British distribution: Widespread and common in freshwater.
Draparnaldia mutabilis is a widespread alga of unpolluted freshwaters, often those that are low in nutrients. It is attached to stones or aquatic macrophytes. There is a well defined main axis, with more slender side branches, these again branched, and with the fine branches ending in long cells that taper to the apices. The chloroplasts are parietal, i.e. wrapped around the inside of the cell wall. Those of the cells of the main axis are distinctively subdivided into narrow ribbons in this species.
John (in John et al., 2002) recognises two British species, both widespread, but points out that they might well be states of a single species, the differences apparently controlled by the nutrient status of the water and not retained in culture. Whereas Draparnaldia mutabilis is identified by its primary branches themselves becoming long, clear axes that extend beyond their own side-branches, D. glomerata has its side branches branching to form more or less orbicular tufts.
Asexual reproduction is by production of biflagellate zöospores and by thick-walled non-motile spores. The motile gametes are quadriflagellate. Zöospore release was not noted during examination of the material, and the photographed material was from a wild collection containing other organisms. However, zöospores may well be visible in the photographs.
Photographed material: from nutrient-poor water adjacent to a peat-bog on Gleniffer Braes, Renfrewshire, April 2001.