| age |
Devonian
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| division-name |
Pterophyta
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| evolution |
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| gametophyte |
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| habit |
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| leaves |
megaphyll. Dominate the entire plant and is a major evolutionary advantage due to high surface area:volume ratio allowing for efficient photosynthesis.
The young leaves grow from a coiled circinate vernation position that protects the developing leaf.
Leaves also serve as major players in reproduction.
At the base of the leaf is a a stipe (a supporting stalk), which attaches the leaf to the rhizome. Stipe continues through the leaf as a rachis.
Leaves often have a compound structure. Pinnate, then pinnae, then pinnules.
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| life-cycle |
Homosporous and Heterosporous
Rapidly complete their life cycles.
Eusporangiate and leptosporangiate ferns. Only ferns show examples of leptosporangium.
Perennial
From a reproductive sense, there are 3 groups of ferns:
- homosporous
- homosporous + leptosporangiate
- heterosporous + leptosporangiate
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| links |
Cool life-cycle animation
More Life-cycles
Stem anatomy
Handy quick reference
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| members |
the ferns. Extremely diverse: Tiny water ferns, epiphytes, tree ferns, etc. Characterized by their megaphylls
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| rhizome |
underground. Roots form from pericycle in the vicinity of leaf base.
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| roots |
.
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| sporangia |
In homosporous + leptosporangiate ferns, the sporangia are located on the underside of the leaf. Present usually as a compact sorus but can come in other forms such as layer at the end of a leaf. Fewer spores are produced than previous divisions.
Most ferns protect the sorus with an indusium. Some protect with a false indusium (rolled up leaf instead)
The sporangium has lip cells that are thin walled and an annulus that is sensitive to dryness which snaps (same process as elaters) and launches the spores.
Spores are green, photosynthetic and heart shaped. The archegonia form near the notch of the heart and near the rhizoids, the antheridia typically mature first.
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| stems |
Short and compressed. Lengthening of internodes not common.
Dominated by the siphonostele
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| stomata |
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| traits |
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| vascular-system |
siphonostele
Evolution of this stele accompanied the megaphyll.
In most ferns, however, the stele is broken by leaf gaps where a vascular strand departs central column to connect a leaf.
Structure of vascular tissue is (from out to in): Pericycle, pholem, xylem, phloem, pericycle.
Further modification resulted in Dictyostele. A siphonostele with overlapping leaf gaps. These leaf gaps cause the stele to break into seperate bundles that weave up the stem. Individual bundles are named meristeles.
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