Thallophyta


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Thallophyta

[thə′läf·əd·ə]
(botany)
The equivalent name for Thallobionta.

Thallophyta

 

one of the two subkingdoms of the plant world; it comprises bacteria, actinomycetes, myxomycetes, fungi, algae, and lichens. The body of thallophytes, the thallus, is not divided into a root, stem, and leaf; multicellular reproductive organs are absent.

Thallophytes include procaryotes, cells lacking a true nucleus (bacteria, actinomycetes, blue-green algae), and eucaryotes, cells with a true nucleus (the remaining members of the subkingdom). They are unicellular (mostly microscopic) or multicellular (up to 40 m long) and heterotrophic (most bacteria, actinomycetes, myxomycetes, fungi) or autotrophic (some bacteria, algae [including those living in lichens]). The more highly organized thallophytes have leaflike organs and a conducting system similar to the phloem of higher plants; the zygote develops in a multicellular embryo on a gametophyte (some brown algae).

Fossil remains of several thallophytes—bacteria and unicellular algae—have been found in Archean and Proterozoan deposits about 3 billion years old.

REFERENCES

Kursanov, L. I., and N. A. Komarnitskii. Kurs nizshikh rastenii, 3rd ed. Moscow, 1945.
Malyi praktikum po nizshim rasteniiam. Moscow, 1967.

IU. E. PETROV