The genus Metasequoia was described by the botanist Miki in 1941 from fossils discovered in Japan in Lower Pliocene strata. Living representatives of this new genus were found growing wild in China in the same year, though specimens were not collected from them until 1944. These living trees were described as M. glyptostroboides in 1948.
Metasequoia is allied to Sequoia but the leaves, buds, and branchlets are strictly opposite, whereas in Sequoia the leaves, though arranged in a single plane on the branchlets, are really alternate and spirally inserted; in Metasequoia the primary leaves and the leaf-bearing shoots are deciduous, and the next season’s growths and leaf-sprays are produced from buds on the branches, while in Sequoia the branchlets with their leaves persist through the winter and bear growth-buds at the apex; in Metasequoia the cone-scales are arranged in decussate pairs, spirally in Sequoia. In Taxodium, another related genus, the bald cypress, T. distichum, resembles Metasequoia in producing its foliage on deciduous branchlets, but, at least on coning trees, some branchlets bear scale-like leaves and persist through the winter. Also, in all the taxodiums the leaves are spirally inserted, as in Sequoia.
For a detailed description see Dallimore and Jackson, revised edition, pp. 317-319, where the more important literature is cited. An account by Prof. Merrill of the discovery of the living species will be found in Journ. R.H.S., Vol. 73 (1948), pp. 211-216 (reprinted with additional material from Arnoldia, Vol. 8 (1948), pp. 1-8). There is an interesting chapter on Metasequoia in the work by H.-L. Li cited on page 285.