Lemnoideae

Lemnoideae

Duckweeds floating on water

Lemnoideae, commonly known as duckweeds, are a subfamily of flowering aquatic plants within the family Araceae. These small, free-floating plants are found on the surface of still or slow-moving bodies of fresh water across the globe. They are among the smallest and simplest of flowering plants, often forming dense mats on the water surface.

Description

Diagram of Lemnoideae systematics and biology

Lemnoideae are characterized by their small, simple structure. They lack stems and leaves in the traditional sense, instead having a thallus-like body that floats on the water surface. The thallus is often oval or round, and the plants reproduce primarily through vegetative budding. Some species can also produce flowers, although this is rare.

The root system of Lemnoideae is minimal, with some species having no roots at all, while others have a single root or a few roots that hang down into the water. These roots help stabilize the plant and absorb nutrients from the water.

Ecology

Close-up of duckweeds

Lemnoideae play a crucial role in aquatic ecosystems. They provide food and habitat for a variety of aquatic organisms, including fish, insects, and birds. The dense mats formed by duckweeds can also help reduce algal blooms by blocking sunlight and absorbing excess nutrients from the water.

These plants are highly efficient at nutrient uptake, making them useful for bioremediation in polluted water bodies. They can absorb heavy metals and other pollutants, helping to clean the water.

Reproduction

Lemna minor, a common species of duckweed

Reproduction in Lemnoideae is primarily asexual, occurring through vegetative budding. New plants form as buds on the parent plant, eventually breaking off to become independent. This rapid form of reproduction allows duckweeds to quickly colonize new areas.

Although rare, sexual reproduction can occur in some species. Flowers are small and inconspicuous, with a single pistil and one or two stamens. Pollination is typically by water or wind.

Distribution

Lemna trisulca, another species of duckweed

Lemnoideae are found worldwide, with the exception of extremely cold regions. They thrive in a variety of freshwater habitats, including ponds, lakes, marshes, and slow-moving streams. Their ability to rapidly reproduce and adapt to different conditions makes them highly successful colonizers.

Uses

Lemna gibba, known for its gibbous shape

Duckweeds have several practical applications. They are used in wastewater treatment due to their ability to absorb nutrients and pollutants. In agriculture, they serve as a high-protein feed for livestock and fish. Additionally, duckweeds are being researched for their potential in biofuel production, as they have a high starch content that can be converted into ethanol.

Species

Spirodela polyrrhiza, a larger species of duckweed

The subfamily Lemnoideae includes several genera, such as Lemna, Spirodela, Wolffia, and Wolffiella. Each genus contains multiple species, varying in size, shape, and habitat preference.

Related pages

• Aquatic plant
• Bioremediation
• Araceae

Gallery

• 

  Duckweed-covered water with bald cypress trees

• 

  Aerial view of a duckweed-covered lake

• 

  Duckweed-covered pond in Poland