Pellaea atropurpurea
| Purple-stem cliffbrake | |
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| Formation of Pellaea atropurpurea | |
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| Species: | P. atropurpurea
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| Pellaea atropurpurea L. Link | |
This is a fern, P. atropurpurea, commonly known as purple-stem cliffbrake or just purple cliffbrake. Brake is an old word for fern, related to the word bracken. Like many other members of the Pteridaceae, it is a rock plant, needing a calcareous substrate.
P. atropurpurea is an apogamous autotriploid, with 3n=87 (actual base number, n=29), and is one of the historical parents of the hybrid species complex, Pellaea glabella. Apogamy, or the ability to reproduce non-sexually, is common among rock ferns in the Pteridaceae.
This cliffbrake can be grown in a rock garden or potted with care.
Characteristics
This fern produces clumps of widely arching fronds. The stipe and rachis of the blade are purple, while the blade itself has a blue-gray tinge to it. The upper pinnae are long, narrow, and undivided, while the lower ones are divided into 3-15 pinnules. The pinnae are, for the most part, opposite. Fertile fronds are longer and more heavily divided. They produce sori, which lack a true indusium, within the inrolled margins of the pinnae.
This plant may be distinguished from the similar Pellaea glabella by its hairier nature and larger form.
Ecology
Pellaea atropurpurea grows in the crevices of dry limestone cliffs, rocky slopes, and mortared walls. It is endangered in Florida, Iowa, and Rhode Island.
References
- USDA Plants Database: P. atropurpurea
- P. atropurpurea in Flora of North America
- Boughton C. 2005. Ferns of Northeastern and Central North America. New York: Houghton Mifflin. 417p.
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