Hydrodictyon, although quite different in form and growth habit from Pediastrum, is similar with regard to its life history.  The sexual life history is haplontic and isogamous (note d-l for gamete release and zygote formation).  The same cells that released gametes can release zoospores (d-p).  The meoitic spores (meiospores) function as the zoospore and produce q, a cell that undergoes autocolony formation (also illustrated d-i).  There is no vegetative reproduction in this organism.