Nostoc sp. (genus)

A cyanobacterium at Acton, ACT

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Identification history

Nostoc sp. (genus)

6 Jul 2016

Heino

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2 comments

Heino wrote:

6 Jul 2016

The species of the genus Nostoc are cyanobacteria and, as well as photosynthesizing, they fix atmospheric nitrogen (as do the non-Nostoc root symbionts of wattles and peas). Nostoc has a gelatinous texture, very much like fungi in the genus Tremella (e.g. http://canberranaturemap.org/Community/Sightings/Details/3344077 and http://canberranaturemap.org/Community/Sightings/Details/3343733). Nostoc appears in shades of green-khaki-brown, sometimes fairly dark. Clearly there is no way you'd confuse Nostoc with those two species of Tremella but there are also brown to black species of gelatinous fungi with a superficial resemblance to Nostoc. However, the fungi grow attached to wood while Nostoc grows unattached and those shown here were loose on soil or on the moss mat. Nostoc is translucent, as you can see in photo 3 (where the broad lines form a centimetre grid). When dry Nostoc shrivels to become very thin, black and brittle, but water quickly swells it. These specimens were photographed at the Australian National Botanic Gardens where, as an honorary associate, I have permission to collect cryptogams.

Heino wrote:

14 Jul 2016

Photo 4 shows the same subject as Photo 3, but now dry. I show virtually the same number of background grid points in each photo, so you can immediately see how much this specimen of Nostoc has shrunk on drying.

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