Carya hunanensis Seeds | Hunan Hickory
LATIN NAME: Carya hunanensis
COMMON NAME: Hunan Hickory
Plant Profile
Hunan hickory is one of the Chinese hickories that botanists know better than gardeners do, and its interest lies in what it might contribute rather than in what it already is. It is a deciduous tree of the walnut family, fifteen to twenty-five metres, with pinnate leaves of five to seven leaflets, a straight grey trunk and a broad crown. The nuts are small, thick-shelled and hard to crack, with a kernel that is sweet but laborious to extract, and they sit in thick, four-valved husks that split in autumn. It grows in the hills of Hunan, Guangxi and Guizhou, in mixed broadleaf forest on acid soils, and it is nowhere abundant. The timber is hard, shock-resistant and useful for tool handles, though the tree is rarely cut in quantity. It is close to the Chinese hickory, Carya cathayensis, and some authors treat it as a variety of it.
Science & Biotechnology
Carya hunanensis sits in section Sinocarya, the Asian hickories, a group that diverged from the American pecans and shagbarks and that carries a smaller number of leaflets and thicker nut shells. Its chromosome count is 2n = 32, like the rest of the genus, and it hybridises with C. cathayensis where the two meet, which complicates the delimitation of both species. The nut is rich in oil, mostly oleic and linoleic acids, and in tocopherols, and the kernel is a source of edible oil in its native districts. The tree is heterodichogamous in the way of hickories, with male and female flowers maturing at different times on the same tree, which promotes outcrossing, and it depends on wind for pollination. Its thick shell is a defence against rodents and birds, and it also makes the nut commercially unattractive.
Uses & Benefits
The nuts are eaten locally, roasted or pressed for oil, and the oil is used for cooking and for lamps in the villages where the tree grows. The timber is hard and takes shock well, and goes into tool handles, sporting goods and furniture, but the volumes are small and the species is not managed as a timber crop. The tree’s main value may be genetic: it is a disease-resistant relative of the commercial hickories, and it has been used in Chinese breeding work as a source of hardiness and nut quality. In gardens it is a collector’s tree, grown for the handsome pinnate foliage, the yellow autumn colour and the novelty of the nuts. It is slow to bear, often ten years from seed, and it needs a deep soil and a long season to ripen the wood.
Growing from Seed
Sow fresh nuts in autumn, two to three centimetres deep in a deep pot, and leave them outdoors for winter; they need cold, moist stratification and they must not dry out. Protect them from squirrels and mice. Germination is in spring, and the seedling develops a long taproot in the first season, so use a deep container and do not trim the root. Grow it in full sun in deep, well-drained, slightly acid soil, and keep it free of competition for the first three years. Plant out at forty to sixty centimetres, in a site with room for a twenty-metre crown, and water through the first two summers. Expect slow growth and a long wait for the first nuts, and do not expect the crop to be worth the cracking.
Our Take
A collector’s hickory with hard-shelled nuts and useful genetics, grown for foliage and novelty rather than for harvest. Give it deep soil and a decade.
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