In Bloom: Japanese Spicebush Brings Brilliant Yellow Color to the Seattle Japanese Garden
By Corinne Kennedy
Japanese spicebush (Lindera obtusiloba) is a large deciduous shrub that’s highly attractive now in late winter and again in autumn. In both seasons, it brings warm yellow color to the Seattle Japanese Garden – with delicate, bright yellow March flowers, and months later with glowing butter-yellow fall color. The yellow coloration of its flowers resembles that of several other early-blooming woody plants in our garden. These shrubs and small trees include winter hazel (Corylopsis, featured in a March 2016 post), Cornelian cherry (Cornus mas, worthy of a future post), and Forsythia ovata, a deciduous shrub familiar even to non-gardeners.
Japanese spicebush belongs to the ancient family Lauraceae, which includes many deciduous and evergreen genera (plural of genus, the first word of a scientific name; species is the second word). Most are characterized by foliage and stems with high concentrations of essential oils. One of these is bay laurel (Laurus nobilis), which gives us the bay leaves used in cooking.
The genus Lindera is also ancient, as shown by the fossil record of one species, Lindera rottensis, dating from at least 20 million years ago. It’s estimated that Lindera includes 80-100 species, most of them little-known in Europe and the United States. Three species, however, are native to North America, including Lindera benzoin, known simply as spicebush. It grows in states east of the Mississippi River and in eastern Canada.
Many more Lindera species, mostly understory plants, are native to eastern Asia. Among them are the two Japanese species planted in Area Z of our Seattle Japanese Garden, Lindera obtusiloba (2 plants) and Lindera praecox (one plant). The former grows on hills and in the mountains of Japan, except on the northern island of Hokkaido – and is also native to China and Korea. Its species name is obtusiloba, which means “blunt-lobed,” and refers to the rounded edges of its leaves. The large leaves, however, are quite variable in shape. Some are unlobed (entire), some three-lobed, and others two-lobed -- resembling a mitten. The common name, Japanese spicebush, refers to the spicy scent of their leaves and twigs. Many other Lindera species also have the word spicebush included in their common names.
Lindera obtusiloba is a multi-stemmed large shrub, sometimes considered a small tree, that matures at about 20 feet tall. With time, it develops a wide-spreading, vase-shaped habit. Young branches are a smooth yellow-green, maturing to black-brown or gray.
In late winter or early spring, short clusters of bright yellow, star-shaped flowers open on bare stems, before the leaves unfold. Plants are dioecious – that is, either male or female. The male flowers resemble the female flowers, but they’re larger and showier in appearance. When both sexes are present, female plants produce ¼-inch round red fruits, known as drupes, that mature to a shiny black and persist into autumn.
The large leaves of Japanese spicebush are approximately 4 to 6 inches long, and emerge bright green, often with attractive purple tints. They mature to a lustrous dark green, paler on the leaf undersides. Finally, “autumn transforms the plant into a glowing, golden yellow beacon” [www.greatplantpicks.org]. It was given Britain’s Award of Merit in 1952 in recognition of this beautiful fall display. Afterwards, it was discovered that the species given this award had been mis-identified. England’s famous Hillier Nurseries later acknowledged their error: they had distributed the plant as Lindera triloba – not as Lindera obtusiloba, its correct scientific name.
Native to woodlands, Japanese spicebush grows best in bright or open shade, but tolerates full sun in the Pacific Northwest. Unlike most shrubs, it develops striking fall color even in shade, so gardeners here are encouraged to plant it in shade or part shade, where its bright fall color will be most appreciated.
Lindera obtusiloba prefers fertile, moist, well-drained, acid soil, and is hardy to at least USDA Zone 6 (minimum temperature, -10 to 0 degrees F.). It adapts well both to cold winters and hot summers. It does best with regular watering, but in our area tolerates occasional dry periods – as well as seasonal wetness, if drainage is adequate. The characteristic spicebush scent is not as pronounced as in other Lindera species. Insect and disease-resistant, it is appreciated for its ease of cultivation.
Seeds and leaves were used traditionally to produce oil and as a tea substitute (replacing the leaves of Camellia). In addition, young leaves were fried to create a dish used in Buddhist ceremonies. Contemporary studies indicate that plant extracts may have medicinal uses in the treatment of allergies and depression.
As mentioned above, our Seattle Japanese Garden contains a second Japanese species, Lindera praecox (previous scientific names: Parabenzoin praecox and Benzoin praecox). Most authorities record only the non-specific common name of “spicebush.” When compared to Lindera obtusiloba, it has smaller, unlobed leaves that don’t develop glowing yellow fall color. In addition, its flowers are a paler greenish-yellow and its ripe fruits brownish-yellow or reddish-brown – not the deeper colors of Japanese spicebush. Both species were first introduced to the West in 1880, but L. praecox appears to be less available to American gardeners – perhaps only from nurseries in the UK. Lindera obtusiloba, on the other hand, is available in the U.S. from specialty and mail-order nurseries.
Uncommon in the Pacific Northwest, Japanese spicebush is an elegant large shrub that deserves to be more widely planted. I’m looking forward not only to the bright yellow color of its delicate March flowers, but also to the “golden-yellow beacon” of its autumn foliage.
Corinne Kennedy is a Garden Guide, frequent contributor to the Seattle Japanese Garden blog, and retired garden designer.