Tetradesmus lagerheimii is a green alga in the family Scenedesmaceae.

[1] Tetradesmus lagerheimii forms colonies of two, four or eight cells in a single row, with cells arranged linearly or in a somewhat zig-zag fashion.

The colony is typically curved, semicircular, or contorted.

Cells are spindle-shaped, arc-like, or sigmoid, 9.2–34.5(–40) μm long and 2–5.5 μm wide; the outermost side is concave; both ends taper to a point.

[2] It is a very common species, and is found in a variety of freshwater habitats.