(botany) A division of the subkingdom Embryobionta characterized by a dominant independent sporophyte, dichotomously branching roots and stems, a single vascular bundle, and small, simple, spirally arranged leaves.
Lycopodiophyta
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Lycopodiophyta (lī'kōpō'dēŏf'ətə) , division of the plant kingdom consisting of the organisms commonly called club mosses and quillworts. As in other vascular plants, the sporophyte, or spore-producing phase, is the conspicuous generation, and the gametophyte, or gamete-producing phase, is minute. The living representatives are all rather small herbaceous plants, usually with branched stems and small leaves, but their fossil ancestors were trees. Like other vascular plants, the axes of this group have epidermis, cortex, and a central cylinder, or stele, of conducting tissue. The spore cases, or sporangia, are borne at the base of leaves, either scattered along the stem or clustered into a terminal cone or strobilus. At maturity, the sporangia split across the top, releasing great quantities of spores. The spores germinate to produce small, nongreen, fleshy gametophytes, which bear both sperm-producing antheridia and egg-producing archegonia. The motile sperms swim to the egg through a film of water. The fertilized egg, or zygote, gives rise to an embryo and eventually to a mature sporophyte. The order Lycopodiales includes the common genus Lycopodium, the larger of two genera (the other is Phylloglossum) belonging to this order and containing some 100 species. The order Selaginellales contains only one living genus, Selaginella, with perhaps 600 species, although fossil forms resembling Selaginella are known from deposits of the Carboniferous period (see resurrection plant). The order Isoetales (quillworts) contains the small genus Isoetes, which grows in shallow water in lakes, ponds, and marshy places. The plants have a grasslike appearance and are therefore often not readily identified. The order Lepidodendrales contains members known only from fossil specimens dating from the Upper Devonian to Permian times. Lepidodendron, the most common genus, was of tree size.
| Wikipedia: Lycopodiophyta |
| Lycopodiophyta Fossil range: 428 Ma Silurian[citation needed] to recent |
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 Lycopodiella cernua
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Lycopodiopsida - clubmosses |
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,[citation needed] 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.
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Classification
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:
- Class Lycopodiopsida – clubmosses and firmosses
- Class Isoetopsida – quillworts and scale trees
- Class Selaginellopsida – spikemosses. These are sometimes classified under Isoetopsida, with the order name "Selaginellales".[3]
Evolution
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 are 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.
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.
Characteristics
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.
The spores of Lycopodiophyta are highly flammable and so have been used in fireworks.[4] Currently, huperzine, a chemical isolated from a Chinese clubmoss, is under investigation as a possible treatment for Alzheimer's disease.
Gallery
 Lycopodites, an early lycopod-like fossil. |
 External mold of Lepidodendron from the Upper Carboniferous of Ohio. |
 Lycopodiophyta spores can be used in pyrotechnics. |
References
- ^ Cronquist, A.; A. Takhtajan, W. Zimmermann (1966). "On the higher taxa of Embryobionta". Taxon 15 (15): 129–134. doi:.
- ^ Cantino, Philip D.; James A. Doyle, Sean W. Graham, Walter S. Judd, Richard G. Olmstead, Douglas E. Soltis, Pamela S. Soltis, & Michael J. Donoghue (2007). "Towards a phylogenetic nomenclature of Tracheophyta". Taxon 56 (3): E1–E44.
- ^ "www.ncbi.nlm.nih.gov". http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Undef&id=3243. Retrieved on 2009-03-19.
- ^ Cobb, B (1956) A Field Guide to Ferns and their related families: Northeastern and Central North America with a section on species also found in the British Isles and Western Europe (Peterson Field Guides), 215
External links
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Wikispecies has information related to: Lycopodiophyta |
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The Wikibook Dichotomous Key has a page on the topic of |
- Introduction to the Lycophyta from the University of California Museum of Paleontology
- Lycophytes
- Fossil Groves
- Paleo Plants
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 | Sci-Tech Dictionary. McGraw-Hill Dictionary of Scientific and Technical Terms. Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by McGraw-Hill Companies, Inc. All rights reserved. Read more |
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| Columbia Encyclopedia. The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/ Read more |
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Mentioned in
- Lycopsida (botany)
- quillwort (plant)
- running pine (plant)
- Isoetopsida (botany)
- Sigillaria (in botany)
- resurrection plant (plant)
- Lepidodendron and Sigillaria (tree – in history)
- club moss (plant, species)
- Embryobionta (embryobionta)
- Lycophyta
- plant (in botany)
- Lycopodium annotinum
- Huperzia selago
- Huperzia megastachya
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