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Bristlecone hemlock, H.H. Hu ex C.N. Page  1988


Evergreen, single-trunked or multistemmed trees. Bark scaly, rough, becoming ridged and furrowed with age. Crown egg-shaped and open, with slender horizontal to gently rising branches concentrated near the top of the trunk’s annual growth increments and with a drooping leader. Lateral branching dense, with a tendency toward weakly developed persistent short shoots borne on the long shoots. Winter buds well developed, scaly. Leaves spirally arranged, sometimes partly two-ranked but mostly radiating around the twigs, widely spaced on long shoots. Each leaf needlelike, linear, flattened to shallowly triangular in cross section, abruptly narrowed to a short petiole that attaches to a small, weak, decurrent woody peg on the twig.

Plants monoecious. Pollen cones in umbrella-like clusters emerging from single terminal buds at the tips of twigs. Each pollen cone slender-stalked, oblong with 25-40 pollen scales. Each scale heart-shaped with two very large pollen sacs. Pollen grains with two bladders. Seed cones erect, single in the axils of leaves or at the tips of short axillary twigs, maturing in a single season but persisting several years after releasing the seeds, ellipsoid-cylindrical before opening. Bracts about half as long as the roundly diamond-shaped thin seed scales, just visible beyond the ones that overlap them. Seeds in pairs, each with a slightly longer asymmetric wing derived from the scale. Cotyledons not reported. Chromosome base number x = 12.

Wood with well-defined growth rings marked by a sharp transition between early- and latewood. Vertical resin canals in the latewood becoming more frequent with age.

With a few lines of stomates near the midrib above and more numerous ones filling most of the surface beneath. Structure of the stomates not reported. Leaf cross section with a single resin canal beneath the single-stranded midvein. Photosynthetic tissue with a partial palisade layer beneath the upper epidermis and adjoining layer of hypodermis pierced by openings connecting the stomates to the spongy mesophyll that fills the bulk of the leaf.

One species in south-central China. The sole species of Nothotsuga was originally described as a Tsuga and is often retained in that genus, with which it has many points of similarity. It differs from all hemlocks, however, in the position and arrangement of the pollen and seed cones, which more closely resemble those of Keteleeria and Pseudolarix. Wood and bark structures also show strong similarities to Keteleeria and Tsuga but support the separation of Nothotsuga from both genera. Nothotsuga longibracteata in not in general cultivation, and there has been no cultivar selection. The known fossil record is meager, but extends back to the Pliocene of Japan and Russia, about 3-5 million years ago.




Attribution from: Conifers Garden