Appalachian rockcap fern facts for kids
Quick facts for kids Appalachian rockcap fern |
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| Polypodium appalachianum | |
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Polypodium (plant)
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| Species: |
appalachianum
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The Appalachian rockcap fern (Polypodium appalachianum) is a type of fern found in eastern North America. It's also known as the Appalachian polypody. This fern looks a lot like another fern called the rock polypody (Polypodium virginianum). For a long time, scientists thought these two ferns were the same or just different types of the same plant.
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About the Appalachian Rockcap Fern
Discovering New Fern Species
For many years, scientists studied Polypodium virginianum. They noticed that even though they looked similar, some of these ferns had different numbers of chromosomes. Chromosomes are like tiny instruction books inside cells that tell a plant how to grow. Scientists found ferns with two sets of chromosomes (called diploid), three sets (triploid), and four sets (tetraploid).
The ferns with three sets of chromosomes couldn't make healthy spores. This suggested they might be a mix, or hybrid, of the two-set and four-set ferns. In 1991, scientists figured out that the original P. virginianum was actually the four-set type. They also learned that it was a hybrid itself, made from two different parent ferns.
One of these parent ferns was the two-set type, which they then named P. appalachianum. The other parent was found to be Polypodium sibiricum. Interestingly, the hybrid P. virginianum can handle warmer weather better than either of its parent plants.
How to Tell Them Apart
Even though P. appalachianum and P. virginianum look similar, there are small differences that can help you tell them apart. Here's a simple way to compare them:
| Feature | P. appalachianum | P. virginianum |
|---|---|---|
| Frond shape | Widest near the bottom | Widest in the middle |
| Pinnule shape | Narrower, more pointed | Broader, more rounded |
| Basal pinnule notch | Has a notch (a small cut) at the base | Does not have a notch |
Polypodium sibiricum, one of the parents of P. virginianum, is also a parent of another fern called Polypodium vulgare. The other parent of P. vulgare is the Polypodium glycyrrhiza.
Where This Fern Grows
The Appalachian rockcap fern (P. appalachianum) is an epipetric plant. This means it prefers to grow on rocks, especially sandstone or other hard, non-calcium rocks. However, in places like the Smoky Mountains, it can also grow as an epiphyte. An epiphyte is a plant that grows on another plant, like a tree, but doesn't harm it.
Throughout most of its natural home, you'll find P. appalachianum growing in spots that are more protected from direct sunlight and heat compared to where P. virginianum grows. Both of these fern species, and their hybrid, can form large groups of plants that are all genetically identical. These groups create dense mats that help hold organic material, like dead leaves, in place on rock surfaces.
