Gliptostrobussimon metasekvoyya
Metasequoia glyptostroboides, the dawn redwood, is a fast-growing, endangered deciduous conifer. It is the sole living species of the genus Metasequoia, one of three genera in the subfamily Sequoioideae of the family Cupressaceae. It now survives in the wild only in wet lower slopes and montane river and stream valleys in the border region of Hubei and Hunan provinces and Chongqing municipality in south-central China, notably in Lichuan county in Hubei. Although the shortest of the redwoods, it can grow to 167 ft (51 m) in height.
In 1941, the genus Metasequoia was reported by paleobotanist Shigeru Miki as a widely distributed extinct genus based on fossils, before attracting considerable attention a few years later when small populations were found alive in central China. It is a well-known example of a living fossil species. The tree faces considerable risks of extinction in its wild range due to deforestation; however, it has been planted extensively in arboreta worldwide, where it has proved a popular and fast-growing ornamental plant. If the species wasn't discovered when it was, it might have become extinct before being investigated.
Metasequoia glyptostroboides leaves are opposite, 1–3 cm (0.39–1.18 in) long, and bright fresh green, turning a foxy reddish brown in autumn. The pollen cones are 5–6 mm (0.20–0.24 in) long, produced on long spikes in early spring; they are produced only on trees growing in regions with hot summers. The cones are globose to ovoid, 1.5–2.5 cm (0.59–0.98 in) in diameter with 16–28 scales arranged in opposite pairs in four rows, each pair at right angles to the adjacent pair; they mature in about 8–9 months after pollination.
While the bark and foliage are similar to another closely related genus of redwoods, Sequoia, M. glyptostroboides differs from the coast redwood in that it is deciduous, like Taxodium distichum (bald cypress). Similar to T. distichum, older trees may form wide buttresses on the lower trunk. M. glyptostroboides is a fast-growing tree, exceeding 35 m (115 ft) in height and 1 m (3.3 ft) in trunk diameter by the age of 50, in cultivation (with the potential to grow to even greater dimensions). The trunk forms a distinctive "armpit" under each branch. The bark is vertically fissured and tends to exfoliate in ribbon-like strips.
The largest dawn redwood recorded was an isolated specimen in China about 50 meters (160 feet) tall and 2.2 meters (7.2 feet) wide. This tree was killed by a lightning strike in 1951. Several dawn redwoods of this height still live in the eastern part of Metasequoia Valley, where the tree was discovered. The tree's true potential size is much larger, as logs up to 8 meters (26 feet) wide at the base have been discovered in rice paddies.
The thickest and tallest dawn redwoods listed by Monumental Trees are both at Longwood Gardens, outside Kennett Square, Pennsylvania, United States. The widest has a girth at breast height of 5.79 m (19.0 ft), average diameter 1.84 m (6.0 ft), and is 30.18 m (99.0 ft) tall. The tallest is 41.15 m (135.0 ft) tall, and has a girth at breast height of 3.35 m (11.0 ft), average diameter 1.07 m (3.5 ft). Both trees were planted in 1948 and measured in 2018.
Introduced to the Botanical Garden. The seeds of this species were brought from China and sown in the Botanical Garden by academician F.N. Rusanov in 1957. In 1958, in the spring, the introduction of these species was sown in the nursery and studied, and in 1981 they were planted in the East Asian exposition of the Tashkent Botanical Garden. Currently, there are 15 adult trees of this species growing in this exposition.
