Difference Between Horsetail And Club Mosses
More than any other group of plants, the horsetails deserve the name “living fossils.” In modern times, they number just 15 species, all of which belong to a single genus—Equisetum—that has survived virtually unchanged for 300 million years. Equisetum may hold the distinction of being the oldest living plant genus on Earth.
The first shoot to appear is deep green, with spirals of feathery branches growing out from each joint of the stem. These are the vegetative shoots. Typically, they appear in early spring, then give way to a very different type of fertile, or spore-producing, shoot.
The spore-producing shoots resemble flesh-colored asparagus sprouts. Their joints give rise to whorls of tiny brown leaves that resemble pointy crowns encircling the stem. The tip of each fertile shoot bears a conelike structure, called a strobilus, which produces spores. Both types of shoots stand between 1 and 4 feet (between 30 and 120 centimeters) high.
The horsetail’s branching green stems reminded early Europeans of a horse’s tail, earning the plant its common name. American pioneers called them “scouring rushes” for their usefulness in scrubbing out pots and pans. The plant’s abrasiveness comes from the glassy mineral silica, which is very abundant in its epidermis, or surface cells.
The most common of the creeping club mosses is the running pine, or stag’s-horn moss (Lycopodium clavatum). Its ground stems grow up to 10 feet (3 meters) long. From these stems grow upright spikes, each crowned with three strobili. The stems are covered with deep-green, scalelike leaves.
The club moss known as ground cedar (L. complanatum) is native to Canada and the northern states. It produces fanlike branches that resemble sprigs of juniper with needlelike leaves. Fir club moss (L. selago) forms long underground stems (rhizomes) that give rise to upright shoots some 10 inches (25 centimeters) tall. It grows in northern forests, high mountains, and cool, wet woodlands and bogs. The yellowish-gray Alpine club moss (L. alpinum) is one of the hardiest plants on Earth, capable of growing under the ice and snow of high mountain peaks and the Arctic tundra.
The name “club moss” is also used to refer to many species that belong in a separate but closely related group, the 700 species of spike mosses (family Selaginellacea). Like true club mosses, spike mosses are small, creeping evergreen plants, with long, thin stems bearing many tiny leaves. Some resemble ferns, with fans of tiny leaflets on long, delicate fronds. Still others form climbing vines, or trail from the branches of trees. In general, their leaves tend to be shiny and deeply colored, with hues ranging from dark green to peacock blue.