Ferns and Lycophytes: an Introduction

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marginal wood fern
Dryopteris marginalis

 

This summer I took an Audubon Naturalist Society class on ferns and lycophytes.  You’re probably wondering, “what is a lycophyte?”  Hang tight, I’ll get to that.

Apparently I’m not the only wildflower enthusiast to keep a log or life list of finds; turns out I’m also not the only one who includes ferns on that list, though ferns aren’t even flowering plants.

So what does that mean, “ferns aren’t even flowering plants”?

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that kind of looks like a flower spike, but it isn’t; it’s the fertile (spore-bearing) stalk of a rattlesnake fern, Botrypus virginianus

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If you recall from grade school science, the taxonomic hierarchy starts with the plant and animal kingdoms, then moves down to division (phylum for animals), class, order, family, genus, and finally species.

Flowering plants are in the class Magnoliopsida.  They are vascular (containing tissues that transport fluids and nutrients), and reproduce via seeds.  Ferns are in a different class: Polypodiopsida.  They are also vascular plants, but they reproduce via spores.  Lycophtyes are in a third class, Lycopodiopsida; like ferns, they are vascular and reproduce via spores, but the morphology is different: ferns consist of rhizomes with roots below and fronds above, while lycophytes have stems with roots and tiny, scale-like leaves (called microphylls) that cover the stem above ground.

Ferns and lycophytes have differing evolutionary lineages as well, but I’ll spare you the details.

The current state of taxonomy is way different from what we learned in grade school. It gets complicated because there are different systems and the scientific community doesn’t seem to be in agreement about which one best fits our current understanding of evolutionary history.  For anyone who’s interested, here’s a little detour.

One widely used system (Woese) starts with domain, of which there are three; kingdoms are the next step down.  The differentiation is rather technical, but the domains are named Archaea, Bacteria, and Eukaryota.  The plant kingdom (Plantae) is in the last of these.

ITIS (the Integrated Taxonomic Information System, one of the more authoritative sources) has adopted a seven-kingdom system as its standard. The kingdoms are  Bacteria, Protozoa, Plantae, Fungi, Animalia, Chromista, and Archaea.

A google search on the phrase “kingdoms of life” will show other systems, dividing life into five or six kingdoms.

In ITIS, the next levels below kingdom are more divided than in the old KDCOFGS system.  If you go down the tree looking for ferns and lycophytes , you’ll see below the plant kingdom two subkingdoms; the one containing ferns is divided into two infrakingdoms; one of those is composed of two superdivisions; then after that come the divisions, of which there are eight.  Ferns and lycophytes are in the Tracheophyta (vascular plants).

Ignoring the three subdivisions, there are seven classes within the division Tracheophyta:

Cycadopsida: cycads (seed plants that vaguely resemble palms)
Ginkgoopsida: ginko (Gingko biloba, all by itself way up here in the taxonomic hierarchy!)
Gnetopsida: three genera of woody plants resembling conifers
Pinopsida: conifers (non-flowering, seed-bearing plants)
Magnoliopsida: flowering, seed-bearing plants
Lycopodiopsida: clubmosses, firmosses, spikemosses, quillworts
Polypodiopsida: ferns

Older field guides and text books refer to certain plants as “fern allies” or “fern relatives”.  These include the clubmosses, firmosses, ground cedars, horsetails, scouring rushes, quillworts, and a few others.  Of those, horsetails and whisk ferns are now considered to be true ferns.  The rest are considered lycophytes.  All of this reclassification is quite recent and based on molecular phylogenetic studies.

The point I’m trying to make, other than taxonomy is messed-up but fascinating, is that ferns and lycophtyes are only distantly related to the flowering plants I usually write about.  But they are abundant, beautiful, and interesting, so I’ll be posting about them.

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a lycophyte, commonly called “ground pine”, generally known as a “clubmoss”, but it isn’t in the same class as pines, and isn’t in the same division as mosses!

 

 

Next time, a look at fern morphology and nomenclature.

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