 Young foliage and immature female cone from an ornamental specimen [C.J. Earle].
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Metasequoia glyptostroboides Hu & Cheng 1948
Common NamesDawn redwood, water fir, water larch (3), SHUI SHAN [Chinese] (literally, water China-fir) (4).Taxonomic notesThe sole species in Metasequoia S. Miki 1941, a genus initially described from fossil material (see Remarks).Description"A tree up to [45 m] high, with a tapering trunk broadening to the buttressed base; conical when young, developing a broad, rounded crown with age. Bark reddish-brown when young, becoming darker, greyish, fissured, exfoliating in long, narrow strips. Branches ascending. Branchlets glabrous, of two kinds, persistent and deciduous. The persistent bright, reddish-brown when young, shallowly ridged, carrying the deciduous branchlets, numerous vegetative buds and a few leaves. The green deciduous branchlets are up to about [7.5 cm] long, often longer on young trees, usually arranged distichously, more or less horizontal, ribbed with the long decurrent bases of up to 50-60 or more leaves. Buds non-resinous, opposite, or sometimes sub-opposite, usually in pairs at the base of deciduous branchlets but sometimes solitary between the branchlets. They are ovoid or ellipsoid, [2.5-5 mm] long, [1.3-3 mm] wide; scales light reddish- or yellowish-brown, ovate, with a linear keel. They are borne on very short stalks, more or less concealed by the smaller basal scales. Leaves linear, flattened, straight or slightly curved, pectinately arranged, obtusely pointed or shortly mucronate, tapering abruptly towards the articulated junction of the lamina with the decurrent base. They are about [12 mm] long and [1.6 mm] broad on mature trees, but on seedlings and young trees are generally [24-32 mm] and sometimes up to [64 mm] long. The upper surface is bright green, with a narrowly grooved midvein, the under surface bearing obscure lines of stomata, lighter green or slightly glaucous, the midrib slightly raised. In autumn, the leaves turn reddish-brown before they are shed with the deciduous branchlets. A transverse section of a leaf shows a median resin-canal under the single vascular bundle, and two marginal resin canals. Male strobili ovoid, up to [5 mm] long, numerous, decussately arranged on long spikes or panicles. Female strobili sub-globose or short cylindrical, up to [20-25 mm] long, terminal, solitary and pendulous on sparsely leaved lateral branchlets. Scales woody 20-30, in decussate pairs, the upper 3 pairs and the lower 2-3 pairs sterile, the fertile scales each bearing 2-9 usually 5-8 ovules, the outer surface of the scale transversely elliptic or broadly triangular, with a horizontal groove. Seed light brown, usually obovate, [5 mm] long, with 2 broad, thin, paler wings. Cotyledons usually 2. ... For a study of the wood anatomy, see Li, in Tropical Woods. (1948) 94, 28 - 9" (3).RangeChina: Primary occurrence near the Sichuan-Hubei border, ca. 30°10'N, 108°45'E, with an outlying occurrence in NW Hunan; at 750-1500 m elevation (1, 8).E Sichuan, SW Hubei, NW Hunan, at 750-1500 m elevation (1). Typically found on shady, moist sites such as ravines stream banks. The species was discovered in by a Chinese forester, Gan Duo, when a small population was found in Modaoqi on the Sichuan-Hubei border. From which one to three Modaoqi trees were later sampled to produce the entire seed source for trees grown outside China before 1991. A more detailed exploration in 1947 found the species to range over an area of about 800 km2. The center of population, supporting a population of about 6,000 large trees, was in the nearby Shuishaba valley in Hubei. Much of this population was logged following the Revolution in 1949. In 1986, an outlying population was found in Hunan (7). The species is, of course, rare and sensitive to human impacts. It is [as of 1980] protected from cutting, but not from habitat degradation, and very few seedlings were observed in 1980 (9).Big TreeThe type specimen, in Modaoqi, was in 1980 measured at 241 cm in the buttressed portion of the trunk, and 167 cm above the buttress. I believe this is the specimen pictured here. Several trees about 50 m tall are found in the Shuishaba valley. An isolated tree formerly grew a few kilometers to the north at Wangjiaying, 220 cm diameter and 50 m tall; this was the largest tree yet recorded, but was killed by a lightning strike in 1951 (9). A visit to the Hubei population in 1980 found stumps over 2 m diameter, logged between 1950 and 1980 (7). There is a specimen 36.9 m tall with a dbh of 135 cm at the College of William and Mary, Williamsburg, Virginia (2).OldestThe oldest confirmed ages are 50 years, for trees planted in the US in 1948. The size of subfossil remnants in China (above) suggests ages of at least 100 years, and ages of 300 and 450 years have been mentioned based on extra[polations from partial cores (9). In the absence of further data, though, such ages must be regarded as fanciful.DendrochronologyEthnobotanyAt the time of its discovery, it was commonly