- Type
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- Difficulty
- Hard
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- Fall
- Sowing
- Plant a sapling
Torreya Nut
Torreya nucifera
Fixed oil and sciadonic acid from the Jeju torreya seed
Torreya nuts are the seeds of a conifer in the yew family. Peel off the fleshy outer coat and you get a kernel shaped much like an acorn. Roasted it turns rich and oily, though it keeps an aroma more of conifer seed than of a familiar nut. The Donguibogam writes it as 榧子, gives 玉榧 as another name and notes that people of the region called it 赤果, and describes stripping the coat and eating the kernel inside.
Year-Round Calendar
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Where It Grows
- Main producer It grows widely in the wild from central Honshu southwards, where it is known as kaya. Oil was pressed from the seeds, and the wood was used as timber.
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Wild population
Wild stands survive at Bijarim on Jeju and in Gangjin, Jangheung and Haenam in South Jeolla. Harvest September, October, November
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- Major producer Chinese torreya (Torreya grandis) is grown on a large scale throughout Zhejiang Province; it is a different species in the same genus as the torreya (T. nucifera).
The wild range of the torreya (Torreya nucifera) is confined to southern Korea and Jeju, and to Japan. The Chinese torreya (T. grandis) grown commercially in Zhejiang, China, is a different species within the same genus, so the two must be distinguished whenever they are shaded onto a single map. Many of Korea's wild stands are designated Natural Monuments, so they are treated as protected forest rather than as growing sites.
- Optimum
- 15~25℃
- Range
- 5~30℃
- Hardiness
- Half-hardy
A warm-temperate evergreen conifer that likes mild conditions and plenty of rain. Its northern limit in the wild is Jeju and Korea's south coast, where winter minimum temperatures never fall very far; when young it tolerates shade and grows extremely slowly.
Harvested 20–30 years after planting. It takes twenty to thirty years from planting until the tree bears fruit, and a full-grown specimen reaches 25 m. This is not a tree that a single year's calendar can express.
In Korea Jeju and the south coast
Jeju and the southern coast of South Jeolla mark the northern limit of its wild range. Groves of ancient trees, such as Bijarim on Jeju, are designated Natural Monuments.
How to grow
- Light
- For open ground.
- Soil and depth
- For open ground.
- Spacing
- For open ground.
- Watering
- Water deeply once a week through summer drought for the first three years.
- Feeding
- Compost around the drip line in March.
- Harvest
- Gather fallen seed from September to November as the fleshy coat splits.
What makes the difference. Growing it is out of reach, so buy well instead: choose plump, oily-looking kernels with no rancid smell. The high fat content means they turn quickly at room temperature, so keep them refrigerated or frozen.
Why this one is harder. It takes 20 to 30 years to bear and reaches 25 m at full size. Old stands such as the Jeju torreya forest are designated natural monuments, so this is not a tree to move around casually either.
Common problems
- Scale insects You will see Small white shells cling to leaves and branches, with sooty mold following What to do Apply horticultural oil in winter and scrape the affected areas
- Root rot You will see Leaves yellow, growth stalls, and the base of the trunk softens What to do Fix the drainage so water cannot sit. Choosing the right site at planting matters most
This page describes how a crop is grown and used. It does not claim health effects for any food, nor is it intended to prevent or treat disease. Component and study notes are references only and do not mean the same result occurs in people. Consult a medical professional about health concerns.
Health Benefits
What the old text says. Torreya nut appears in the Donguibogam's fruit section as 榧子 (bija), recorded as neutral in nature, sweet in taste, and free of toxicity. That is how an old medical text described it, and it stands apart from any modern judgement.
Compound research. Studies have reported conifer-characteristic fatty acids such as sciadonic acid in the fatty acid profile of torreya seed oil. These are analytical findings about composition and do not imply any particular health outcome.
Nutrition
- Fixed oil (About 50 % of the seed by weight) — The rich taste, and the reason it goes rancid quickly
- Sciadonic acid (A fatty acid particular to conifer seeds) — A structure rare among ordinary nuts
Half of it is fat Close to half the kernel by weight is fixed oil, which is why roasted ones leave your fingers greasy. It is not something to eat by the handful — not only for the calorie density, but because several kernels at once can bring on stomach pain or diarrhea. Start with a few, and give children less. Kernels left at room temperature go rancid and start to smell off, so keep them sealed somewhere cool or in the fridge.
Sciadonic acid Torreya oil contains a fatty acid called sciadonic acid. It is a structure found mainly in conifer seeds and rarely in the nuts people usually eat. Compositional studies have reported on its presence and characteristics.
Pairings
○ Simply roasted — Dry-roasting briefly in a pan is the basic treatment. Heat brings the aroma forward and takes the edge off the inner skin's astringency.
○ Honey or grain syrup — Roasted kernels tossed in honey or grain syrup pair the richness with sweetness, close to how it was made on Jeju. Given how fatty they are, a small amount goes a long way.
△ A lot at once — With half the weight in fixed oil, several kernels at once easily bring stomach pain or diarrhea. Even the old text set a daily count rather than leaving the amount open. Start with a few, and give children less.
△ Handling the fleshy outer coat — The fleshy coat around the seed carries resinous compounds, and prolonged bare-handed contact can leave your hands sticky and stinging. Wear gloves when removing it.
△ If you have a nut allergy — Torreya is not a nut most people eat regularly, so it is easy to encounter without knowing how you react. If nuts have caused problems before, start with one or two.
Varieties
- Jeju torreya forest line (Sapling) — The landrace line descended from the old-growth stand around Gujwa-eup on Jeju.
- Korean plum yew (Sapling) — A similar name but a different genus altogether. Do not confuse the two.
Source: Donguibogam, Fruit Section (榧子) · National Institute of Forest Science · Cultural Heritage Administration natural monument records