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Lycopodiophyta
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{{Taxobox
| color = lightgreen
| name = Lycopodiophyta
| image = Lycopodium_plant.jpg
| image_width = 250px
| image_caption = ''Lycopodiella cernua''
| regnum =
Plantae
| divisio = Lycopodiophyta
| subdivision_ranks =
Class (biology) Classes
| subdivision =
Lycopodiopsida - clubmosses
Spikemoss Selaginellopsida - spikemosses
Quillwort Isoetopsida - quillworts
}}
The Division '''Lycopodiophyta''' (sometimes called '''Lycophyta''') is a
vascular plant tracheophyte subdivision of the Kingdom
plant Plantae. It is the oldest extant (living) vascular plant division 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 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
Spikemoss Selaginellopsida – spikemosses
*Class
Quillwort Isoetopsida – quillworts
The members of this division have a long evolutionary history, and
fossils are abundant worldwide, especially in coal
deposits. In fact, most known
Genus genera are
Extinction extinct. The Silurian species ''
Baragwanathia longifolia'' represents the earliest identifable Lycopodiophyta, while some ''
Cooksonia'' seem to be related.
The Lycopodiophyta are one of several classes of plants that expanded onto land during the
Silurian and
Devonian periods. Like all explorers it found new hazards that demanded new solutions. While the ocean currents blended
oxygen,
water and nutrients into a soup, the land had a layered structure with water and
minerals in the
soil and oxygen and light in the air. The intense sunlight presented a greater risk of
Genetics genetic damage. Without water, pervasive desiccation became a possibility, and more structural support was required to resist
gravity.
Many adaptations of the Lycopodiophyta can be explained as a response to these conditions. They continued the development and specialization of roots to extract
nutrients from the
soil and developed leaves for
photosynthesis and
Cellular respiration gas exchange, using a stem for transport. A waxy cuticle helped retain moisture, and stoma allowed respiration. The vulnerable meiotic
gametophyte is protected from
radiation by its reduced size and often by the use of subterranean mycorhiza for its energy source instead of photosynthesis. Club-mosses are ''homosporous'', but spike-mosses and quillworts are ''heterosporous''. In heterospores the female spores are larger than the male because they store food for the new generation.
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
China Chinese clubmoss, is under investigation as a possible treatment for
Alzheimer's disease.
External links
{{Wikispecies|Lycopodiophyta}}
{{Wikibookspar|Dichotomous Key|Lycopodiophyta}}
*[http://www.ucmp.berkeley.edu/plants/lycophyta/lycophyta.html]
-
Fossil Groves
-
More About Lycopsids
-
Paleo Plants
-
The First Land Plants
Category:Fossils
Category:Lycopodiophyta
bg:Плауновидни
cs:PlavunÄ›
de:Bärlapppflanzen
fr:Lycophyte
he:בעלי קשקשי×?
lt:Pataisūnai
mk:Ликоподиумови раÑ?тенија
no:Kråkefotplanter
fi:Liekomaiset
pt:Lycophyta
sv:Lummerväxter
{{sisterlinkswp|Category:Lycopodiophyta}}
The division
Lycopodiophyta includes the
clubmosses,
spikemosses and
quillworts. Many are considered "
fern allies".
Category:Plants sort21 Lycopodiophyta
Category: plant taxonomy sort21 Lycopodiophyta
Category:Cryptogams
bg:КатегориÑ?:Плауновидни
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