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 of both aquatic and terrestrial environments that may form colonies composed of filaments of moniliform cells in a gelatinous sheath of polysaccharides. It may also grow symbiotically within the tissues of plants, providing nitrogen to its host through the action of terminally differentiated cells known as heterocysts. Nostoc is a genus that includes many species that are diverse in morphology, habitat distribution, and ecological function. Nostoc can be found in soil, on moist rocks, at the bottom of lakes and springs, and rarely in marine habitats. It may also be found in terrestrial temperate, desert, tropical, or polar environments.
The name Nostoc was coined by Paracelsus and is a combination of the English nostril and German Nasenloch "nose hole, nostril", likely due to appearance of many species' colonies being similar to nasal mucus. When it is on the ground, a Nostoc colony is ordinarily not seen, but after a rain, it swells up into a conspicuous, jellylike mass, which was once thought to have fallen from the sky, hence the popular names, like star jelly, troll's butter, and witch's butter mentioned above.
Morphology
left|thumb|Nostoc strains
Nostoc are a genus of Gram-negative photosynthetic cyanobacteria. Some species within the genus also have nitrogen-fixing heterocyst filaments enclosed in this membrane.
Environmental usage
Nostoc has the unique ability to survive and colonize new and bare mineral surfaces by moss and other higher plants, which then allows for more organic soil and stable vegetation. It has been suggested that Nostoc be used in environments of retreating glaciers in order to establish new and more stable presences of vegetation on newly exposed mineral surfaces. Historically, the species N. flagelliforme and N. commune have been consumed in China, where it was used to survive famines and has been used as an ingredient in Chinese medicine since the Eastern Jin Dynasty. as well as all essential amino acids.
- Nostoc carneum
- Nostoc comminutum
- Nostoc commune (Linnaeus) Vaucher ex Bornet et Flahault
- Nostoc ellipsosporum
- Nostoc flagelliforme
- Nostoc linckia
- Nostoc longstaffi
- Nostoc microscopicum (Carmichael ex Harvey) Bornet et Flahault