Lycopodiophytes
| Lycopodiophyta Temporal range: 428–0 Ma Silurian to recent |
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|---|---|
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| Lycopodiella inundata | |
| Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Division: |
Lycopodiophyta D.H.Scott 1900 |
| Classes | |
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Lycopodiopsida - clubmosses |
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Lycopodiopsida - clubmosses
Isoetopsida - spikemosses, quillworts, scale trees
† Zosterophyllopsida - zosterophylls
The Division Lycopodiophyta (sometimes called lycophyta or lycopods) is a tracheophyte subgroup of the Kingdom Plantae. It is one of the oldest lineages of extant (living) vascular plants and contains extinct plants like Baragwanathia that have been dated from the Silurian (ca. 425 million years ago). These species reproduce by shedding spores and have macroscopic alternation of generations, although some are homosporous while others are heterosporous. Most members of Lycopodiophyta bear a protostele, and the sporophyte generation is dominant. 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 1,290 (Christenhusz & Byng 2016 ) living (extant) species of Lycopodiophyta which are generally divided into three extant orders (Lycopodiales, Isoetales, and Selaginellales), in addition to extinct groups. There is some variation in how the extant orders are grouped into classes: they may be put into a single class; they may be put into two classes, with the Isoetales and Selaginellales combined into one class; or they may be put into three classes, one order in each. The system which uses two classes for extant species is:
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