planted as an ornamental by the local people (3), and has since become a very popular tree, with several million trees (mostly rooted cuttings) planted in China each year. It is also a popular ornamental in the West. Nearly all trees now growing outside China are from seed stock derived from one to three Chinese trees during 1947 collections. In 1983 it was noted that this Western stock suffers from inbreeding depression, and in 1990-91 extensive collection of seed were made in China, allowing provenance testing to be conducted at several sites in the West, notably the Dawes Arboretum (7). These trees are of course still quite young but in view of the extraordinary growth rates observed in this species (many trees planted in 1948 are now well over a meter in diameter), the new material should be coming on the market over the next decade and may well show this species to be useful for timber production.ObservationsRemarksThe interested reader is urged to visit the online publication by Dr. Donald R. Hendricks (7). An older account of the species' discovery follows:The genus was "described in 1941 by the Japanese palaeobotanist, S. Miki, in a paper on the change of flora in eastern Asia since the Tertiary Period. Miki based his new genus on fossil material found in Lower Pliocene deposits in the clay beds of Central Honshu. He realized that two species formerly assigned to Sequoia were distinct from that genus, having similar cones but with decussately arranged scales and a delicate peduncle with scale leaves at the base, whilst the deciduous foliage shoots were somewhat like those of Taxodium. It became evident that the two Japanese species, Metasequoia disticha and M. japonica, were related to other species in widely separated areas, e.g. M. chinensis, from Manchuria and Sakhalin, and M. heerii in North America. Miki's work excited little interest except amongst palaeobotanists but, when a living species of this fossil genus was discovered in Central China in 1945, it became of world wide importance to botanists, arboriculturists, and foresters. "In 1941, T. Kan, of the National Central University, [Nanjing], found a peculiar deciduous tree, at the village of [Modaoqi], south-east of [Wanxian], in [Sichuan], where it was named by the natives [shui-shan]. Owing to the season, no material was collected. It was not until 1944 that specimens were collected, at the same locality, by T. Wang of the Central Bureau of Forest Research, [Nanjing]. Wang thought his specimens belonged to the genus Glyptostrobus, but in 1945 they were examined by C. H. Wu (National Central University) who realized that they belonged to a conifer genus previously unknown in the living flora of China. This opinion was confirmed by Prof. Wan-Chun Cheng of the Central University and Dr. H. H. Hu, Director of the Fan Memorial Institute of Biology, Peiping [Beijing?]. "In 1946, Cheng sent out two expeditions under the leadership of his assistant, Dr. Hsueh, to collect more material and explore the region in search of more trees. Twenty-two additional trees were found and more adequate herbarium specimens were collected. Herbarium specimens were sent to the Arnold Arboretum (Harvard University) whose Director, Prof. E. D. Merrill, was able to obtain funds to finance another expedition to make a fuller investigation of the area and to collect more specimens and viable seeds. This expedition, partly organized by Dr. Hu and led by Dr. Hsueh, was sent out in September, 1946 and spent three months in the vicinity of the previously explored area and in the neighbouring Province of [Hubei]. The expedition found more than 100 large trees growing on slopes, along small streams and near rice paddies. ... "Seeds were received at the Arnold Arboretum early in January, 1948, and many had germinated before the end of the month. Mainly through the generosity of the Arnold Arboretum in sharing its seeds and seedlings, Metasequoia was soon propagated and distributed in many parts of North America and Europe as well as in eastern Asia" (3). Citations(1) Silba 1986.(2) E-mail communication from Robert Van Pelt, 18-Mar-1998. (3) Dallimore & Jackson 1967. (4) Cheng & Fu 1987. (5) Sand, Susan. 1996. The dawn redwood. American Conifer Society Bulletin 13(1): 2-6. (6) Stamp designed by Zeng Xiaolian and issued 10-Mar-1992. Image available at http://www.bupt.edu.cn/stamp/plant/92_3.htm, accessed 12-Apr-1999. (7) Hendricks, Donald R. 1995. Metasequoia: depression, sex, and other useful information. Landscape Plant News 6(2), pagination unknown. Published online at http://www.airnet.net/redwood/rwmeta.html, accessed 12-Apr-1999. (8) Raven, Peter H., Ray F. Evert and Susan E. Eichhorn. 1986. Biology of Plants, 4th ed. New York: Worth. 774 p. (9) B. Bartholomew, D.E. Boufford and S.A. Spongberg. 1983. Metasequoia glyptostroboides -- its present status in central China. Journal of the Arnold Arboretum 64:105-128. See also: Bartholomew, B. 1981."Plant Collecting in China;" University of California Berkeley Botanical Garden Quarterly.
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