Description
''Schoenoplectus lacustris'' grows up to tall, with stems thick. Most of the leaves of ''S. lacustris'' are reduced to bladeless sheaths around the stem, but leaf blades up to long can be formed under water. The inflorescence appears at the top of the stem, and comprises 3–10 branches, each of which is up to long and may be again divided into shorter branches. The flowers are in the form of spikelets, each of which is long by wide. The stems of ''S. lacustris'' are round in cross-section, in contrast to the triquetrous (rounded-triangular) stems of other species in the genus, such as '' S. triqueter'' and '' S. pungens''. The stems of '' S. tabernaemontani'' are also round, but ''S. tabernaemontani'' is a smaller plant, less than tall, with only two stigmas per flower.Distribution
''Schoenoplectus lacustris'' is widespread in Europe, albeit rare in the far north, and extends eastwards into Asia as far as Mongolia. It is also found in a number of Mediterranean sites in North Africa, and has been introduced to Haiti.Taxonomy
The species was first described by Carl Linnaeus as "''Scirpus lacustris''" in his 1753 '. It became part of the genus '' Schoenoplectus'' when Eduard Palla raised this from the rank of subgenus to the rank of genus in 1888. Two subspecies are recognised; the autonymic subspecies (''S. lacustris'' subsp. ''lacustris'') is found throughout the range of the species, and a second, ''S. lacustris'' subsp. ''hippolyti'' is restricted to an area reaching from the Caucasus to the mountains of Central Asia.References
{{Taxonbar, from=Q158956 lacustris Plants described in 1753 Flora of Europe Taxa named by Carl Linnaeus Taxa named by Eduard Palla