Soil Algae



Notes from 2012:  
I have not been on many collecting trips lately, but some unusual algae have put in an appearance very close to home. The very wet weather this year has probably played a part in this.

The first to come to my notice was in the mud in a drained temporary pond: numerous little green globes a bit smaller than a peppercorn. These were Botrydium, a Xanthophyte. The plant is siphonaceous (coenocytic), having numerous nuclei in each cell. The bulbous part is attached to branching rhizoids which are buried in the mud.

Drying mud with clusters of Botrydium plants

Botrydium viewed under a dissecting microscope: the pinhead is approximately 3mm across
A single plant with rhizoids

Later in the season, an unusual dark red growth appeared on the surface of the soil in the greenhouse. This turned out to be Porphyridium, a Rhodophyte. It also appears to form globular structures, but they do not have the firm consistency of the Botrydium. The individual cells are easily released from the colonial mucilage

Porphyridium under a dissecting microscope: it forms a film over the surface of the soil and is not easily removed from it.
Individual cells of Porphyridium

Other soil algae from Shewington: (2010) This one forms a felty mass on the soil which looks very much like moss.

Vaucheria: has multinucleate cells forming branching filaments
A siphonaceous Xanthophyte which reproduces sexually: these are the reproductive structures
This image shows a maturing oogonium


John Kinross