The Nostocaceae are a family of

cyanobacteria Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...

that forms

filament The word filament, which is descended from Latin ''filum'' meaning " thread", is used in English for a variety of thread-like structures, including: Astronomy * Galaxy filament, the largest known cosmic structures in the universe * Solar filament ...

-shaped

colonies A colony is a territory subject to a form of foreign rule, which rules the territory and its indigenous peoples separated from the foreign rulers, the colonizer, and their '' metropole'' (or "mother country"). This separated rule was often or ...

enclosed in

mucus Mucus (, ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both Serous fluid, serous and muc ...

or a gelatinous sheath. Some genera in this family are found primarily in fresh water (such as ''

Nostoc ''Nostoc'', also known as star jelly, troll's butter, spit of moon, fallen star, witch's butter (not to be confused with the fungi commonly known as witches' butter), and witch's jelly, is the most common genus of cyanobacteria found in a variety ...

''), while others are found primarily in salt water (such as '' Nodularia''). Other genera (e.g. ''

Anabaena ''Anabaena'' is a genus of filamentous cyanobacteria that exist as plankton. They are known for nitrogen-fixing abilities, and they form symbiotic relationships with certain plants, such as the mosquito fern. They are one of four genera of cyan ...

'') may be found in both fresh and salt water. Most benthic algae of the order Nostocales belong to this family. Like other cyanobacteria, these bacteria sometimes contain photosynthetic

pigment A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...

s in their cytoplasm to perform

photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

. The particular pigments they contain gives the cells a bluish-green color. Species of the Nostocaceae are particularly known for their

nitrogen-fixing Nitrogen fixation is a chemical process by which molecular dinitrogen () is converted into ammonia (). It occurs both biologically and abiological nitrogen fixation, abiologically in chemical industry, chemical industries. Biological nitrogen ...

abilities, and they form

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

relationships with certain

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

s, such as the

mosquito fern ''Azolla'' (common called mosquito fern, water fern, and fairy moss) is a genus of seven species of aquatic ferns in the family Salviniaceae. They are extremely reduced in form and specialized, having a significantly different appearance to ot ...

cycad Cycads are seed plants that typically have a stout and woody (ligneous) trunk (botany), trunk with a crown (botany), crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants o ...

s, and

hornwort Hornworts are a group of non-vascular Embryophytes (land plants) constituting the division Anthocerotophyta (). The common name refers to the elongated horn-like structure, which is the sporophyte. As in mosses and liverworts, hornworts have a ...

s. The cyanobacteria provide nitrogen to their hosts. Certain species of ''Anabaena'' have been used on rice paddy fields. Mosquito ferns carrying the cyanobacteria grow on the water in the fields during the growing season. They and the nitrogen they contain are then plowed into the soil following the harvest, which has proved to be an effective natural fertilizer. The family Nostocaceae belongs to the order

Nostocales The Nostocales are an order of cyanobacteria Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (c ...

. Members of the family can be distinguished from those in other families by their unbranched filaments of cells arranged end-to-end, and development of

heterocyst Heterocysts or heterocytes are specialized nitrogen-fixing cells formed during nitrogen starvation by some filamentous cyanobacteria, such as ''Nostoc'', ''Cylindrospermum'', and '' Anabaena''. They fix nitrogen from dinitrogen (N2) in the air ...

s among the cells of the filaments.

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Microscopy U

{{Authority control Cyanobacteria families

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Further reading

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