Dogwood

BARBARA TUFTY

May 13, 1993|By BARBARA TUFTY

WASHINGTON — Washington.--Another spring, and we still can see dogwoods flowering in our hardwood forests. Through the vistas of newly leafing oaks and maples, the horizontal sprays of gleaming white dogwood blossoms spread like flurries of snow. The four white ''petals'' we see are really not petals but bracts that grow out from the base of each tight cluster of small greenish flowers.

We've been hearing that these lovely trees, the native American dogwood, Cornus Florida, are dying, victims of the fungus anthracnose that has been spreading south from New England since the mid-1970s.

No one wants to hear about the death of the dogwood. Its graceful branches are as much a part of returning spring as warm air and bright sunlight and the singing of migrating songbirds. In the early morning sun, the sprays of blossoms catch and hold the light, shining between the young chartreuse leaves of oak.

Dogwood buds have a growth pattern that starts out in perfect symmetry. The new buds grow in twos, on opposite sides of a twig. The next pair grow exactly at right angles to the first pair. The third pair grows precisely at another right angle, and is positioned just above the first pair. And so the pattern continues. These buds are the origin of all leaves, twigs, branches, limbs -- so theoretically the perfect pattern of the dogwood would be a trunk with smaller and smaller appendages at rigid right angles to one another.

At least that's the basic plan. But now comes the disruption of chaos in nature. Each growing bud and twig becomes distorted by wind, insets, shade, animals -- a multitude of forces and accidents that quickly destroy the even symmetry and turn the tree into a turmoil of crooked branches turning every which way. In spring, the new buds rectify this disarray and form another pattern. As the buds develop into flowers, they turn and twist toward the light, forming an extended mosaic so that each flower and later leaf is held away from its neighbor and grows into an empty space to find the sunlight.

Stand beneath a branch of dogwood and look up -- almost each flower has positioned itself so that does not overlap a flower below nor is it overshadowed by a flower above. This is the pure beauty of a basic pattern of nature, shattered into chaos but then reforming another pattern to serve the need of the tree.

The fatal anthracnose fungus usually begins on the lower branches of the dogwood, causing leaves to wither brown between leaf veins or on the edges, or become disfigured with purple-rimmed spots. The disease then spreads to twigs and trunks, causing cankers and eventually killing the tree.

Large numbers of the woodland dogwoods have died in recent years. Trees growing in dense shade are hardest hit, most particularly near creeks and streams, at higher, cooler elevations, and on slopes facing north. The fungus has spread as far south as Georgia and Alabama and as far west as Tennessee and Kentucky. Following the cool forests of the Appalachian mountains, it has almost invaded the lowlands, affecting single specimens in home gardens. In backyards, the disease has spread more slowly on trees that have been planted more open to warm sunlight and circulating air.

Botanists and horticulturists have predicted a bleak future for the Cornus Florida, for as yet no known antidote has been found to save it. The fungus has the potential to annihilate the species. But a small number of native dogwoods resisting the disease have been found in areas of New York state and in Maryland's Catoctin Mountains. Also the Asian dogwood, Cornus Kouse, appears to resist the fungus, and hybrid crosses are being bred. But they are not the same. They are another variety, not our native species.

As twilight filters through the woodlands, the dogwood blossoms grow whiter in intensity, releasing the light they have been gathering and holding all day. And as dusk falls, the whiteness continues to radiate into the growing darkness.

Spring will never be the same without our native dogwoods.

Barbara Tufty is a conservation writer and editor.

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