Lemna trisulca aka Ivy Leaved Duckweed

Lemna trisulca is a small water plant in the Araceae family. Its common names include ivy-leaved duckweed and star duckweed. Kew lists its native range as worldwide and its climate as temperate. The RHS confirms that it is native to Britain and Ireland. Records also place it across Asia and North America. It grows in ponds, ditches, and other quiet waters. Its wild sites include cool regions with calcium-rich water.

Plants For A Future describes this species as a perennial. In temperate areas, it survives winter through resting buds. These sink to the pond floor in late autumn. They rise again when spring returns. The plant spreads fast by division once it reaches a pond. This means it needs little help to make more plants. The supplied sources give no mature height or spread. They also give no details of its leaves or fruit.

Its flowers appear from May to July, according to Plants For A Future. Each plant can carry both male and female flowers. The source lists USDA hardiness zones 4–8 and reports frost tolerance. For growing, it calls for sun and still water. The water should contain plenty of nitrates and lime. It lists neutral to mildly alkaline conditions as suitable. It also states that this species cannot grow in shade. These needs make water conditions central to its care.

This duckweed has value for pond wildlife and cold-water aquaria. Fish and birds can use the growing plant as food. It also gives pond creatures cover. Its fast spread can make it a nuisance in ponds. Plants For A Future suggests removing excess growth with a scoop. The removed plants can go onto a compost heap. The same source warns that it may carry fish parasites. This matters when using it in an aquarium with fish.

Plants For A Future records no known edible uses. It also lists no known hazards for this species. That does not establish it as a food plant. The source gives it a low medicinal-use rating. It records a past use in a wet poultice. That treatment mixed this duckweed with another plant for swellings. This is a record of use, not proof of benefit.