The Ulvophyceae or ulvophytes are a class of

green algae The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as ...

, distinguished mainly on the basis of ultrastructural morphology,

life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring *Life-cycle hypothesis, ...

and

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

data.Graham LE, Graham JM, Wilcox LW (2009) ''Algae''. 2nd Edition. Benjamin Cummings (Pearson), San Francisco, CA The sea lettuce, ''Ulva'', belongs here. Other well-known members include ''

Caulerpa ''Caulerpa'' is a genus of seaweeds in the family Caulerpaceae (among the green algae). They are unusual because they consist of only one cell with many nuclei, making them among the biggest single cells in the world. A species in the Mediterra ...

'', ''

Codium ''Codium'' is a genus of seaweed in the Chlorophyta of the order Bryopsidales. Paul Silva was an expert on the genus ''Codium'' taxonomy at the University of California, Berkeley. There are about 50 species worldwide. Description The genus h ...

'', ''

Acetabularia ''Acetabularia'' is a genus of green algae in the family Polyphysaceae, Typically found in subtropical waters, ''Acetabularia'' is a single-celled organism, but gigantic in size and complex in form, making it an excellent model organism for stud ...

'', ''

Cladophora ''Cladophora'' is a genus of reticulated filamentous Ulvophyceae (green algae). The genus ''Cladophora'' contains many species that are very hard to tell apart and classify, mainly because of the great variation in their appearances, which is ...

'', '' Trentepohlia'' and ''

Monostroma ''Monostroma'' is a genus of marine green algae (seaweed) in the family Monostromataceae. As the name suggests, algae of this genus are monostromatic (single cell layered). '' Monostroma kuroshiense'', an algae of this genus, is commercially cu ...

''. The Ulvophytes are diverse in their

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

and their

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

. Most are

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), '' Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such a ...

s such as those listed above. Others, such as '' Rhizoclonium'', '' Pithophora'' and some species of ''

'' live in fresh water and in some areas are considered

weed A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...

Evolution

The origin and early diversification of the Ulvophyceae likely took place in the late

Neoproterozoic The Neoproterozoic Era is the unit of geologic time from 1 billion to 538.8 million years ago. It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods. It is pre ...

. Although most contemporary ulvophytes are marine macroalgae (

s),

ancestral An ancestor, also known as a forefather, fore-elder or a forebear, is a parent or (recursively) the parent of an antecedent (i.e., a grandparent, great-grandparent, great-great-grandparent and so forth). ''Ancestor'' is "any person from whom ...

ulvophytes may have been freshwater, unicellular green algae. Molecular phylogenetic evidence suggests that macroscopic growth was achieved independently in the various major lineages of Ulvophyceae (

Ulvales Ulvales is an order of green algae. References External links * * Chlorophyta orders {{Ulvophyceae-stub ...

- Ulotrichales, Trentepohliales,

Cladophorales Cladophorales are an order of green algae, in the class Ulvophyceae.See the NCBI The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes ...

Bryopsidales Bryopsidales is an order of green algae, in the class Ulvophyceae. Characteristics The thallus is filamentous and much branched and may be packed into a mass. It is coenocytic, having multi-nucleate cells consisting of cytoplasm contained with ...

and

Dasycladales Dasycladales is an order of large unicellular green algae in the class Ulvophyceae. It contains two families, the Dasycladaceae and the Polyphysaceae. These single celled algae are from 2 mm to 200 mm long. They live on substrate ...

). Fossils are rare but there are some good candidates in a mid-Ordovician lagerstatten. Current hypothesis on relationships among the main clades of Ulvophyceae are shown below.

References

{{Taxonbar, from=Q132016 Green algae classes

Evolution

See also

References