Scientific name: Torreya nucifera

Historical Synonyms: Taxus nucifera, Torreya nuda, Podocarpus nuciferus, Caryotaxus nucifera, Torreya ascendens, Foetataxus nucifera, Tumion nuciferum, Torreya macrosperma, Torreya fruticosa, Torreya igansis

Common name: Japanese nutmeg tree, nutmeg yew, kaya (Japanese), bija (Korean)

Family: Taxaceae

Native Range: Central and Southern Japan, Islands of the southern Korean peninsula

Conservation status: Least Concern

In the Washington Park Arboretum: 243-82-A+B along the lower trail, just north of the Preston Memorial, in grid 23-1W. 500-77-A in the Woodland Garden, at the west end of the upper pond, in grid 32-2E. X-89-A below the Middle trail, in grid 18-2E

Habit: Large tree or large, multi-trunked shrub (slow growing)

For those unfamiliar with the genus Torreya, you may imagine a conifer that has the lush and appealing two-ranked foliage of grand fir (Abies grandes) only with the leaf tips ending in sharp points ala spruce (Picea), growing often in the habit of a yew (Taxus) in cultivation. The Japanese name for T. nucifera is kaya, meaning ‘yew’.

Torreya nucifera differs from species of Taxus in multiple ways. Though often a large shrub, T. nucifera may grow to 75 feet tall in the wild. While Taxus have their seeds wrapped in a bright red aril which attracts birds to spread the seeds, Torreya seeds are found inside a fleshy green (sometimes flushed purple) drupe-looking fruit (also and aril). The seeds of Torreya take 18 months to ripen, compared to 6-9 months for Taxus. And unlike Taxus, Torreya leaves have those stand-offish pointy tips.

Along with 4 Asian species of Torreya, there are 2 species native to the United States, one on each coast. T. taxifolia (common names include ‘gopher wood’) is a critically endangered species native only to a small area of NW Florida and SW Georgia along the Appalachicola river, a result of extensive glaciation along the eastern US coast. Cutting and a fungal disease has reduced the wild population to between 500 and 1000 individuals, and the IUCN lists T. taxifolia as the rarest conifer in North America.

T. californica is an endemic species in the coastal ranges and the Sierra Nevada. This species is listed as ‘Vulnerable’. The champion California nutmeg (aka stinking cedar) was measured at 130 feet tall and 13.5 feet in diameter, but was stolen by timber thieves. Age was estimated at between 275 and 286 years by counting the stump’s rings.

In Japan, the seeds of the nutmeg yew are desirable to be roasted and eaten or used to produce a cooking oil with a subtle nutty flavor highly prized in some circles for tempura. The ‘nuts’ are rich in vitamin E as well as sciadonic acid, known to reduce cholesterol. Sciadonic acid is also found in seeds of such conifers as pine (multiple Pinus species), Chinese arborvitae (Platycladus orientalis), ginkgo (Ginkgo biloba) and umbrella pine (Sciadopitys verticillata).

During the Joseon era (1392-1897) in Korea, the nuts of bija were valued for their antiparasitic properties. During this era, temples were required to grow this tree for the parasiticide. Today, it has been shown that an extract from T. nucifera seeds damages the mitochondria of Acanthamoeba (amoeba parasites of the eye) which cause Acathamoeba keratitis, a common affliction of contact lens wearers, and may someday lead to a new treatment.

Nutmeg yew wood is also highly valuable for cabinetry, furniture and boards for the Chinese game, Go. Highly valued Go boards are made from logs between 200 and 800 years old and can be priced as much as $100,000 US dollars. The demand for the wood has led to conservation measures in Japan where regulations now only allow harvesting of trees that have already died from natural causes.

The first description of nutmeg yew by a western scientist came in 1712 by the German naturalist and physician Englebert Kaempfer who traveled through Asia, sometimes as a surgeon with the East India Company. Kaempfer described the plant as Taxus nucifera in Amoenitatum exoticarum. The genus Torreya comes from the botanist George Walker Arnott in 1838, named in honor of John Torrey, the American botanist. The specific epithet nucifera means ‘bearing nuts’.

The crown of the nutmeg yew is dense and conical when young, becoming more rounded and irregular with age. The species is known as sub-dioecious, meaning that each plant will be dominated by either male or female cones, though both will be present in some amount. Female cones are found singly, paired or in clusters, with a purplish blush when ripe. Accounts of the fragrance of the foliage when crushed conflict between “not aromatic”, “pleasantly fragrant” and “pungent and disagreeable”.

In the wild, the nutmeg yew is found scattered in temperate, mixed broadleaf and coniferous forests. In cultivation T. nucifera prefers partial shade in all but the coolest summer areas. Preferred soils are slightly acidic which do not dry out. Reports of cold hardiness vary between USDA zones 6 (-10 F – 0 F) and 7 (0 F – 10 F).

There are two areas of the Washington Park Arboretum where Torreya nucifera viewing is easy. In the Woodland Garden, standing at the outflow of the upper pond, look south across the stream to see a 45 year old specimen, 500-77-A. For specimens 243-82 A and B, travel south from the Dan Hinkley Asian Maple collection on the Lookout Loop, lower trail. Just before you reach the Preston Memorial patio, they are located just below the trail on the west side.

Sources:

Auders, Aris G. and Spicer, Derek P., Encyclopedia of Conifers, Kingsblue Publishing Limited, 2012, pgs 1403-1407.

Hsu, Eric, Tree of the Year: Torreya nucifera, International Dendrology Society, www.dendrology.org.

Britannica, www.brittanica.com.

National Library of Medicine, https://pubchem.ncbi.nlm.nih.gov.

Missouri Botanical Garden, www.missouribotanicalgarden.org

American Conifer Society, https://conifersociety.org.