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China fir, Robert Brown ex Richard & Achille Richard in Achille Richard  1826


Evergreen trees with thin, fibrous bark peeling in irregular flakes on single, forked, or multiple trunks, regenerating by stump sprouting. Crown narrow, oval, witch well-spaced whorls of short, horizontal branches. Shoot system weakly differentiated into permanent long shoots and short shoots that are shed intact after a few years. Resting buds roughly spherical, wrapped loosely by narrowly triangular, flat, leaflike bud scales. Leaves arranged in dense spirals but brought into two loose rows on either side of the stem on horizontal branches by twisting at the point of attachment with the twig, the bases running down the twigs and completely clothing them. Leaves needlelike, sword-shaped, flat, often bowed up in the middle to form an arch, minutely toothed along the margin, gradually tapering to the sharp, stiff tip, and slightly narrowed at the attachment to the twig.

Plants monoecious. Pollen cones cylindrical, in a starburst cluster of 15-30 from a common bud at the tip of an ordinary leafy twig. Each cone consisting of 30-100 spirally arranged pollen scales. Scales with a thin stalk and three pollen sacs at the base of the rounded-triangular, toothed, blade. Pollen grains small to medium (30-45 µm in diameter), more or less spherical, with an obscure, round germination pore and minute bumps over the whole surface. Seed cones single or in clusters of up to four at the tips of foliage shoots, often later displaced from the tip by new shoots growing out beyond them, broadly egg-shaped, maturing in their first season. Seed scales numerous, spirally arranged, thin, woody, triangular, minutely toothed, and dominated by the bract portion, the fused fertile portion reduced to a small, lobed pad of tissue supporting the (two or) three seeds. Seeds oblong, somewhat flattened, with two narrow wings derived from the seed coat extending the whole length of the body. Cotyledons two, each with one vein. Chromosome base number x = 11.

Wood strongly fragrant, soft, light and weak but extremely decay resistant, with a broad white sapwood sharply contrasting with the dark yellow to reddish brown heartwood. Grain moderately even and fine, with well-defined growth rings marked by an abrupt transition to a narrow band of denser latewood with much smaller, thicker-walled tracheids. Resin canals absent but with fairly abundant individual resin parenchyma cells scattered through the growth increment, especially in the outer half, and often in an open ring just inside the latewood.

Stomates in two prominent broad stomatal bands underneath and with more or less conspicuous ones on the upper side. Each stomate tucked under and partly hidden by the four to six irregularly shaped subsidiary cells, which are not surmounted by a Florin ring. Leaf cross section with a single-stranded midvein accompanied beneath by a large resin canal and to the sides by short wings of transfusion tissue. Often with an additional resin canal on either side about two thirds of the way put toward the margin from the midrib. Photosynthetic tissue forming a weakly developed palisade layer beneath the upper epidermis and adjoining nearly continuous (except beneath stomates) hypodermis. Spongy mesophyll with scattered clusters of sclereids, some of which mark the boundary between the spongy and palisade tissues.

Two species in China. The wood of China fir, like that of many other Cupressaceae, is highly decay resistant and is a premier timber tree in China, being used as a coffin wood and for many other purposes. As a result, the trees are grown in China in plantations and forests managed for timber production. Elsewhere, they are moderately common in horticulture in warm temperate regions such as the western coast of North America or the southeastern United States. They are not always the most handsome trees, tending to have somewhat ragged crowns, and they are messier than the average conifer, with their masses of large shed shoots. Perhaps this explains why there has been so little cultivar selection, with only a handful of dwarfs and foliage color variants. The genus honors James Cunningham (d. ca. 1709), who was a physician with the East India Company in China when he acquired a specimen of Cunninghamia lanceolata for his garden in 1702 and sent specimens of it and other Chinese plants back to correspondents in England.

Because of the resemblance of the foliage to that of Araucaria bidwillii, some early taxonomists associated Cunninghamia with the Araucariaceae, but most authors, then as later, placed it with redwoods in the Taxodiaceae, now included in the Cupressaceae. Foliage and cones of Cunninghamia, nonetheless, are distinctive in the family, and it appears to have no particularly close relationships, although it is closest to its geographic neighbor, Taiwania. Instead, DNA studies suggest that its ancestors were the first members of the family to become distinct. This is borne out by the fossil record, which includes many well-preserved seed cones. Although fossils attributable to Cunninghamia itself only go back to the beginning of the Tertiary, structurally similar cones (Cunninghamiostrobus and Elatides) extend back to the late Jurassic, earlier than any other extant lineage of the family.

Despite differences in mature appearance, early development of cones in Cunninghamia is similar to that in Cryptomeria and other fairly distantly related genera of Cupressaceae, with each seed developing on a separate seed scale lobe (often rather toothlike early on). Later, development diverges as the bract undergoes massive enlargement in Cunninghamia unmatched by the seed scale lobes, while the latter also enlarge and become more or less united side to side in the remaining genera. Cunninghamia also shows a clear structural similarity (homology) between the seed cones and the clusters of male cones. The whole cluster has the same position at the end of a branch as the seed cones and also consists of a similarly shaped spiral of similarly shaped bracts. Of course, in the pollen-producing structure, each bract has a whole simple pollen cone in its axil consisting of dozens of pollen scales, each bearing three pollen sacs, rather than the three lobes, each bearing a single ovule (morphologically equivalent to a pollen sac as both are (based on) sporangia) that make up the seed scale portion of the cone scale. Still, in their early stages, before pollination, when they are still closed up like large buds, the two structures are remarkably similar. Occasionally, mixed cones occur in which the lowermost bracts subtend pollen cones while all the rest bear ovules in the normal fashion of seed cones.  




Attribution from: Conifers Garden