Pistia stratiotes: Water Lettuce
An attractive paludarium must include plants that float on the water’s surface. Mention has already been made of Eichhornia crassipes, but the selection is much larger, as you will find by going to a specialist supplier.
If you are setting up a small paludarium in a warm, well-lit to sunny spot, then you should not fail to include the small floating aquatic Pistia stratiotes, whose lovely pale green foliage will be a permanent decorative element in the pool. The only member of the genus, it is found throughout the tropical regions of the world, though its native land is tropical America, where it grows chiefly in lowland country (even in slightly brackish water where rivers flow into the sea and form quiet, peaceful lagoons); very occasionally it is found farther south as high up as 1,000 m (3,300 ft) above sea level.
To give one an idea of a natural grouping of plants for a paludarium, listed here are plants that grow together in the wild in the El Farallon Lagoon near Nautla in the state of Veracruz, Mexico: Cypenis articularis, C. ligularis, Ludwigia sp.,am-pla, Typha dominguensis and Pistia stratiotes.
Naturally other species of the various genera may be used in their stead. Such pools, containing a grouping copied from the wild, are very pretty and natural-looking and furthermore they soon establish a symphathetic balance.
Pistia forms floating rosettes of soft, pale green leaves about 10 to 15 cm (4 to 6 in) wide. The inflorescence is greatly reduced: a whitish hairy spathe encloses a single male and a single female flower, the whole measuring less than 1 cm (½ in).