According to fossil records ferns first appeared on earth 400 million years ago. The majority of the 12,000 living species are found in the tropics but many occur in temperate zones.
Ferns are vascular plants (they have vessels that carry liquids to the various parts of the plant) that can usually be distinguished from other plants by their large feathery leaves. Immature ferns develop as a “fiddle head” which looks like the head of a fiddle and which uncoils and spreads as it grows.
The fiddleheads of our most familiar woodlands develop underground for several years. In their final season, they multiply very rapidly, pushing their coiled tops above ground. In a few weeks of growth and uncoiling they become mature fern fronds.
Young fiddleheads, when cooked, look like asparagus and are considered a great delicacy by Maritimers. Fortunately for us they have shared their love of fiddleheads with others across the country.
The stems of ferns are not as complex as the stems of other plants, and are often reduced to a creeping underground root. Although ferns do not display any secondary growth –the type of growth that results in an increase in diameter and the formation of bark and woody parts—some ferns grow very tall. Ostrich ferns which grow along many creeks can reach six or seven feet (1.5-2.0m) tall.
The leaves, known as fronds, are often finally divided into smaller leaves called pinnae; these divided leaves spread widely and therefore collect more sunlight. It is necessary for the ferns to develop this way because they grow on the forest floor where there is dense shade.
Many ferns are almost all leaf, and even in giant tree ferns, the leaf is the main feature, the “stem” being composed of a mass of overlapping leaf bases. The leaf may be bladelike or more often they are finally divided into a regular fringe of smaller leaflets.
The spores of ferns develop on the undersides of the leaves. They are usually clustered; the clusters have a brownish colour and are often mistaken for insect eggs or patches of disease (rust). In a few ferns such as the cinnamon fern only specialized leaves bear the spore sacs, however in most ferns spores develop in all mature leaves.
Some of the spore sacs develop in distinct patterns which help identify the plant. Others are formed around the edges of the leaves. Many ferns including the Christmas fern (gets its name because it stays green all winter) have groups of spore sacs that are covered with a thin scale.
As the spores mature the outside covering dries and shrivels. When the outside ring of the sacs that contain the spores dries out it snaps open sending the powder-like spores into the air. The number of spores produced by a single leaflet may be as high as 52 million. Only a few of these germinate and produce new ferns.
Speaking of Nature
Jim Ferguson, 5313 River Road, R.R.5, Renfrew, Ontario K7V 3Z8 email jamesh@nrtco.net
Many articles from this column are now on the blog at http://www.canadian.naturally.blogspot.com
Ferns are vascular plants (they have vessels that carry liquids to the various parts of the plant) that can usually be distinguished from other plants by their large feathery leaves. Immature ferns develop as a “fiddle head” which looks like the head of a fiddle and which uncoils and spreads as it grows.
The fiddleheads of our most familiar woodlands develop underground for several years. In their final season, they multiply very rapidly, pushing their coiled tops above ground. In a few weeks of growth and uncoiling they become mature fern fronds.
Young fiddleheads, when cooked, look like asparagus and are considered a great delicacy by Maritimers. Fortunately for us they have shared their love of fiddleheads with others across the country.
The stems of ferns are not as complex as the stems of other plants, and are often reduced to a creeping underground root. Although ferns do not display any secondary growth –the type of growth that results in an increase in diameter and the formation of bark and woody parts—some ferns grow very tall. Ostrich ferns which grow along many creeks can reach six or seven feet (1.5-2.0m) tall.
The leaves, known as fronds, are often finally divided into smaller leaves called pinnae; these divided leaves spread widely and therefore collect more sunlight. It is necessary for the ferns to develop this way because they grow on the forest floor where there is dense shade.
Many ferns are almost all leaf, and even in giant tree ferns, the leaf is the main feature, the “stem” being composed of a mass of overlapping leaf bases. The leaf may be bladelike or more often they are finally divided into a regular fringe of smaller leaflets.
The spores of ferns develop on the undersides of the leaves. They are usually clustered; the clusters have a brownish colour and are often mistaken for insect eggs or patches of disease (rust). In a few ferns such as the cinnamon fern only specialized leaves bear the spore sacs, however in most ferns spores develop in all mature leaves.
Some of the spore sacs develop in distinct patterns which help identify the plant. Others are formed around the edges of the leaves. Many ferns including the Christmas fern (gets its name because it stays green all winter) have groups of spore sacs that are covered with a thin scale.
As the spores mature the outside covering dries and shrivels. When the outside ring of the sacs that contain the spores dries out it snaps open sending the powder-like spores into the air. The number of spores produced by a single leaflet may be as high as 52 million. Only a few of these germinate and produce new ferns.
Speaking of Nature
Jim Ferguson, 5313 River Road, R.R.5, Renfrew, Ontario K7V 3Z8 email jamesh@nrtco.net
Many articles from this column are now on the blog at http://www.canadian.naturally.blogspot.com
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