The California redwood forest has an ecosystem like none other on earth. The stately redwood trees (Sequoia sempervirens) tower above more delicate woodland plants. Among them are a number of vigorous ferns that dot the landscape in large groves. By taking a closer look you will see that each fern has unique characteristics that will help you to identify them.
Determine the Habitat
An important tool when identifying any type of plant is a good botanical field guide. A good native guide will describe habitat as well as plant characteristics. Good, clear color pictures are equally as important.
Within any forested area there will be microclimates. Many ferns need ample water and will be near a water source. In the redwood forest in California there are several moisture-loving ferns. At the top of this list are the maidenhair ferns. They are delicate and the rounded fronds are held on black stems. The two species found there are five-finger fern (Adiatum pedatum), and common maidenhair fern (Adiatum capillus-veneris). The California polypody (Polypodium californicum) is another moisture-loving fern found along the banks of streams. Others are dry-land ferns and can be found in open clearings.
Some ferns can even tolerate full sun. One of these is the taller bracken fern (Pteridium aquilinium), and a smaller one, the golden-back fern (Pityrogramma triangularis). The lady fern (athyrium felix-femina) is also a moisture lover but can be found a little further away from a water source as long as it receives afternoon shade.
Similar to lady fern, but featuring 6- to 9-foot fronds, is the giant chain fern (Woodwardia fibriata). All of the above ferns are deciduous. The common evergreen Western sword fern (Polystichum munitum), can withstand all of the micro-climates found in the redwood forest. Its leathery, deep green fronds set it apart. In its juvenile state the licorice fern (Polypodium glycyrrhiza), looks similar to the sword fern. It will remain smaller, though, and grows on trees and stumps. The California wood fern (Dryopteris arguta) has thick glossy evergreen fronds, and is found in moist shade.
The way to narrow down the search is through the process of elimination. Even ferns that are very similar will have some characteristics specific to that fern.
The new spring growth of ferns are called fiddleheads. Learning to recognize how each frond looks before it opens is helpful. Some fiddleheads unfurl in a bright, delicate tone of green, while others have brown hairs, or brown coloration. Fern size will also coincide with the size of the fiddleheads.
In summer the full size of the plant will be apparent. The leaflets found on each frond have variations too. Some ferns have flat leaflets, while others will be turned under or ruffled. Early fronds can be deceiving, but mature fronds reveal whether they are delicate, or thick and leathery. The individual leaflets may be smooth or finely cut.
Fall and Winter Tips
If you can determine whether a fern is deciduous or evergreen you can scale down your search considerably. In the fall it is easy to see which ferns are turning brown and going into dormancy, and which are still very green. If the spores are intact on the underside of the leaflets, they may also yield clues. A good field guide will describe the pattern, size and color of the spores for each species.
Winter is the dormant period for ferns. The only clues available at this time of year are the fronds (generally evergreen).
Some ferns spread by underground roots or rhizomes. An example of this is the bracken fern. It sends out underground runners that can appear a distance from the plant. Other ferns such as the Western sword fern grow in large patches but are spread by spores rather than roots. By studying the growth pattern you can learn to recognize ferns in many stages or maturity.