-sumire (Viola eizanensis; Eizan violet), which is also distinguished by its leaves with three deeply divided lobes, somewhat like a cut-leafed maple.
Botanists have identified more than 65 species of ferns in Mount Tsukuba's forests, and many plants were first discovered there. As a result, many plants' names include that of the mountain, such as Tsukuba-kinmonso (Ajuga yesoensis var. tsukubana), a native bugle that only grows on the Pacific Ocean side of Japan, and Tsukuba-torikabuto (Aconitum japonicum ssp. maritimum; Tsukuba- aconitum).
Enjoy Mount Tsukuba; take nothing but pictures and leave nothing but footprints.
