Woodland Forest: Ferns   Leave a comment

Woodland Forest



Here in the woodland forest, several species of fern often dominate the landscape. The Cinnamon, Royal, Sensitive, and Marsh ferns, described below, are the most common.




 Division Polypodiophyta


Osmundaceae (Flowering Fern Family)




Osmunda cinnemomea (Cinnamon Fern)






The light green, deciduous Cinnamon Fern can reach a height of about 1.5 meters. Sterile, pinnate Fronds (Fern leaves) arise from a circular base and flare outward. Cinnamon colored fertile leaves (Spore Stalks) bear spores along most of their length. Ferns reproduce asexually from rhizomes (Underground Stems) and sexually from spores. Young sterile fronds can be eaten raw or cooked. Preparations made from fern roots have been used externally to treat rheumatism and internally to treat colds, headaches, etc.



Osmunda regalis (Royal Fern)








The light green, deciduous royal fern can reach a height of about 1.5 meters. Sterile, bi-pinnate fronds (Fern Leaves) arise from a circular clump. On each leaf there are 7-9 pairs of pinnae each of which has 7-13 pairs of pinnules. Dark Green colored fertile leaves (Spore Stalks) bear spores at the end of the leaf. After spores are released, the leaves turn to a brownish color. Leaves and roots arise asexually from underground stems (Rhizomes). Young sterile fronds either can be eaten raw or cooked. Their taste has been compared to asparagus.



Dryopteridaceae (Wood Fern Family)


Onoclea sensibilis (Sensitive Fern)





 The light green, deciduous sensitive fern is relatively short (about 0.6 meters high). The sterile leaves (Fronds) bear pinnae with wavy margins. The spores are formed on the upper part of a brown fertile frond. Young unfurled leaves can be eaten raw or steamed. The root is also edible but should be cooked.



Thelypteridaceae (Marsh Fern Family)


Thelypteris palustris (Marsh Fern)






Leaves (Fronds) bear pinnae (leaflets) that have branched veins that extend from the middle vein to the outer margin. The fronds tend to be twisted as shown below. Spores are formed on the undersides of upper pinnae. The young, unfurled leaves are edible.



Adaptations of ferns in general:

 1. Ability to maximize light absorption. The fern frond (Leaf), pictured above, is generally divided into numerous pairs of pinnules, providing a large, exposed surface area that allows maximum light absorption, an advantage in the shaded forest environment. Light provides the energy to fuel photosynthesis, the process that manufactures organic molecules such as sugar that in turn provide the energy to fuel plant metabolism. Why is photosynthesis important to our well being?

2. Oxygen Availability. Many fern species grow in oxygen poor, water soaked environments. In some of them, the upper roots lie on or above the surface, allowing oxygen exchange with the atmosphere rather than from lower oxygen depleted, standing, water. Why is oxygen important to the well being of a plant?

 3. Increased numbers of offspring. An enormous number of haploid spores are produced by the visible fern (Sporophyte). Each spore may have the opportunity to develop into a microscopic gamete (sex cell) producing gametophyte. The union of a male and a female gamete produces a diploid sporophyte that we identify as a fern. The large number of spores and gametes helps ensure continuation of the species. Is there an advantage to having a large sporophyte and a microscopic gametophyte generation?




Posted February 4, 2011 by zottoli

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