''Nostoc pruniforme'' (Mare's eggs) are a species of

cyanobacterium Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blu ...

. These freshwater

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

grow in

colonies In modern parlance, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the '' metropolitan state'' ...

which take the form of dark green, gelatinous spheres with a smooth surface like a plum. It is common and widely distributed both geographically and ecologically in oligotrophic and mesotrophic freshwaters in temperate and sub-Arctic regions. In temperate lakes, ''N. pruniforme'' appears to grow in diameter from ∼0·2 cm in late spring to 2–3 cm in midsummer and it can rapidly die off, supposedly because of attacks by viruses or bacteria at high summer temperatures (K. Sand-Jensen, unpubl. data). In contrast, in a cold (4 °C), nutrient-poor spring in Oregon, USA, ''N. pruniforme'' reached a handball size of 15–17 cm in diameter and weighed 2.6 kg after sustained slow growth for 9–14 years. Very large colonies are also found in cold transparent lakes in Greenland (K. Sand-Jensen, unpubl. data). In addition to their larger size and persistence, they differ from Danish temperate specimens by having a more solid surface and a denser gel.

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External links

Nostoc pruniforme
on Algaebase Nostocaceae {{cyanobacteria-stub