There are some trees whose showiness does not end once they’ve lost their leaves in autumn. Some trees have an attractive bony framework that is then revealed. Ginkgo tree, for instance.
Leafless, a ginkgo (Ginkgo biloba) tree, soft and green in summer, appears as if each main limb knows where it is going, jutting boldly and alone into space to give the whole tree a coarse yet pleasant appearance. Instead of twigs, a ginkgo’s stout main branches are dotted with many short, stubby shoots, each an inch or so in length and elongating less than that amount each season.
UNIQUE LEAF FORM
If you come upon a ginkgo that has recently shed its leaves, make sure to look down at the ground. This tree’s leaves tend to drop early, and all at once. But it’s a crime to rake them. They are pure yellow in color, appearing as if a patch of sunlight is shining on the ground. The leaves have the shape of a Japanese fan, much like those of another plant, maidenhair fern. Hence, ginkgo’s other common name — “maidenhair tree.”
Closer inspection of the leaves reveals something odd. The veins of a ginkgo’s leaf run more or less parallel; that is, the veins emanate from a common point at the base of the leaf, then splay outwards towards the tip of the leaf, just like the spines on a fan. Such venation is not characteristic of other broad-leaved plants.
Look at a maple leaf for contrast, and you will see there are main veins, sub-veins, sub-sub-veins, and so on, running in all directions on the leaf. The parallel venation of ginkgo leaves is characteristic of either monocotyledonous plants, such as grasses (to which the ginkgo obviously is not related), or gymnosperms, such as conifers.
Ginkgo is, in fact, a gymnosperm, one of the few broad-leaved gymnosperms. At one time — 200 million years ago, in the Paleozoic and Mesozoic eras — such plants were common. Ginkgo is the sole survivor of this evolutionary line of plants, and, along with cycads, is the most primitive of seed plants.
A SOFT APPEARANCE, A TOUGH DISPOSITION
North America and Asia were home to ginkgos many millions of years ago, but in recent geological time, ginkgos disappeared from North America. Even in Asia, truly wild ginkgos were once thought to no longer exist, though cultivated specimens have graced courtyards of Buddhist temples in China and Japan for the past thousand years.
In treks through China’s interior during the early part of this century, Frank Meyer, a plant explorer for the U.S. Department of Agriculture, finally came upon wild ginkgos.
The first ginkgo tree in North America was planted in a Philadelphia garden in 1784, and now some of the most beautiful ginkgo plantings are rows of these trees lining city streets. The delicate leaves of ginkgo mollify the concrete of a city. Touch the leaves in summer; they feel as soft as they look.
Gingko trees are either male or female, and it’s important to know the sex of the tree or trees before planting them. Female trees bear seeds enclosed in a fleshy covering. Problem is that the fleshy covering of the dropped fruits smell like vomit! Avoid this aroma by planting only male trees, which do not fruit, or ensuring, if planting any female trees, that no male trees are nearby.
(The fruit eventually rots away, at which time gingko nuts can be gathered and eaten. They are especially popular in Asia.)
Ginkgo is much like another survivor from prehistoric times, the cockroach, in its ability to stand up to adversity. Its leaves, though delicate in appearance, are able to tolerate polluted air. Insects or diseases are rarely a problem. The tree’s thick bark is resistant to fire, and its roots will tolerate a degree of soil acidity or salinity that would make many other plants wither. The roots run deep enough to resist wind and snow damage.
Ginkgos are frequently planted as city trees, oblivious to fumes spewed out by passing cars and other affronts.
Who could have suspected such a fate for a tree whose leaves once rustled at the swish of a dinosaur’s tail?
Lee Reich writes regularly about gardening for The Associated Press. He has authored a number of books, including “Growing Figs in Cold Climates” and “The Pruning Book.” He blogs at http://www.leereich.com/blog. He can be reached at firstname.lastname@example.org.