Kaya, Japanese torreya
Torreya nucifera

Family: Cephalotaxaceae

What it is like

Torreya nucifera is an evergreen Tree growing to 20 m (65ft) by 10 m (32ft) at a slow rate. See above for USDA hardiness. It is hardy to UK zone 7. It is in leaf all year, and the seeds ripen from September to November. The species is monoecious (individual flowers are either male or female, but both sexes can be found on the same plant) and is pollinated by Wind. The plant is self-fertile. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in full shade (deep woodland) or semi-shade (light woodland). It prefers moist soil.

Height (m): 20

Where it is found

Moist valley bottoms.

E. Asia - C. and S. Japan.

Conservation Status:

Countries/locations it is found in

How it is used

Food

Rating: 5

Seed - raw, cooked or used in confectionery. An agreeable sweet slightly resinous flavour. An aromatic flavour, it is much relished and is eaten in quantity though it is said to be laxative if eaten in excess. An edible oil is obtained from the seed. Used in cooking.

Oil: Oil

Seed: includes nuts, cereals, peas and beans.

Medicine

Rating: 2

The seeds are anthelmintic. They are used in the treatment of several parasitic conditions including hookworm, tapeworms, pinworms and roundworms. The plant is anodyne, carminative, digestive, laxative and pectoral.

Anodyne: Relieves pain, it is milder than an analgesic.

Anthelmintic: Expels parasites from the gut.

Carminative: Reduces flatulence and expels gas from the intestines.

Digestive: Aids digestion.

Laxative: Stimulates bowel movements in a fairly gentle manner.

Pectoral: Relieves respiratory diseases, a remedy for chest diseases.

Other

Rating:

Oil: Vegetable oils have many uses, as lubricants, lighting, soap and paint making, waterproofing etc. This does not include the edible oils unless they are also mentioned as having other uses.

Management: Standard: Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.

Regional Crop: These crops have been domesticated and cultivated regionally but have not been adopted elsewhere and are typically not traded globally, Examples in this broad category include perennial cottons and many nuts and staple fruits.

Staple Crop: Protein-oil: (16+ percent protein, 16+ percent oil). Annuals include soybeans, peanuts, sunflower seeds. Perennials include seeds, beans, nuts, and fruits such as almond, Brazil nut, pistachio, walnut, hazel, and safou.

Management: Standard: Plants grow to their standard height. Harvest fruit, seeds, or other products. Non-Destructive management systems.

Regional Crop: These crops have been domesticated and cultivated regionally but have not been adopted elsewhere and are typically not traded globally, Examples in this broad category include perennial cottons and many nuts and staple fruits.

Staple Crop: Protein-oil: (16+ percent protein, 16+ percent oil). Annuals include soybeans, peanuts, sunflower seeds. Perennials include seeds, beans, nuts, and fruits such as almond, Brazil nut, pistachio, walnut, hazel, and safou.

Carbon Farming: Plants that can be a critical part of the solution to climate problems. The Carbon Farming Solution - Eric Toensmeier.

How it is grown

Succeeds in ordinary garden soil, tolerating some lime. Prefers an acid soil. Dislikes wind exposure. Requires a sheltered position and either high humidity or a moist riverside soil. Tolerates woodland shade very well. Requires hot, very humid summers for best growth. Trees are probably not hardy in all parts of Britain, but should succeed quite far north. A tree at Wakehurst Place was 11 metres tall in 1970. A shrub growing in the shade of coniferous trees at Kew was about 2.5 metres tall and 4 metres wide in September 1993, it was carrying a very heavy crop of fruit. No fruit was formed in 1994. A specimen at Cambridge Botanical Gardens was 6 metres tall and 6 metres wide, it was carrying an enormous crop of seed in the late summer of 1996. This plant has an excellent potential as a nut crop in Britain. Sometimes cultivated for its edible seed in Japan, the variety 'Shibunashigaya' is considered to be the best for seed production. The seed takes two summers to mature. Plants are dioecious so both male and female plants are required if seed is to be produced. Occasional trees are monoecious with dioecious branches. Solitary trees have been seen on a number of occasions with heavy crops of fertile seed, so it would appear that the tree is not dioecious.

Propagating it: Seed - best sown as soon as it is ripe in a cold frame. Some of the seed should germinate in the following spring though much of it might take another 12 months. Stored seed requires a period of cold stratification and can take 18 months or more to germinate. Prick out the seedlings into individual pots as soon as growth is observed and grow them on in light shade in the greenhouse for at least the next couple of winters, making sure to pot them on into larger pots as and when required. Plant them out into their permanent positions in early summer when the plants are at least 20cm tall. Cuttings of half-ripe shoots in late summer. Cuttings do not grow well. Layering.

Best place to grow: Woodland Garden Secondary; Sunny Edge; Dappled Shade; Shady Edge; not Deep Shade;

Habit: Tree

Hardiness: 6-8

Growth: Slow

Soil: Light (sandy), medium, heavy (clay)

Shade: Full shade, semi-shade

Moisture: Moist

Things to keep in mind

Its other names

Local names

Synonyms

Taxus nucifera.