Anabaena Bory de Saint-Vincent ex Bornet & Flahault 1886: 224.
Type species: Anabaena oscillarioides Bory de Saint-Vincent
Currently accepted name for type species:Anabaena pseudoscillatoria Bory de Saint-Vincent
Source: Kom?rek, J., Kling, H. & Kom?rkov?, J. (2003). Filamentous Cyanobacteria. In: Freshwater Algae of North America. (Wehr, J.D. & Sheath, R.G. Eds), pp. 177-196. San Diego: Academic Press.
Classification: Empire Prokaryota Kingdom Bacteria Subkingdom Negibacteria Phylum Cyanobacteria Class Cyanophyceae Subclass Nostocophycideae Order Nostocales Family Nostocaceae Genus Anabaena
Description: Filaments solitary or in free clusters (subg. Dolichospermum) or in macroscopic mats on the substrate (subg. Anabaena), usually with coiled and tangled, sometimes up to screw-like coiled, rarely with more or less parallel oriented trichomes, along the length of the same width or slightly narrowed to the ends, with more or less deep constrictions at crosswalls, always without firm sheaths, but sometimes with mucilaginous, hyaline, colorless, often diffluent envelopes; trichomes uniseriate, often moniliform, isopolar, always metameric. (Heterocytes develop solitary and intercalary in more or less certain distances from one another; in one developed trichome always 3-9, rarely more, heterocytes.) Cells cylindrical, barrel-shaped or spherical, shorter to longer than wide, pale or bright blue-green or olive-green, containing aerotopes (subg. Dolichospermum) or without aerotopes, but sometimes with granular content (subg. Anabaena); terminal cells sometimes slightly elongated, conical, conical rounded or spherical, not vacuolized. Heterocytes spherical, widely oval or cylindrical, sometimes elongated, usually slightly greater than vegetative cells. Akinetes spherical, oval or cylindrical, solitary or several in a row, intercalary, developing always paraheterocytic, close to heterocytes from both sides, or slightly distant from them. Cells divide transversely and grow to the original size before the next division; without meristematic zones. Reproduction by trichome fragmentation (usually at heterocytes) and by akinetes. Planktonic species, sometimes forming aquatic blooms (mainly from the subg. Dolichospermum) or in mats covering different substrates, aquatic plants, submerged wood, stones, etc. Several species benthic or in soils, several are known from saline (brackish) habitats. Many species have limited geographic areas of distribution, but this genus is widespread and common.
Numbers of names and species: There are 526 species names in the AlgaeBase species database at present, of which 94 is/are flagged as current.