''Limnobium laevigatum'' is a floating aquatic plant, and is a member of the family

Hydrocharitaceae Hydrocharitaceae is a flowering plant family including 16 known genera with a total of ca 135 known species (Christenhusz & Byng 2016), that including a number of species of aquatic plant, for instance the tape-grasses, the well known Canadia ...

. Common names include West Indian spongeplant, South American spongeplant and Amazon or smooth frogbit. This plant was introduced to North American waterways through use in

aquarium An aquarium (plural: ''aquariums'' or ''aquaria'') is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aq ...

s and aquascapes.

Plant origin and distribution

Spongeplant originates from fresh water habitats of tropical and subtropical Central and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

. In

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

it has been introduced as an ornamental pond plant, and has escaped into greater waterways including areas surrounding Redding and Arcata, the

Sacramento river The Sacramento River ( es, Río Sacramento) is the principal river of Northern California in the United States and is the largest river in California. Rising in the Klamath Mountains, the river flows south for before reaching the Sacramento� ...

delta and the

San Joaquin River The San Joaquin River (; es, Río San Joaquín) is the longest river of Central California. The long river starts in the high Sierra Nevada, and flows through the rich agricultural region of the northern San Joaquin Valley before reaching Suis ...

, and ponds and irrigation canals.

Description

''Limnobium laevigatum'' is a floating aquatic plant, which can be mistaken for water hyacinth ('' Eichornia crassipes'') due to their superficial similarity. Juvenile plants grow in rosettes of floating leaves that lie prostrate upon the water surface, a distinguishing character of the juvenile plant is the presence of spongy aerenchyma tissue upon the abaxial surface (underside) of the leaf. Mature plants grow up to 50 cm tall, and have emergent leaves borne on petioles that are not swollen or inflated like the spongy leaf stalks of water hyacinth, which aid in buoyancy. Spongeplant produces stolons which bear gametes. Flowers are small, white, and unisexual. Female flowers have an inferior ovary, the fruit is a fleshy capsule 4–13 mm long and 2–5 mm in diameter, and seeds are 1 mm long, ellipsoid, and hairy. ''Limnobium laevigatum'', or Smooth Frogbit can be distinguished from ''

Limnobium spongia ''Limnobium'', common names spongeplant and American frogbit, is a group of aquatic plants in the Hydrocharitaceae described as a genus in 1814. It is widespread in freshwater environments in Latin America, the West Indies, and the United State ...

'', American frogbit, by flower and leaf characteristics as well as range. The flowers of both species vary greatly over their ranges. American frogbit is not known to occur in western states unlike smooth frogbit. American frogbit in general has more

cordate Cordate is an adjective meaning ' heart-shaped' and is most typically used for: * Cordate (leaf shape) The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a ...

-based floating leaves, while smooth frogbit generally has more

spatulate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular ...

floating leaves.

Plant reproduction

''Limnobium laevigatum'' can reproduce and distribute sexually through flower pollination and seed production, and also

vegetatively Vegetative reproduction (also known as vegetative propagation, vegetative multiplication or cloning) is any form of asexual reproduction occurring in plants in which a new plant grows from a fragment or cutting of the parent plant or spec ...

through fragmentation of stolon segments. The juvenile plants have a great capacity for distribution in that they are small, they float and can be easily and quickly carried along by water currents.

Aquascape use

Amazon Frogbit in captivity has two hazards to its health which aquarium owners can avoid: (1) water droplets on the tops of the leaves can rot the plant (they must be kept dry), and (2) some species of aquatic snail appear to like to eat the spongy material on the bottoms of the plant leaves (keep them near the center of the tank, not against the glass on the edges.)

Limnobium Management

California Department of Food and Agriculture The California Department of Food and Agriculture (CDFA) is a cabinet-level agency in the government of California. Established in 1919 by the California State Legislature and signed into law by Governor William Stephens, the Department of Food ...

(CDFA) crews which already manage other invasive aquatic plants including ''

Hydrilla verticillata ''Hydrilla'' (waterthyme) is a genus of aquatic plant, usually treated as containing just one species, ''Hydrilla verticillata'', though some botanists divide it into several species. It is native to the cool and warm waters of the Old World in ...

'' and ''

Eichhornia crassipes ''Pontederia crassipes'' (formerly ''Eichhornia crassipes''), commonly known as common water hyacinth is an aquatic plant native to South America, naturalized throughout the world, and often invasive outside its native range.Hydrocharitaceae Aquatic plants Taxa named by Aimé Bonpland Taxa named by Alexander von Humboldt