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