Hinoki: A Revered Conifer

 Hinoki is one of Japan's most beloved conifers, for its grace and incomparable fragrance. Photo: Aleks Monk

Hinoki is one of Japan's most beloved conifers, for its grace and incomparable fragrance. Photo: Aleks Monk

By Corinne Kennedy

Among the many conifers in our Seattle Japanese Garden is Chamaecyparis obtusa* (known in Japan as hinoki -- hence its common name Hinoki False Cypress).  It’s one of Japan’s most significant trees -- revered for centuries for its beautiful, durable wood and the fragrant essential oils of its bark, wood and foliage.  With its rich, straight grain – and resistance to splitting, warping and rot -- it’s been an important building material in Japan:  in construction, tools, sculptures, and civil engineering.  Traditionally, it was used in Shinto ceremonies & purification rituals, to build shrines & temples, and to construct fragrant tubs for bathing. 

Well-built hinoki structures can last 1000 years – and some buildings/artifacts are even older.   Horyuji Temple in Nara, Japan, is a UNESCO World Heritage Site, and home to some of the oldest surviving wooden structures in the world – including its pagoda, built about 600 AD.

Hinoki is native to central and southern Japan, but its long usefulness has led to its loss in the wild, where it’s considered an endangered species.  Rare throughout its traditional range, it exists only in remnant stands.  Nevertheless, planted trees are very common today in Japan – in plantations, parks and gardens.  Very large specimens are uncommon -- to be found only at temples and shrines.

Hinoki means “cypress,” and this word dates to preliterate Japan -- thus it predates hi (fire) and ki (tree).  It’s been claimed that the meaning of hinoki is “fire tree,” but this interpretation is probably incorrect.

Chamaecyparis obtusa grows at a medium rate (about one foot annually) and forms a tall, slender cylinder or pyramid with spreading branches and pendulous, flattened, frondlike branchlets.  Centuries-old trees may exceed 150 ft. in height.

The scale-like dark green or blue-green leaves, with whitish markings underneath, are blunt at their tips.  Pollen cones and seed cones are held separately, but on the same tree (the term for this is “monoecious”).  The 1/3 inch, nearly round seed cones start out a bright green, then turn brown with time.  The smaller, conical, red-brown pollen cones grow singly on the outer twigs.  Their pollen is a major cause of spring “hay fever” allergies in Japan.  Many seedlings are produced, but they seldom survive, so Chamaecyparis obtusa is not considered a “weedy” tree.  The bark is reddish-brown to silvery, and on young trees peels off in thin strips.  Older trees have thicker, more compact bark.

Chamaecyparis obtusa grows best in a moist, well-drained, neutral to acid soil, and in a somewhat humid climate.  It prefers a sunny location, protected from wind, but young trees tolerate some shade.  Plantation forests provide inadequate habitat for most plants and animals.  However, some ferns, mosses and woody plants do survive beneath their canopy.

Hinoki essential oil consists of many aromatic chemicals -- including “hinokitol,” a compound that’s low in toxicity and a “bacteriostatic agent” (one that inhibits bacterial growth).  It’s also found in other members of the cypress family, the Cupressaceae.  The essential oil is used in aromatherapy -- and as a natural remedy in grooming aids such as toothpaste, hair products and perfumes.  Hinoki wood is still used in building today – but only in high end products, because of its expense.

Chamaecyparis obtusa, the species plant, was introduced into Europe in 1847, and into the U.S. in 1862.  Many hinoki cultivars (cultivated varieties, developed in Japan and elsewhere) have been produced, and are grown in temperate climates worldwide -- in private as well as public plantings.  The cultivars are widely available at Pacific Northwest nurseries, and are commonly planted in our gardens – and not only those designed in a Japanese style.  One of the taller cultivars is C. obtusa ‘Gracilis’ (Slender Hinoki False Cypress), slower-growing but similar in habit to the species.  Most popular among the smaller cultivars is C. obtusa ‘Nana Gracilis’ (Dwarf Slender Hinoki False Cypress), which grows to about 4 feet tall in 10 years and 8 feet at maturity.  Both are planted in Area W of our Seattle Japanese Garden. There are dozens of other cultivars, many of them suitable for bonsai because of their slow growth and irregular habit.  The Weyerhauser Bonsai Garden in Federal Way, WA, has an excellent example.

I love hinoki’s fragrance and the diversity of its many cultivars – in size, shape, habit and color.  Some are very short and squat, but most have an elegance of form that’s characteristic of Japanese aesthetics -- and brings a hint of Japan to even the plainest of our gardens.

*The former genus name was Retinospora, sometimes spelled Retinispora.

Corrinne Kennedy is a Garden Guide and a frequent contributor to the Seattle Japanese Garden blog.