Araceae, Subfamily Aroideae Common Name:
Water Lettuce [includes "Dwarf" Watter Lettuce] Origin and Habitat:
Unknown origin, but likely in the Tethys region which may be considered what today is East Africa, India, Indonesia back when these were connected. Pantropical today, this plant is found world-wide in tropical and subtropical regions. It occurs in freshwater and sometimes even in brackish. Ideal Position in the Aquarium:
Strictly floating. An ideal pond plant. Lighting Requirements
Moderate to bright. Growth rate and size is partly dependent upon light. Growth Rate:
Rapid Minimum Tank Size
Variable. In good conditions, this plant will grow large, up to 50cm / 20 inches across, though usually smaller. Growth depends upon conditions. The so-called "Dwarf" Water Lettuce is not a distinct species but simply due to less-than-ideal conditions of light and nutrients. Water Parameters
Soft to fairly hard (up to 25 dGH), acidic to basic (pH 6 to 8), temperature 15-30C/60-86F. Description
A magnificent floating plant that is best suited to an outdoor pond or large aquarium. The "dwarf" form, which is not a separate variety, subspecies or distinct species, is believed by most sources to be due to less than ideal conditions; observations have noted that the "dwarf" plants develop into normal large plants when conditions improve.
The rapid growth of this plant makes it a good plant in new tanks, since it has an enormous appetite for nutrients including ammonia/ammonium. It also provides excellent cover for fry.
The oldest fossils representing the Pistia
clade date from the Middle Eocene epoch, 48.6 to 37.2 million years ago. Pistia
itself is first known from seeds from the Late Oligocene/Early Miocene and mid-Miocene periods of Europe and Russia, up to 33 million years ago (Renner & Zhang, 2003).
The Araceae is a family of flowering plants in which the flower is borne on an inflorescence known as a spadix which is usually partially enveloped by a leaf-like bract called a spathe. Also known as the Arum family, there are more than 3700 species in 107 genera; most occur in the Neotropics, but there are several species in the Old World tropics and the northern temperate regions. The Aroideae is the largest subfamily, holding about 72 different genera, including Anubias
of interest to aquarists.
The species was described by Carl Linnaeus (1707-1778), the Swedish scientist who developed the consistent use of binomial names for both plants and animals that we use today to classify all life, and who himself validly published over 9,000 plant names. Linnaeus erected the genus Pistia
, the name derived from the Greek pistos
, meaning watery, which contains just this single species. The species epithet stratiotes
is Latin and means reminiscent of the Stratiotes
genus of submerged aquatic plants. References:
Kasselmann, Christel (2003), Aquarium Plants
, English edition, Krieger Publishing Company, 2003.
Renner, Susanne S. and Li-Bing Zhang (2003), "Biogeography of the Pistia
Clade (Araceae): Based on Chloroplast and Mitochondrial DNA Sequences and Bayesian Divergence Time Inference," Systematic Biology
, Volume 53, Issue 3, pp. 422-432. Contributing Members
The following members have contributed to this profile: Byron