Lycopod

The Lycopods (Lycopodiophyta or Lycophyta) are the oldest surviving vascular plant division. This is a subdivision of the plant kingdom. Its earliest fossils are from 428–410 million years ago.^[3][4]p99

Lycopod Temporal range: Silurian to Recent
Lycopodiella inundata
Scientific classification
Kingdom:	Plantae
Division:	Lycopodiophyta Cronquist, Takht. & W.Zimm.[1][2]

External impression of Lepidodendron from the Upper Carboniferous of Ohio

The Lycopods include some of the most primitive (basal) living species. They reproduce by shedding spores and have macroscopic alternation of generations.^[5] Members of Lycopodiophyta have a protostele,^[6] and the sporophyte generation is dominant.^[7][8]

Lycopods differ from all other vascular plants in having microphylls, leaves that have only a single vein rather than the much more complex megaphylls found in ferns and seed plants.

The first coalfields

The lycopods, or club mosses, are the main plants in the Carboniferous rain forests. They were only partly eaten by insects and other life-forms. Mostly they formed swamplands which in the course of time became coal measures. In fact most of the coal from the Carboniferous period comes from these swamplands.^[9]

Classification

There are around 1,200 living species of Lycopodiophyta; they are generally divided into three orders.^[10] There are also some extinct groups. There are different opinions as to how the whole group should be classified.^[11][12]p8 Living groups are:

• Lycopodiales: Clubmosses
• Isoetales: Quillworts
• Selaginellales: Spikemosses

References

1. Cronquist, A; Takhtajan, A.; Zimmermann, W. (1966). "On the higher taxa of Embryobionta". Taxon. 15 (15): 129–134. doi:10.2307/1217531. JSTOR 1217531.
2. Cantino, Philip D.; et al. (2007). "Towards a phylogenetic nomenclature of Tracheophyta". Taxon. 56 (3): E1–E44. doi:10.1002/tax.563001.
3. Kenrick, Paul; Crane, Peter R. (1997). The origin and early diversification of land plants: a cladistic study. Washington D.C.: Smithsonian Institution Press. pp. 339–340. ISBN 1-56098-730-8.
4. McElwain, Jenny C; et al. (2002). The evolution of plants. Oxford: Oxford University Press. ISBN 0-19-850065-3.
5. 'macroscopic' = can be seen with the naked eye, e.g. instead of requiring a microscope
6. A central core of vascular tissue which conducts water and nutrients up, and manufactured substances down. The stele also supports the plant above the ground.
7. The sporophyte generation is diploid, and produces the spores. The spores produce the haploid gametophyte generation.
8. Eichhorn, Evert, and Raven 2005. Biology of plants, 7th ed. 381-388.
9. Gensel P.G. & Edwards D. (eds). Plants invade the land : evolutionary & environmental perspectives. New York: Columbia University Press. ISBN 978-0-231-11161-4
10. Callow, R.S.; Cook, Laurence Martin (1999). Genetic and evolutionary diversity: the sport of nature. Cheltenham: S. Thornes. p. 8. ISBN 0-7487-4336-7.
11. Yatsentyuk, S.P.; et al. (2001). "Evolution of Lycopodiaceae inferred from spacer sequencing of chloroplast rRNA genes". Russian Journal of Genetics. 37 (9): 1068–73. doi:10.1023/A:1011969716528. S2CID 22187626.
12. Schoch CL; et al. (2020). "NCBI Taxonomy: a comprehensive update on curation, resources and tools". Database : The Journal of Biological Databases and Curation. 2020. doi:10.1093/database/baaa062. PMC 7408187. PMID 32761142. Retrieved 2009-03-19.