Japanese katsura tree an exception to ‘native’ rule

Those who have known me over the years can remember my enthusiasm for exotic trees and shrubs, non-natives such as the Amur maackia or any number of Oriental maples. In recent years, however, I have evolved into a native plant purist, spurred in that direction by concern for the threat to natural areas from invasive species. Now I cringe when I think of the days I praised the merits of Japanese barberry and burning bush.

Yet there is still one non-native tree that I cannot seem to abandon, particularly in autumn, and that is the katsura tree (Cercidiphyllum japonicum), a colorful and distinctive shade tree native to Japan. I planted one for Marjorie in her garden two years ago, rescuing it from a crowded row of tall but spindly trees in a research plot at the university, leftovers from someone’s forgotten project. Its root system was minimal and we were doubtful about its future. We kept the hose nearby for that first summer and said more than one prayer for its survival. Something worked, for this year it added 2 feet of growth in all directions and we began to shape its future with the pruners.

We love this tree for its foliage, heart-shaped leaves similar to those of the redbud. (The genus name, Cercidiphyllum, translates to “leaves like Cercis, the redbud”.) Robert Frost could have been thinking of the early spring leaves of this tree when he penned “Natures first green is gold.” The evening sun shining through the unfolding bronze leaves will bring his verse to mind.

As spring progresses, the leaves mature, turning dark green above and blue-green below. In fall, the color changes again to clear yellow touched with scarlet. In some trees I have seen the fall color approach apricot.

Katsura tree is also striking in winter. Its form varies from pyramidal to broad spreading, but always interesting against the winter sky, and the somewhat shaggy bark of older trees contributes a unique textural quality to snowy winter landscapes. The branches have a softly arching character. This quality is often enhanced by a multitrunk habit, although single-trunk trees can be found as well.

The largest tree in China, katsura tree may be too big for many modern landscapes. I remember photographing one old street tree in Amherst, Mass., planted in 1877, that in 1983 measured 70 feet high and 20 feet wide.

For smaller gardens, the cultivar Pendula may be a better choice. It is a small, gracefully weeping form growing slowly to 25 feet in height. While popular in the United States only since its introduction around 1966, Pendula has been grown in Japan for more than 300 years.

In autumn I keep a keen eye on the golden leaves of katsura, waiting for the moment when the leaves release their hold on the tree’s branches and fall to the ground. For in that moment, particularly if it coincides with a warm sunny afternoon, the senescing leaves release a strong, spicy fragrance – burnt sugar, ripe apples, and strawberries – as the slender petioles slip their hold. In that smell are all the reasons why I love being a gardener.

Send queries to Gardening Questions, P.O. Box 418, Ellsworth 04605. Include name, address and telephone number.