Thujopsis dolabrata: An Uncommon Conifer with Bold, Shiny Green Foliage, Silvery-white Underneath

By Corinne Kennedy

While similar to our western red cedar, it has bolder foliage that is glossy, deep forest green above, with beautiful, startling white markings” beneath. Leaves are held in wide, flat branchlets and the overall effect is richly textural. The distinctive foliage has inspired two curious common names:  deerhorn cedar and battle ax cedar. (Dolabrata means hatchet in Latin.) https://www.greatplantpicks.org/plantlists/view/1556

Thujopsis dolabrata in Area B, by the path at the Garden’s entrance. (photo: Aleks Monk)

One of my favorite conifers in the Seattle Japanese Garden is Thujopsis dolabrata (thew-YOP-sis DOL-o-bra-ta), known by various common names, including hiba arborvitae, hiba cedar, false arborvitae, and lizard tree. Its shiny, scale-like green foliage has striking white undersides and an unusual, almost plastic appearance. Our Garden has three specimens, two outside the Garden near its entry courtyard and a slightly taller one in Area B – inside the gate, on the west side of the path.

Endemic to Japan, Thujopsis dolabrata is a medium to large evergreen conifer – and one of the most unique trees in the Cypress family (Cupressaceae). There is only one species, dolabrata. It closely resembles a related genus, Thuja (true arborvitae), and in fact, the word Thujopsis, which includes the Greek suffix opsis, means “like a Thuja”. Hiba arborvitae, however, has larger leaves and broader, flatter fanlike branchlets.

In the wild, false arborvitae grows in forested regions of Japan where the climate is cool and moist.  It appears in evergreen and mixed evergreen-deciduous forests, from lowlands to mid-elevation mountain slopes, often in association with northern Japanese hemlock (Tsuga diversifolia). Two Japanese names indicate its resemblance to hinoki false cypress (Chamaecyparis obtusa) – hiba and asunaro. The latter word is believed to derive from the phrase, asu wa hinoki ni narou (“tomorrow it will become a hinoki cypress”).

Thujopsis wood is aromatic and durable, and was used historically in construction, woodcarvings, and lacquerwork. During Japan’s feudal period, it was valued as one of the “'five sacred trees of Kiso”, and reserved for the Emperor’s use. Its primary importance, however, is as an ornamental tree – planted around temples and in gardens, and as a hedge.

In its native habitat, this dense, pyramidal conifer may eventually attain a height of 100 feet, maturing with a conical crown. Under cultivation, 30-50 feet tall is more typical.  Slow-growing and usually multitrunked, trees may remain low, rounded shrubs for many years before beginning their upright growth. Flattened branches are held almost horizontally, turning upwards at the tips. With time, the reddish-brown bark peels in thin vertical strips.

The bold foliage is shiny dark green, with thick, overlapping scales and white patches (stomatal banding) on their undersides. [Stomata are microscopic pores on leaves and young stems that take in carbon dioxide and give off oxygen and water vapor. They are usually more numerous on the leaf undersides.] The way the foliage fans out in flattened, horizontal sprays resembles the head of a hatchet or ax, resulting in the species name, dolabrata, derived from the Latin dolabra (“pick-ax”). Thus, battle ax cedar is one of its common names. As is lizard tree – because the thick, overlapping leaf scales are thought to resemble the scales of a lizard.

Thujopsis seed cones and leaf undersides. (photo: by Krzysztof Ziarnek at Arboretum Wirty, Northern Poland, Wikimedia Commons)

The small seed cones are broadly oval to rounded, brownish, ½ to ¾ inch long, and held at the tips of branches. They consist of 6 to 8 thick, woody scales, each fertile scale containing 3-5 winged seeds.

The species dolabrata has two varieties – a central/southern variety known as var. dolabrata and a northern variety (growing in northern Honshu and southern Hokkaido) known as var. hondae (aka hondai). The latter has smaller, denser foliage and more rounded cones.

Hardy to USDA Zone 5 or 6 (minimum temperature -20 degrees F.), hiba arborvitae prefers moist, well-drained, organic soil and protection from cold, dry winds. It grows best in light shade or full sun, but tolerates considerable shade and various soil types. Native to areas with ample rainfall, it does not tolerate drought. Where rainfall is seasonal or otherwise inadequate, it requires reliable irrigation. It has no serious insect or disease problems.

With its reddish bark, deep green scale-like foliage, and impressive size, Thujopsis dolabrata resembles our iconic Pacific Northwest native conifer, western red cedar (Thuja plicata). Its foliage is clearly more distinctive – the bold, deep green patterning of the leaves, and the silvery-white mosaic that decorates their undersides – but the alleged similarity to lizard scales eludes me! Admirers with small gardens may have room for a lovely dwarf cultivar, Thujopsis dolabrata ‘Nana’, available at many retail nurseries. In ten years, it forms a low, spreading mound about four feet tall by six feet wide.

Corinne Kennedy is a Garden Guide, frequent contributor to the Seattle Japanese Garden blog, and retired garden designer.