Thallophytes (Thallophyta, Thallophyto or Thallobionta) are a polyphyletic group of non-motile organisms traditionally described as "thalloid plants", "relatively simple plants" or "lower plants". They form a division of kingdom Plantae that include lichens and algae and occasionally bryophytes, bacteria and slime moulds. Thallophytes have a hidden reproductive system and hence they are also incorporated into the similar Cryptogamae category (together with ferns), as opposed to Phanerogamae. Thallophytes are defined by having undifferentiated bodies (thalloid, pseudotissue), as opposed to cormophytes (Cormophyta) with roots and stems. Various groups of thallophytes are major contributors to marine ecosystems.
Several different definitions of the group have been used. Thallophytes (Thallophyta or Thallobionta) are a polyphyletic group of non-mobile organisms traditionally described as "thalloid plants", "relatively simple plants" or "lower plants". Stephan Endlicher, a 19th-century Austrian botanist, separated the vegetable kingdom into the thallophytes (algae, lichens, fungi) and the cormophytes (including bryophytes and thus being equivalent to Embryophyta in this case) in 1836. This definition of Thallophyta is approximately equivalent to Protophyta, which has always been a loosely defined group.
In the Lindley system (1830–1839), Endlicher's cormophytes were divided into the thallogens (including the bryophytes), and cormogens ("non-flowering" plants with roots), as well as the six other classes. Cormogens were a much smaller group than Endlicher's cormophytes, including just the ferns (and Equisetopsida) and the plants now known as lycopodiophytes.
The first ten phyla are referred to as thallophytes. They are simple plants without roots stems or leaves.
They are non-embryophyta. These plants grow mainly in water.
The Thallophyta have been divided into two subdivisions:
- Myxothallophyta (myxomycetes)
- Euthallophyta (bacteria, fungi, lichens, algae)
- Stephan Endlicher (1836–1840). "Genera plantarum secundum ordines naturales disposita". F. Beck; The Biodiversity Heritage Library.
- Lindley (1846), page 46
- Fritsch, F.E. (1929). "Evolutionary Sequence and Affinities among Protophyta". Biological Reviews. 4 (2): 103–151. doi:10.1111/j.1469-185X.1929.tb00884.x. S2CID 85070857.
- Lindley (1846), page 49
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- Awasthi 2010, p. 226.
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