Elodea and Egeria
These are known as water pests, on account of their tendency to proliferate.
Under an intense light they produce a great deal of oxygen. They put down roots
but can also live afloat, preferably in hard, alkaline water.
Originally from North America, Canadian pond weed has been introduced into temperate
regions all over the world, although only the female has been present in Europe
since the middle of the 19th century, and it can obviously only reproduce through
cuttings. It is a plant for temperate aquariums or garden ponds, with an optimum
temperature range of 15-20°C.
Egeria densa (formerly Elodea densa)
Both sexes of the dense elodea were, similarly, introduced into Europe, although
it is highly unusual to find reproduction through flowering in an aquarium. It is
suited to temperate aquariums, but can tolerate temperatures of up to 25°C. Size: