Torreya nucifera Seeds | Japanese Nutmeg Yew
LATIN NAME: Torreya nucifera
COMMON NAME: Japanese Nutmeg Yew
Plant Profile
A block of this tree’s wood, sawn thin and planed so the grain runs straight down the long axis, is what the finest boards for the game of Go and for Japanese chess are made from, and the slowness of the tree is part of the reason. A trunk thick enough to yield such a board takes decades to grow, and the pale, fine-grained timber has to be cut, dried and seasoned with equal patience before it is worth working. The same tree carries seed that look and taste close enough to a nutmeg to have earned it a name, and those two things, a board and a kernel, are the reasons the species has been planted beside temples and houses for many generations.
The foliage is stiff and flat, arranged in two ranks along the shoot, glossy dark green above and marked below with two pale bands of stomata. Each needle ends in a short hard point, which is the surest way to tell a nutmeg yew from the soft-tipped plum yews that share its woodland.
Fertilised ovules take two seasons to ripen, so a branch in late summer carries green developing seed alongside the purple-brown ones that are ready, and the crop is never gathered all at once. Each seed sits in a fleshy aril that turns from green to a dull violet as it matures, and inside that lies a hard woody shell and then the kernel. The flesh is oily and smells strongly of resin when the seed is handled; squirrels and other rodents move the seed away from the tree and bury them.
Pressed kernels give an oil that is stable enough to keep without refrigeration in a cool store. In its native range the seed are also salted, roasted or pickled and eaten as a snack, a use that requires the woody shell to be cracked without crushing the kernel inside. Because the fruit cannot be harvested mechanically without damage, the nut trade around this genus has stayed hand work.
Science & Biotechnology
The needles of the genus are noted for biflavones, the linked flavonoid dimers built on an amentoflavone skeleton, and these pigments and antioxidants occur alongside a range of diterpene hydrocarbons in the leaf tissue. The kernel is where the plant places its energy: it is rich in oil, dominated by oleic and linoleic acids, with a small fraction of saturated fat and a useful content of tocopherols, which is why the seed oil has been both a cooking fat and a lamp oil in its native range.
Taxonomists have sequenced complete chloroplast genomes for several nutmeg yews, and that work settled where the genus sits within the yews and how it relates to the plum yews, with which it was once grouped in a separate family. For growers, the more useful research is in propagation. Seedlings from an open-pollinated tree vary in habit and in the size of the kernel, and the tree is slow to reach flowering, so somatic embryogenesis from mature embryos has been developed to multiply selected material without waiting on a juvenile phase.
Uses & Benefits
Three uses have followed the tree through its history. The kernel supplies food and oil, and the seed pressed into salt or rice-wine lees makes a bitter, resinous preserve that is a seasonal delicacy. The timber, which is close-grained, works easily and takes a fine finish, goes into boards for Go and Japanese chess, into indoor joinery and into carved utensils where a pale surface is wanted. The tree is also planted as a specimen for the density of its crown and its tolerance of shearing.
Growing from Seed
Nutmeg yew seed should be sown fresh, because the oily kernel loses viability once it has dried out. Clean the flesh from the shell and soak the seed in water overnight, then sow it about twenty-five millimetres deep in a deep pot of loam-based compost mixed with a third of coarse sand and a little leaf mould. A cool moist period is needed before the shoot appears, so leave the pot in a shaded frame through a winter, covered with mesh to keep rodents out; a seed that sends up nothing in the first spring may still come through in the second. Deep pots matter, because the seedling makes a long taproot before it makes much top growth, and moving the plant afterwards is risky.
Keep the compost moist but well drained, and site young plants in light shade for their first two seasons before moving them into sun. Space permanent plants at least four metres apart, since the crown spreads with age. Water steadily through dry summers, mulch with leaf mould to keep the roots cool, and feed sparingly with a slow-release fertiliser in spring rather than a rich liquid feed. The species is hardy in a cold winter once established, but a young plant benefits from a windbreak for its first cold season. Prune only to shape a leader or remove a damaged branch, cutting in late winter. There are few pests, though scale insects and aphids can appear on the undersides of the needles under glass, and the seed crop is otherwise claimed by squirrels before it is ready to gather.
Our Take
Buy this seed only when you can give it a shaded frame, a deep pot and patience, and grow the first years slowly. The Chinese relative behind the nut trade in the same genus, Torreya grandis, is worth sowing alongside it, and the plum yews of the same woodlands, such as Cephalotaxus fortunei, will establish in deeper shade than a nutmeg yew ever will. Where the soil is damp and lime-free, the whorled foliage of Sciadopitys verticillata makes a fine companion, since it takes the same sheltered woodland conditions.
Related Reading
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