Limnobium

Scientific name

Limnobium Rich.

Common names

Amazon frogbit, American frogbit

Family

Hydrocharitaceae

Similar genera

Eichhornia, Heteranthera, Hydrocharis, Hydrocleys, Limnocharis

Native distribution

America

Species cultivated

Limnobium laevigatum (Humb. & Bonpl. ex Willd.) Heine

L. spongia (Bosc) Steud.

Adventive distribution

Limnobium laevigatum is introduced into various parts of United States.

Weed status

Sometimes troublesome; both Limnobium species are considered weeds in a few countries.

Habit

free-floating, stoloniferous rosetterosette:
(n) a radiating cluster of leaves, usually close to the ground at the base of a plant
plant

Brief description

Perennialperennial:
(adj) (of a plant) having a life cycle of more than two years
, monoeciousmonoecious:
(adj) having separate male and female flowers on the same individual
. Leaves floating or emergentemergent:
(adj) (syn. emersed) with parts raised out of the water; extending up out of the water
, arranged in basalbasal:
(adj) at or pertaining to the base, or point of attachment
rosettes along stolons; petiolepetiole:
(n) the stalk of a leaf
short or elongate; leaf bladeblade:
(n) (syn. lamina) the flat, expanded part of a leaf, frond, or petal (excluding, e.g., the petiole)
orbicularorbicular:
(adj) circular in outline
-obovate to reniformreniform:
(adj) kidney-shaped
, venationvenation:
(n) the arrangement of veins in a leaf
palmate, inconspicuous; base cordatecordate:
(adj) heart-shaped; in the form of two rounded lobes
to rounded; marginmargin:
(n) edge; rim
entireentire:
(adj) having a continuous margin that is not toothed or lobed
; aerenchymaaerenchyma:
(n) plant tissue with large, gas-filled intercellular spaces that facilitates gaseous exchange and maintains buoyancy
on abaxialabaxial:
(adj) the side facing away from the axis, as in the underside of a leaf
surface distinct; basalbasal:
(adj) at or pertaining to the base, or point of attachment
sheath present. Flowers unisexualunisexual:
(adj) (of a flower) with either stamens (male) or pistils (female) but not both; consisting of only male or female flowers
, pedicelspedicel:
(n) the stalk of a single flower in an inflorescence, or of a grass spikelet
short, spathespathe:
(n) a large bract or bracts subtending and often enclosing an inflorescence
of 1 or 2 free bracts; female flowers 1 to 3, hypanthiumhypanthium:
(n) the cup-shaped structure formed from the fusion of the basal parts of the calyx, corolla, and stamens, on the rim of which these parts arise
absent; males in cymes of up to 11 flowers; sepals 3; petals 3, rudimentary or absent in female flowers. Dispersal by seed and stem fragments.

Natural habitat

still waters of lakes, rivers, ponds, and swamps

Additional comments

Limnobium contains only two species, with L. laevigatum being more commonly cultivated for ponds and aquaria. Limnobium spongia is more likely to form emergentemergent:
(adj) (syn. emersed) with parts raised out of the water; extending up out of the water
leaves than L. laevigatum, which produces emergentemergent:
(adj) (syn. emersed) with parts raised out of the water; extending up out of the water
leaves only when it becomes crowded. Both are highly variable species; leaf shape is important in differentiating the them: L. laevigatum has a more rounded leaf apexapex:
(n) the point farthest from the point of attachment; the tip (often pointed)
, a shallower basalbasal:
(adj) at or pertaining to the base, or point of attachment
notch, little or no red pigment, and shorter stolons (plants more crowded) than L. spongia. The spongy aerenchymaaerenchyma:
(n) plant tissue with large, gas-filled intercellular spaces that facilitates gaseous exchange and maintains buoyancy
cells are most prominent on young floating leaves. Older plants and aerial leaves of both species have reduced aerenchymaaerenchyma:
(n) plant tissue with large, gas-filled intercellular spaces that facilitates gaseous exchange and maintains buoyancy
.