Branch points are bifurcations of roughly equal size
5. Does the material possess any of the following special features?
-
Filaments composed of regular cells occasionally interrupted by specialised cells (heterocytes) with thickened walls, that are often larger; branches may be more than one cell wide; chloroplasts and other organelles inside cells are not found (although granules may exist)
Stigonema -
Branches formed at angled bends in the middle of a cell
Microthamnion -
Branches anastomose to form a net
Hydrodictyon -
Cross walls are absent; filament is a large siphon containing numerous small discoidal yellow-green chloroplasts; branches may be rare
Vaucheria -
Long hair cells are present; cell division scars can be seen on the walls of some cells
Bulbochaete -
Branches repeatedly divide in a tree-like manner; cross walls are present; hair cells are absent
