''Nostoc commune'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of cyanobacterium in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Nostocaceae. Common names include star jelly, witch's butter, mare's eggs. It is the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

of the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

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 ...

'' and is cosmopolitan in distribution.

Description

''Nostoc commune'' is a colonial species of cyanobacterium. It initially forms a small, hollow gelatinous globule which grows and becomes leathery, flattened and convoluted, forming a gelatinous mass with other colonies growing nearby. Inside the thin sheath are numerous unbranched hair-like structures called

trichome Trichomes (; ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant ...

s formed of short cells in a string. The cells are bacteria and thus have no nucleus nor internal membrane system. To multiply, they form two new cells when they divide by

binary fission Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two values (0 and 1) for each digit * Binary function, a function that takes two arguments * Binary operation, a mathematical o ...

. Along the trichomes, larger specialist nitrogen-fixing cells called heterocysts occur between the ordinary cells. When wet, ''Nostoc commune'' is bluish-green, olive green or brown but in dry conditions it becomes an inconspicuous, crisp brownish mat.

Distribution and habitat

''Nostoc commune'' is found in many countries around the world. It is able to survive in extreme conditions in polar regions and arid areas. It is a terrestrial or freshwater species and forms loose clumps on soil, gravel and paved surfaces, among mosses and between cobbles. In Singapore, ''Nostoc commune'' is found growing on alkaline soils, in

brackish water Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuary ...

, in paddy fields, on cliffs and on wet rocks.

Biology

''Nostoc commune'' can fix nitrogen from the atmosphere and can therefore live in locations where no nitrogenous compounds are available from the substrate. ''Nostoc commune'' contains

photosynthetic Photosynthesis ( ) is a Biological system, system of biological processes by which Photoautotrophism, photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical ener ...

pigments and the energy storing photosystems in membrane structures called thylakoids located in cytoplasm of the cells. It also contains pigments that absorb long and medium wavelength

ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...

radiation, which enables it to survive in places with high levels of radiation. Under adverse conditions, ''Nostoc commune'' can remain dormant for an extended period of time and revive when conditions improve and water becomes available. The desiccated colony is resistant to heat and to repeated patterns of freezing and thawing and produces no oxygen while dormant. It has been found that extracellular polysaccharides are vital to its stress tolerance and ability to recover. ''Nostoc commune'' can occur in pockets in the thallus of hornworts such as '' Phaeoceros''.

Uses

''Nostoc commune'' is eaten as a salad in the Philippines and is also eaten in Indonesia, Japan and China. In Taiwan, it is nicknamed ''yǔ lái gū'' (meaning "post-rain mushroom"). Research indicates that consumption of ''Nostoc commune'' var. ''sphaeroides'', in addition to consumption of other cyanobacteria, may be beneficial by means of an anti-inflammatory mechanism. The related '' Nostoc flagelliforme'', sometimes named as a variety of this species, is known as ''fàcài'' in China. It forms part of the food traditionally served at the

Lunar New Year Lunar New Year is the beginning of a new year based on lunar calendars or, informally, lunisolar calendars. Lunar calendar years begin with a new moon and have a fixed number of lunar months, usually twelve, in contrast to lunisolar calendar ye ...

References

{{Authority control Nostocaceae Bacteria described in 1753 Taxa named by Carl Linnaeus