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Polysiphonia Atlantica
''Polysiphonia atlantica'' is a small filamentous species of red marine algae Rhodophyta. The thalli form small tufts up to 3 cm long. The axes are ecorticate consisting of axial cells surrounded by four periaxial cells.Maggs, C.A. and Hommersand, M.H. 1993 ''Seaweeds of the British Isles. Volume 1 Rhodophyta Part 3A Ceramiales.'' The Natural History Museum, London. Description ''Polysiphonia atlantica'' is a small alga 3 cm high and dark reddish-brown in colour. It grows in tufts from prostrate axes producing numerous erect branches all growing to the similar lengths. The axial cells are surrounded by 4 periaxial cells which are elongate to the same length as the axial cells which are ecorticate. Attached by rhizoids produced by the periaxial cells. Reproduction The life history is a sequence of three phases: gametangial, carposporangial and tetrasporangial.Dixon, P.S. ''Biology of the Rhodophyta.'' p.187. Oliver & Boyd. The plants are dioecious with spermatangial br ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Algae
Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular microalgae, such as cyanobacteria, ''Chlorella'', and diatoms, to multicellular macroalgae such as kelp or brown algae which may grow up to in length. Most algae are aquatic organisms and lack many of the distinct cell and tissue types, such as stomata, xylem, and phloem that are found in embryophyte, land plants. The largest and most complex marine algae are called seaweeds. In contrast, the most complex freshwater forms are the Charophyta, a Division (taxonomy), division of green algae which includes, for example, ''Spirogyra'' and stoneworts. Algae that are carried passively by water are plankton, specifically phytoplankton. Algae constitute a Polyphyly, polyphyletic group because they do not include a common ancestor, and although Eu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhodophyta
Red algae, or Rhodophyta (, ; ), make up one of the oldest groups of eukaryotic algae. The Rhodophyta comprises one of the largest phyla of algae, containing over 7,000 recognized species within over 900 genera amidst ongoing taxonomic revisions. The majority of species (6,793) are Florideophyceae, and mostly consist of multicellular, marine algae, including many notable seaweeds. Red algae are abundant in marine habitats. Approximately 5% of red algae species occur in freshwater environments, with greater concentrations in warmer areas. Except for two coastal cave dwelling species in the asexual class Cyanidiophyceae, no terrestrial species exist, which may be due to an evolutionary bottleneck in which the last common ancestor lost about 25% of its core genes and much of its evolutionary plasticity. Red algae form a distinct group characterized by eukaryotic cells without flagella and centrioles, chloroplasts without external endoplasmic reticulum or unstacked (stroma) thylako ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cystocarp
A cystocarp is the fruiting structure produced in the red algae after fertilization, especially such a structure having a special protective envelope (as in ''Polysiphonia)''. The structure from which carpospore A carpospore is a diploid spore produced by red algae Red algae, or Rhodophyta (, ; ), make up one of the oldest groups of eukaryotic algae. The Rhodophyta comprises one of the largest Phylum, phyla of algae, containing over 7,000 recognized spe ...s are released.Maggs, C.A. and Hommersand, M.H. 1993. ''Seaweeds of the British Isles Volume 1 Rhodophyta Part 3A Ceramiales.'' The Natural History Museum, London References Algal anatomy {{Rhodophyta-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Isles
The British Isles are an archipelago in the Atlantic Ocean, North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner Hebrides, Inner and Outer Hebrides, Outer Hebrides, the Northern Isles (Orkney and Shetland), and over six thousand smaller islands. They have a total area of and a combined population of almost 72 million, and include two sovereign states, the Republic of Ireland (which covers roughly five-sixths of Ireland), and the United Kingdom, United Kingdom of Great Britain and Northern Ireland. The Channel Islands, off the north coast of France, are normally taken to be part of the British Isles, even though geographically they do not form part of the archipelago. Under the UK Interpretation Act 1978, the Channel Islands are clarified as forming part of the British Islands, not to be confused with the British Isles. The oldest rocks are 2.7 billion years old and are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
