Definitions

Charales

Charales

The Charales are algae in the division Charophyta. They are green plants believed to be the closest relatives of the green land plants. Linnaeus established the genus (Chara) in 1753.

Description

The Charales, have large, macroscopic, thalli growing up to 120cm long, they are branched, multicellular, and use chlorophyll to photosynthesize. They grow in fresh water. They may be called stoneworts, because the plants can become encrusted in lime (calcium carbonate) after some time. The "stem" is actually a central stalk consisting of giant, multinucleated cells. They are unique in having a whorl of small branchlets at each node in the stipe, this gives them a superficial resemblance to the genus Equisetum. In these whorls it is possible to see the phenomenon of cytoplasmic streaming very well. In fact the streaming in Chara is the fastest recorded of any cell. Cytoplasmic streaming is caused by the microfilaments found inside the cell, as proven by the use of cytochalasin B to stop streaming. There are about 400 species world-wide, with 33 in Britain and Ireland according to Groves and Bullock-Webster), however (Stewart and Church (1992) reduce this to 21.

Species

British Isles

Ref: Stewart & Church (1992).

  • Chara baltica Bruz.
  • Chara canescens Desv. & Lois.
  • Chara connivens Salzm. ex A.Braun
  • Chara curta Nolta wx Kütz. (=C.aspera var. curta)
  • Chara denudata (A.Braun) R.D.Wood
  • Chara fragifera Durieu
  • Chara intermedia Braun (=C. papillosa Kütz. and C. contraria x hispida)
  • Chara mucosa J.Groves & Bullock-Webster
  • Chara rudis (A.Braun) Leonh.
  • Chara tomentosa L.
  • Lamprothamnium papulosum (Wallr.) J.Groves
  • Nitella capillaris (Krocker) J.Groves & Bullock-Webster
  • Nitella gracilis (Smith) Agardh
  • Nitella hyalina (DC.)Agardh
  • Nitella mucronata (A.Braun)Miquel
  • Nitella spanioclema J.Groves & Bullock-Webster (Nitella flexilis var. spanioclema (J.Groves & Bullock-Webster)
  • Nitella tenuissima (Desv.) Kütz.
  • Nitellopsis obtusa (Desv.) J.Groves
  • Topella intricata (Trent. ex Roth) Leonh.
  • Tolypella nidifica (O.F.Müll.) Leonh. (= Tolypella nidifica var. nidifica)
  • Tolypella prolifera (Ziz. ex A.Braun) Leonh.

Other regions

Distribution

Ireland

  • Co. Antrim
    • C.aspera Deth. ex Willd. var. aspera
    • C. globularis Thuill. var. globularis
    • C. vulgaris var. papillata Wallr. ex A. Braun
    • C. globularis var. virgata (Kützing) R.D.Wood
    • C. vulgaris L. var. vulgaris
    • C. vulgaris L. var. contraria (A.Braun ex Kützing) J.A. Moore
    • C. vulgaris var. longibracteata (Kützing) J. Groves & Bullock-Webster
    • C. vulgaris var. papillata Wallr. ex A. Braun
    • Nitella flexilis (L.) var. flexilis
    • Nitella translucens (Pers.) C.A. Ag.
    • Tolypella nidifica (O. Mill.) Leonh. var. glomerata (Desv.) R.D.Wood
  • Co. Down
    • C. aspera Deth. ex Willd. var. aspera
    • C. aspera var. curta (Nolte ex Kützing) Braun ex Leonh.
    • C. globularis Thuill. var. globularis
    • C. vulgaris var. papillata Wallr. ex A. Braun
    • C. globularis var. virgata (Kützing) R.D.Wood
    • C. globularis var. annulata (Lilleblad) J.A.Moore
    • C. hispida L.
    • C. hispida var. hispida
    • C. hispida var. major (Hartm.) R.D. Wood
    • C. hispida var. rudis A. Braun
    • C. pedunculata Kützing
    • C. vulgaris L. var. vulgaris
    • C. vulgaris L. var. contraria (A.Braun ex Kützing) J.A. Moore
    • C. vulgaris var. longibracteata (Kützing) J. Groves & Bullock-Webster
    • C. vulgaris var. papillata Wallr. ex A. Braun
    • Nitella flexilis (L.) var. flexilis
    • Nitella translucens (Pers) C.A. Ag.
    • Tolypella nidifica (O. Mill.) Leonh. var. glomerata (Desv.) R.D.Wood
  • Co. Londonderry
    • C.aspera Deth. ex Willd. var. aspera
    • C. vulgaris var. papillata Wallr. ex A. Braun
    • C. globularis Thuill. var. globularis
    • C. globularis var. virgata (Kützing) R.D.Wood
    • C. hispida L.
    • C. hispida var. hispida
    • C. vulgaris L. var. vulgaris
    • C. vulgaris L. var. contraria (A.Braun ex Kützing) J.A. Moore
    • C. vulgaris var. papillata Wallr. ex A. Braun
    • Nitella flexilis (L.) var. flexilis
    • Nitella translucens (Pers) C.A. Ag.
    • Tolypella nidifica (O. Mill.) Leonh. var. glomerata (Desv.) R.D.Wood
  • Co. Mayo.Recent records have been published from Clare Island.
    • C. virgata Kützing
    • N. flexilis (Linnaeus) C.Agardh
    • N. translucens (Persoon) C.Agardh

Ecology

The Characeae because of the are aquatic though some can survive in brackish or maritime habitats. They are to be found usually in still, clear, non-flowing, water attached by rhizoids. They can be pioneer colonizers or ephemerals. They are usually found in low to medium nutrient-rich water and tend to disappear due to eutrophication.

Life history

The antheridia and oogonia are protected by a layer of sterile cells when mature; the oogonium is oblong in shape and consists of a single egg, while the spherical antheridium is packed with threadlike cells that produce spermatia. As a result, the Charales have the most complex structure of all green algae, if indeed they should be so labelled.

The possible ancestors of the land plants are also known as brittleworts or skunkweed. These curious labels arise from the fragility of their lime-encrusted stems, and from the foul odor these produce when stepped on.

Many botanists propose that the stoneworts and their relatives be placed in a phylum, division, sub-kingdom, or even kingdom by themselves, often named Charophyta. Their classification by taxonomists is currently undergoing much cladistic scrutiny. Further DNA and RNA analysis may prove the charophytes to be a crucial evolutionary link in the phylogenetic tree of life, the critical developmental step from the algae toward the non-vascular and then vascular land plants.

References

Further reading

  • Bryant, J. The stoneworts (Chlorophyta, Charales). In Guiry, M.D., John, D.M., Rindi, F. and McCarthy, T.K. 2007. New Survey of Clare Island. Royal Irish Academy. ISBN-13:978--904890-31-7.
  • Lloyd, James. 2007. "Cytoskeletal Structures Responsible for Cytoplasmic Streaming in Chara." St. Vincent-St. Mary High School in Accordance with Dr. Donald Ott of The University of Akron. (Science Inquiry)
  • Morton, O. 1992. Charophyta. pp.91 - 94 in Hackney, P. (Ed) 1992 Stewart and Corry's Flora of the North-east of Ireland. Third edition. Institute of Irish Studies. The Queen's University of Belfast.
  • Schaible, R. and Schubert, H. 2008. The ccurrence of sexual Chara canesces populations (Charophyceae) is not related to ecophysiological potentials with respect to salinity and irradiance. Eur. J. Phycol. 43: 309 - 316.

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