Nancy Martin, age 72, of Manheim, Pa., for her question:
WHAT ARE AIR FERNS?
Ferns come in many shapes and sizes. Some have such tiny leaves that they almost look like moss, while others are so huge that they are as tall as some trees. Ferns 40 feet tall can be found in the Pacific Islands and South America. They have thick, woody trunks and feathery crowns of massive leaves. Tree ferns are common in the damp mountainous regions in the tropics.
Ferns can be found almost anywhere in the world, from the hot tropics to the cold Arctic Circle in the north. You'll find them growing among rocks and cliffs or in shady, moist woods. They live in coastal regions and in spots that are over 15,000 feet high.
More than 10,000 different kinds of ferns can be found on earth. About 300 of the varieties can be found growing in North America.
One of the more interesting types is called an air fern. It can be found in tropical locations and has long stems that creep upward on tree trunks. The ferns live high above the ground.
Called epiphytes, air ferns get their nourishment from the moist air and from the decayed matter which collects on the bark of the trees. They are indeed very interesting plants.
Leaves of ferns are called fronds. They are large when compared to the plant's stem and come in many forms. Some are heart shaped while others are like long straps. The leaves usually develop in coils and are often covered with brown scales.
Ferns reproduce by means of spores and sex cells. Small cases contain the spores and they grow grouped in dots or lines on the backs or sides of the leaves. When they ripen, the cases burst open and the spores fall to the ground. Each one can develop into a tiny green plant that is shaped like a heart. The tiny plant develops special tissues which produce both female and male cells. The male cell comes from an organ called the antheridium, which can be compared to the anther in flowers, although the fern is flowerless. The female organ of the fern is called the archegonium.
When the sex cells become mature, the male cell swims through the moisture on the plant to the female cell and fertilizes it. Then the egg grows into the mature fern plant.
Botanists call the reproduction process of the fern the alternation of generations. The two generations are the large fern which produces the spores, and the tiny fern plant which produces the sex cells.
Ferns are favorite plants with many gardeners. Many types grow nicely indoors and help to make our homes more beautiful. Others add glamor to the shady spots of our gardens.