Chara (alga)
Chara Temporal range:
| |
---|---|
Chara globularis | |
Scientific classification | |
(unranked): | Viridiplantae |
(unranked): | Charophyta |
Class: | Charophyceae |
Order: | Charales |
Family: | Characeae |
Genus: | Chara L., 1753 |
Species | |
See text. |
Chara is a genus of charophyte green algae in the family Characeae. They are multicellular and superficially resemble land plants because of stem-like and leaf-like structures. They are found in freshwater, particularly in limestone areas throughout the northern temperate zone, where they grow submerged, attached to the muddy bottom. They prefer less oxygenated and hard water and are not found in waters where mosquito larvae are present.[2] They are covered with calcium carbonate (CaCO3) deposits and are commonly known as stoneworts. Cyanobacteria have been found growing as epiphytes on the surfaces of Chara, where they may be involved in fixing nitrogen, which is important to plant nutrition.[3]
Structure
The branching system of Chara species is complex with branches derived from apical cells which cut off segments at the base to form nodal and internodal cells alternately.
Morphology
The plant body is a gametophyte. It consists of the main axis (differentiated into nodes and internodes), dimorphic branches (long branch of unlimited growth and short branches of limited growth), rhizoids (multicellular with oblique septa) and stipulodes (needle-shaped structures at the base of secondary laterals).[citation needed]
Reproduction
Chara reproduces vegetatively and sexually. Vegetative reproduction takes place by tubers, amylum stars and secondary protonemata. The sex organs are a multicellular and jacketed globule or antheridium (male) and nucule or archegonium (female). The antheridia and archegonia may occur on separate plants (dioicy), together on the same plant (conjoined monoicy) or separately on the same plant (sejoined monoicy).[6]
The reproductive organs of the Charales show a high degree of specialization. The female organ, called an oogonium is a large oval structure with an envelope of spirally arranged, bright green filaments of cells. The male organ or is also large, bright yellow or red in colour, spherical in shape, and is usually termed an antheridium, though some workers regard it as a multiple structure rather than a single organ. The sex organs are developed in pairs from the adaxial nodal cell at the upper nodes of the primary lateral branches, the oogonium being formed above the antheridium. They are sufficiently large to be easily seen with the naked eye, especially the bright orange or red antheridium. Many species are dioecious. In others the monoecious condition is complicated by the development of the antheridium before the formation of the oogonium, thus preventing fertilization by antherozoids of the same alga. In this case the two types of sex organs usually arise from different points on the lateral branches.
All cells of the Charales are
Species
- Chara braunii ("Report". Integrated Taxonomic Information System.)
- Chara canescens ("Report". Integrated Taxonomic Information System.)
- Chara contraria ("Report". Integrated Taxonomic Information System.) opposite stonewort
- Chara corallina ("Report". Integrated Taxonomic Information System.)
- Chara elegans ("Report". Integrated Taxonomic Information System.)
- Chara excelsa ("Report". Integrated Taxonomic Information System.)
- Chara fibrosa ("Report". Integrated Taxonomic Information System.)
- Chara formosa ("Report". Integrated Taxonomic Information System.)
- Chara fragilis ("Report". Integrated Taxonomic Information System.)
- Chara globularis ("Report". Integrated Taxonomic Information System.)
- Chara hispida ("Report". Integrated Taxonomic Information System.)
- Chara hornemannii ("Report". Integrated Taxonomic Information System.)
- Chara intermedia ("Report". Integrated Taxonomic Information System.)
- Chara nataklys
- Chara sejuncta ("Report". Integrated Taxonomic Information System.)
- Chara virgata ("Report". Integrated Taxonomic Information System.)
- Chara vulgaris ("Report". Integrated Taxonomic Information System.)
- Chara zeylanica ("Report". Integrated Taxonomic Information System.)
- Chara connivens (convergent stonewort)
- Chara wallichii
Distribution
This section needs expansion. You can help by adding to it. (December 2012) |
Chara has a cosmopolitan distribution, from 69 degrees north in northern Norway to about 49 degrees south in Kerguelen Islands (Pal et al., 1962). About 27 species are found in India.[8] There are about 40 species of Chara in Europe, where they are commonly found in the specific habitat-type designated as H3140 (hard oligo-mesotrophic waters with benthic vegetation of Chara spp h1) in the Natura 2000 plans of the European Union. Although this habitat is found all across Europe, it is threatened and to be protected and preserved.
Denmark. Here, many former Chara habitats (H3140) have been polluted by either toxins or excessive amounts of nutrients (in particular phosphates and nitrogen), but a few large lakes and ponds remain. Chara is found growing in the very clean hard water lakes of Thy National Park like Nors Sø for example. Tissø lake (fourth-largest lake in Denmark) is also a H3140 habitat and contains Chara species.[10][11]
Ireland:- Co. Galway. Eglinton Canal Chara virgata Kütz., Chara rudis (A.Braun) Leonhardii and Nitella flexilis (L.) C.Agardh.[12]
References
- ISBN 978-0-7566-5573-0
- JSTOR 4577099.
- .
- ^ a b Round, F.E. 1965.The Biology of the algae. Ernest Arnold.
- ^ Bryant, J. 2007. The Stoneworts (Chlorophyta. Charales) in Guiry, M.D., John, D.M., Rindi, F. and McCarthy, T.K. 2007. New Survey of Clare Island. Volume 6: The Freshwater and Terrestrial Algae. Royal Irish Academy
- JSTOR 2439818.
- ^ Dinesh Sharma (2016-02-04). "Chara: Occurrence, Structure and Reproduction".
- ISBN 9780070681767
- ^ H3140 – Hard oligo-mesotrophic waters with benthic vegetation of Chara spp h1. Archived December 27, 2013, at the Wayback Machine
- ^ 3140 Hard oligo-mesotrophic waters with benthic vegetation of Chara spp h1. Archived December 27, 2013, at the Wayback Machine Danish Nature agency (in Danish)
- ISBN 978-87-7091-034-7
- ^ Pybus, C. and O'Halloran, P. 2009. Distribution of some submerged aquatic macrophytes in Eglinton Canal, Galway. Ir. Nat. J. 30: 51 – 53