Taxonomy

Aegagropila linnaei Kützing 1843 (= Cladophora aegagropila (Linnaeus) Rabenhorst).

Plants of dense and often dark green

Irregularly branched filamentous, one to several branches arise from a cell in a subterminal position, sometimes in an irregular series or oppositely arranged
Adventitious rhizoids arise from basal pole of cell and
- attach to or intertwine around the branches
- attach to the substratum, often coralloid in unattached forms
Cells generally
- cylindrical, more often
- club-shaped towards base,
- lateral branches up to 200 µm wide and cells to
- 15 times longer than wide,
- very thick-walled (up to 20 µm thick)
- Apical cells 30–70 µm wide and up to 25 times longer than broad

Cells aggregate to form

Coarse carpet or cushion-like growth more commonly occur in rivers compared to the loose-lying mats or ball-like growths that are frequently more abundant in lakes
Lake balls are from 1.5 cm to about 30 cm in diameter and the larger ones are hollow since the central filaments decay as the ball increases in size.
- These balls have been known as ‘Cladophora balls’ but recent molecular studies have meant the transfer of Cladophora aegagropila back into the genus Aegagropila