Difference Between Ginkgo And Cycads
The ginkgo, or maidenhair tree, is like no other. As tall and stately as an oak, it produces a thick covering of beautiful, fan-shaped leaves. These unique leaves have no midrib. Instead, the entire leaf surface is etched with parallel rows of delicately forking veins. Many of the leaves bear a distinctive top notch that divides the leathery blade into two shapely lobes. Any breeze sets the leaves aflutter, each one twirling and twisting on its long, thick stalk, or petiole. In fall, the leaves turn from gray-green to bright yellow. They cling to the tree long past those of other deciduous plants.
In overall shape, the ginkgo is tapering, with a thick, sturdy trunk. Its gray, corky bark develops many cracks and fissures with age. Like other gymnosperms, the ginkgo produces wood, or secondary growth, so its trunks and branches expand in width as well as in height.
During its first year, a ginkgo produces clusters of leaves directly from the surface of its branches. In later years, the branches produce short, thick shoots, each of which ends in a whorl of leaves. Ginkgoes grow very slowly, but can eventually reach heights of up to 100 feet (30 meters).
As in conifers and all other seed plants, the visible portion of the ginkgo—the tree—is asexual (neither male nor female). Only the tiny gametophyte generation (the pollen grains and ovules) comes in two distinct sexes. But ginkgo trees are often referred to as “male” and “female” because pollen and ovules are produced on separate individuals. The so-called “male” trees bear short, dangling pollen fronds that resemble catkins. The “females” produce pairs of ovules, or egg-producing buds. Like conifers, ginkgo trees rely on the wind for pollination. Once they are pollinated, the ginkgo’s ovules produce plumlike seeds about 1 inch (2.5 centimeters) long and wide.
The Cycads
If a giant fern married a palm tree, their offspring would look like a cycad. In fact, the ancestors of these remarkable plants were the treelike seed ferns, which disappeared along with the dinosaurs at the end of the Cretaceous period, 66 million years ago.
Characteristics
Cycads can be recognized by their circular crowns of arching fronds. Like the frond of a giant fern, each leaf consists of a long midrib with a row of smaller leaves, or pinnae, on each side. When it first emerges from the stem, the young cycad leaf is curled like the fiddlehead of a fern.
Once its large fronds have unfurled, the mature cycad looks like a palm tree, with a large, umbrella-shaped crown. The trunks of cycad trees likewise resemble those of palms. As in palms, the broken bases of the cycad’s dropped leaves form a heavy armor of thick spikes.
Cycads produce pollen cones and seed cones, often at the upper tip of their trunks. As with the ginkgo, these male and female parts occur on separate trees. Both wind and insects help carry the pollen from the “male” trees to nearby “females.” The majority of cycads stand less than 10 feet (3 meters) high. A few can reach 30 to 60 feet (9 to 18 meters) in height. Many grow primarily beneath the surface, with underground trunks that resemble gigantic turnips or carrots. Whatever their height, the trunks of most cycads remain soft and fleshy. Only a few species produce any significant amount of wood.