Swamp Fern has a New Name

Fern, Oslo Riverfront Conservation Area

The first plant that Sam Chancellor (Class of 2010) mentioned in his wonderful presentation, A Gentle Introduction to Plant Names, on Saturday, November 4 for a group of twelve veteran volunteers was swamp fern, Blechnum serrulatum, pronounced BLECK-num ser-you-LAY-tum (or see-roo-LAH-tum). Sam also mentioned that scientific plant names sometimes change …

Well, what do you know? Blechnum serrulatum is now called Telmatoblechnum serrulatum. Sigh! I was surprised to find out when I looked up this fern by its old scientific name on the Florida Plant Atlas, a comprehensive and up-to-date website of Florida plants and their ranges maintained by Dr. Richard Wunderlin from the University of South Florida. Dr. Wunderlin has another common name for this plant, toothed midsorus fern — in addition to swamp fern.

Swamp fern is one of the most widespread ferns in central and south Florida. It is present at the Oslo Riverfront Conservation Area  (ORCA) on both sides of Oslo Road. In shade in moist hammock areas its fronds can be more than four feet long …

with well-spaced leaflets …

By contrast, its growth is far more compact and stout in full sun, as seen in the photo below taken on the south side of at the Oslo Riverfront Conservation Area where on a group walk on the afternoon of Sunday, October 28 …

Swamp fern, when fertile, is easy to identify …

Bob Stolze, former Curator of Ferns at the Illinois Natural History Museum, wrote up descriptions of all of the ferns that he saw at ORCA. For swamp fern, he wrote: “Spore cases (sporangia) are borne in continuous parallel lines on either side of the midrib of fertile leaflets (pinnae).

Do not be fooled! New fronds are reddened …

When not fertile, look for the finely toothed leaflets and for a single apical leaflet …

Whatever you call it, this sturdy tropical fern performs well in shade or sun as long as sufficient moisture is present.