''Heteranthera limosa'' is an annual flowering plant in the water hyacinth family known by the common names ducksalad and blue mudplantain. It grows in shallow water or on mud. It is considered a threatened species in parts of the central United States, and an

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...

weed in California, where it is a nuisance in rice paddies. It is also occasional in Florida waterways.

Description

''Heteranthera limosa'' is a polymorphic annual growing 2 to 6 inches tall. It looks different depending on the type of habitat it is growing in; plants in water look different than those growing on muddy ground. It is easily confused with other closely related species, so reliable identification is based on flowering plants. It has thick, spade-shaped green leaves with parallel veins. When plants are grown in water the leaves may be above or below the water surface, with submerged leaves linear in shape. The branching stems are creeping and maybe as long as 15 inches, rooting at the nodes. Its blue, purple, or white, perfect flowers, are six- merouse with narrow petals and three stamens. The nearly 1 inch wide flowers are subtended by a

spathe In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of ...

. The flowering period is very brief subject to the correct environmental conditions, and can occur from May to November. The flowers open early in the morning and wither by noon.

Distribution and habitat

''Heteranthera limosa'' grows in shallow water with the best growth in water that is less than 5cm deep; it is also found immersed at pond edges and in roadside ditches. It is found growing in Arizona, Arkansas, California, Colorado, Florida, Illinois, Iowa, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Nebraska, New Mexico, Oklahoma, South Dakota, Tennessee, Texas, Mexico, West Indies, Central America, and South America (Argentina, Bolivia, Brazil, Colombia, Ecuador, Paraguay, Venezuela). In Minnesota this species is at the northern limit of its natural distribution where it is found in the southwestern corner of the state, it occurs in shallow vernal pools that form from water that seeps between rock layers that includes

Sioux quartzite The Sioux Quartzite is a Proterozoic quartzite that is found in the region around the intersection of Minnesota, South Dakota, and Iowa, and correlates with other rock units throughout the upper midwestern and southwestern United States. It was ...

; it is found in association with other rare species in the state such as ''

Isoetes melanopoda ''Isoetes melanopoda'' is a species of nonflowering vascular plant belonging to the quillworts in the family Isoetaceae. Its common names include: black-footed quillwort, midland quillwort, and prairie quillwort. Description ''Isoetes melanopoda' ...

'', ''

Plantago elongata ''Plantago elongata'' is a species of plantain known by the common names prairie plantain and slender plantain. It is native to much of western North America, from British Columbia to California and as far east as Minnesota. It grows in wet ha ...

'', and ''

Cyperus acuminatus ''Cyperus acuminatus'' is a common species of sedge known by several common names, including tapertip flatsedge and pale umbrella-sedge. This plant is native to North America, where it is widespread across the Great Plains and the western United ...

''. In Minnesota it is listed as a threatened species, where it is rare and limited to specific unusual microhabitats.

References

External links

Ducksalad as Aquatic Weed

Jepson Manual Treatment
Pontederiaceae Freshwater plants Flora of the United States Invasive plant species in Japan {{Commelinales-stub