Everything about Lycopodiophyta totally explained
Silurian to recent
| image = Lycopodium_plant.jpg
| image_caption =
Lycopodiella cernua
| image_width = 250px
| regnum =
Plantae
| divisio =
Lycopodiophyta
| subdivision_ranks =
Classes
| subdivision =
Lycopodiopsida - clubmosses
Selaginellopsida - spikemosses
Isoetopsida - quillworts and scale trees
†
Zosterophyllopsida - zosterophylls
}}
The Division
Lycopodiophyta (sometimes called
Lycophyta) is a
tracheophyte subdivision of the Kingdom
Plantae. It is the oldest extant (living)
vascular plant division at around 420 million years old, and includes some of the most "primitive" extant species. These species reproduce by shedding
spores and have macroscopic
alternation of generations, although some are
homosporous while others are
heterosporous. They differ from all other vascular plants in having
microphylls, leaves that have only a single vascular trace (vein) rather than the much more complex megaphylls found in
ferns and
seed plants.
There are around 1,200 living species divided into three main groups within the Lycopodiophyta, sometimes separated at the level of order and sometimes at the level of class. These are subdivided at the class level here:
The members of this division have a long evolutionary history, and
fossils are abundant worldwide, especially in coal
deposits. In fact, most known
genera are
extinct. The
Silurian species
Baragwanathia longifolia represents the earliest identifable Lycopodiophyta, while some
Cooksonia seem to be related.
Fossils ascribed to the Lycopodiophyta first appear in the Silurian period, along with a number of other vascular plants. Phylogenetic analysis places them at the base of the vascular plants; they're distinguished by their
microphylls and by transverse dehiscence of their sporangia (as contrasted with longitudinal in other vascular plants). Sporangia of living species are borne on the upper surfaces of microphylls (called
sporophylls). In some groups, these sporophylls are clustered into
strobili.
Club-mosses are
homosporous, but spike-mosses and quillworts are
heterosporous, with female spores larger than the male, and gametophytes forming entirely within the spore walls.
During the
Carboniferous period, tree-like Lycopodiophyta (such as
Lepidodendron) formed huge forests and dominated the land. Unlike modern trees, leaves grew out of the entire surface of the trunk and branches, but would fall off as the plant grew, leaving only a small cluster of leaves at the top. Their remains formed many fossil
coal deposits. In Fossil Park,
Glasgow,
Scotland, fossilized Lycopodiophyta trees can be found in
sandstone. The trees are marked with diamond-shaped scars where they once had leaves.
The spores of Lycopodiophyta are highly flammable and so have been used in
fireworks. Currently,
huperzine, a chemical isolated from a
Chinese clubmoss, is under investigation as a possible treatment for
Alzheimer's disease.
Further Information
Get more info on 'Lycopodiophyta'.
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