thumb|Close-up of hinoki cypress needles

Chamaecyparis obtusa (Japanese cypress, hinoki cypress or hinoki; or , ) is a species of cypress native to central Japan in East Asia, and widely cultivated in the temperate northern hemisphere for its high-quality timber and ornamental qualities, with many cultivars commercially available.

It once existed outside Asia with a range that stretched to Germany during the Miocene. Hinoki grows primarily on the islands of Honshu, Shikoku, and Kyushu. The main massifs are formed in mountainous regions with a moderately humid climate, at altitudes from 300 to 1,500 meters above sea level.

Description

It is a slow-growing tree which may reach tall with a trunk up to in diameter. The bark is dark red-brown. The leaves are scale-like, long, blunt tipped (obtuse), green above, and green below with a white stomatal band at the base of each scale-leaf. The cones are globose, in diameter, with 8–12 scales arranged in opposite pairs.

The plant is widespread in Japan. The related Chamaecyparis pisifera (sawara cypress) can be readily distinguished in its having pointed tips to the leaves and smaller cones. Those marked have gained the Royal Horticultural Society's Award of Garden Merit (confirmed 2017).

  • 'Crippsii' makes a broad conic golden-green crown with a vigorous leading shoot, growing to or more tall
  • 'Fernspray Gold' – , arching sprays of green/yellow branches
  • 'Kamarachiba' – spreading shrub, tall by wide, sprays of yellow-green
  • 'Kosteri' – sprawling dwarf to tall by wide, with brilliant green foliage
  • 'Lycopodioides' reaches up to tall, with somewhat fasciated foliage
  • 'Minima' – under after 20 years with mid-green foliage
  • 'Nana' – dark green, rounded dwarf shrub to
  • 'Nana Aurea' – , golden tips to the fans and a bronze tone in winter
  • 'Nana Gracilis' – crowded fans of tiny branches producing richly textured effects; often cited as dwarf but has reached tall in cultivation in Britain
  • 'Nana Lutea' – compact, slow-growing, golden yellow selection which has become very popular; yellow counterpart to 'Nana gracilis'
  • 'Spiralis' is an erect, stiff dwarf tree
  • 'Tempelhof' growing to with green-yellow foliage that turns bronze in winter
  • 'Tetragona Aurea' grows to around tall, with a narrow crown and irregular branching, the scale leaves in 4 equal ranks and branchlets tightly crowded, green and gold
  • 'Tsatsumi Gold' – , contorted branches, yellow-green foliage

Chemistry

The lignans chamaecypanones A and B, obtulignolide, and isootobanone can be found in the heartwood of Chamaecyparis obtusa var. formosana. The biflavones sciadopitysin, ginkgetin, isoginkgetin, podocarpusflavone B, 7,7<nowiki></nowiki>-O-dimethylamentoflavone, bilobetin, podocarpusflavone A, 7-O-methylamentoflavone, amentoflavone, hinokinin and hinokiflavone have been confirmed in the leaves of the plant. Chamaecydin was first discovered in the seeds of C. obtusa. The essential oil of Chamaecyparis obtusa contains a wide range of chemical compounds, including but not limited to the following: sabinene, elemol, myrcene, limonene, terpinen-4-ol, eudesmols, α-terpinyl acetate, α-terpinolene, α-terpineol, 3-carene, α-pinene, γ-terpinene, camphene, bornyl acetate, 1-methyladamantane, cuminol, eucarvone, 2-cyclopenten-1-one, 3,4-dimethyl-, 1,3-dimethyl-1-cyclohexene, calamenene, τ-muurolol, borneol, α-cadinol, β-thujaplicin. Some of these compounds are fragrances or intermediates used in the fragrance industry. Thus, the C. obtusa essential oil is used in perfumery and personal care products, such as soaps, shampoos, cosmetics.

Essential oil distilled from its wood is uniquely scented and highly valued.

Pollen

Hinoki pollen can cause pollinosis, a specific type of allergic rhinitis. Chamaecyparis obtusa, along with Cryptomeria japonica (sugi, Japanese cedar), is the leading source of allergic pollen in Japan and a major cause of hay fever in Japan.

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File:Chamaecyparis obtusa 'Nana gracilis'.jpg|C. obtusa 'Nana Gracilis'

File:Kyoto Toji Hiwadabuki C0990.jpg|Cypress bark is used as a traditional roofing material (hiwadabuki) at Tō-ji in Kyoto

File:Haeckel Coniferae Chamaecyparis obtusa.jpg|Illustration

File:Chamaecyparis Obtusa bonsai.JPG|Bonsai

File:Japanese cypress woods C032473.jpg|

File:Chamaecyparis obtusa 01.jpg|Tanzawa Mountains, Japan

File:Chamaecyparis obtusa2.jpg|Foliage; underside showing white stomatal lines

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References