Forest Preserve District of Cook County, Illinois
Nature Bulletins
Newton Home Page

Introduction and Instructions

Search Engine

Table of Contents



Ferns are Fascinating
Nature Bulletin No. 633   March 18, 1961
Forest Preserve District of Cook County
Daniel Ryan, President
Roberts Mann, Conservation Editor
David H. Thompson, Senior Naturalist

About 390 million years ago, scientists say, some small leafless and rootless plants became able to live entirely on land. During the next 60 million years, many of their descendants developed into a wide variety of specialized types described briefly in our Bulletin No. 330 -- Plants of the Coal Age. Among those new-fangled plants were various types of ferns.

They were the first plants to have true roots, stems and leaves with a system of channels, even though quite primitive, for conducting mineral-laden water from the soil to the leaves; and food, manufactured in the chlorophyll-bearing cells of the leaves, to all parts of the plant.

The true ferns and the tree ferns dominated the landscape for the next 175 million years Those we see today in the United States are the smaller, hardier forms that managed to survive violent disturbances of the earth's crust and drastic changes in its climates. They retain many of the primitive features of their ancestors: they do not have flowers, followed by seeds. Flowering plants, which bear seeds protected by a fruit or shell, did not appear until the Cretaceous Period, less than 95 million years ago.

Ferns reproduce by means of spores that are contained in tiny sacs called sporangia On many kinds of ferns, groups of these sporangia appear as brown dots on the under side of the fronds (leaves); on others they form clusters in berry-like masses on separate stalks. Each sac is filled with hundreds of microscopic spores that resemble dust. When the spores are ripe, the sac opens and those that fall or are borne by wind to shaded, damp soil develop into flat, heart-shaped, green organisms -- about 1/10th the size of a dime -- each called a prothallium. On the under surface of it are male and female organs that produce sperm and "egg" cells If water is present -- dew will do -- the sperm swims to an egg and enters it. From this union the leafy fern plant develops.

Most of the true ferns are thin in texture and thrive best in moist shady places. Of several thousand species in the world, by far the greatest number occur in tropical rain forests. They attain greatest size and luxuriance in Brazil, Ceylon and New Zealand. Some of the tree ferns become 30 or 40 feet tall, with fronds 15 feet in length.

In our country, most kinds occur in deep moist woodlands, ravines, rock gorges, and on ledges near waterfalls. The scarcity of suitable habitat explains why only 36 species and subspecies have been recorded in the Chicago region Thanks to "progress" and plundering people, several of those have become extinct.

Some kinds, however, are adapted to live in drier or even arid conditions Among those found in old fields, open woodlands, or along roadsides, the Lady Fern is common in Cook county. Chiefly in open woodlands, we have the Brake Fern or Bracken. Of all ferns, it is most widely distributed over the earth and one of the few used by man for food, medicines, bedding, etc.

In your forest preserves the Maidenhair Fern and the unique Walking Fern can be found. Among the more fernlike kinds, the Fragile Fern is the smallest and the Ostrich Fern is perhaps the finest. In, or at the edges of marshes we have the Sensitive Fern, Royal Fern and, largest of all, the Cinnamon Fern.

Ferns are fascinating. You usually find them in fascinating places -- far from beaten paths. But when you do, please remember and obey our wildflower slogan: "Love 'em and leave 'em, so that others may enjoy them".

To return to the Nature Bulletins Click Here!
Hosted by NEWTON

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Sponsered by Argonne National Labs