Schoenoplectus lacustris
- Overview
- Images
- Identify
- Biology
- Taxonomy
- Occurrence
- Specimen

Growing form
Perennial herb, which forms extensive stands.
Size
1–3 m high.
Stem
The stem is dark green, mostly afoliate, terete, smooth, rigid, 0.5–1 cm thick and with spongy continuous pith. The rhizome is horizontal and robust.
Leaf
The leaves are at the base of the stem. The leaves are sheathed, typically without a lamina or with a short lamina. (In flowing water the lamina can be long and flat). The sheaths are yellowish brown or maroon. The lowest bract of the inflorescence is like an extension to the stem. The bract is as long as the inflorescence or often longer.
Flower
The branches inflorescence is at the summit of a stem. It consists of 15–25 spikes. The primary branches of the inflorescence are typically more than 3 cm long. The spikes are 5–12 mm long and arranged individually or in clusters of few. The bisexual flowers are at the axils of scales. The scales are brown, smooth and lustrous. There are three stamens and a gynoecium with three stigmas in a flower.
Fruit and seed
The fruit is an obtusely triangular achene (2.5–3 mm).

The map represents observations of this taxon, but it may not be used as a distribution map.
- Total squares
- järvikaisla (Finnish)
- säv (Swedish)
- 2019
- 2010
- Pertti Uotila
- Heikki Toivonen
- Vascular plants
- Plant life forms
- Aquatic plants
- Helophytes