''Dulichium'' is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus of

sedge The Cyperaceae () are a family of graminoid (grass-like), monocotyledonous flowering plants known as wikt:sedge, sedges. The family (biology), family is large; botanists have species description, described some 5,500 known species in about 90 ...

containing the single species ''Dulichium arundinaceum'', which is known by the common name threeway sedge. This is an

aquatic Aquatic means relating to water; living in or near water or taking place in water; does not include groundwater, as "aquatic" implies an environment where plants and animals live. Aquatic(s) may also refer to: * Aquatic animal, either vertebrate ...

or semi-aquatic plant of the lakes, streams, and ponds of the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

and

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

. It has a wide distribution across the two countries, though noticeably absent from the

Dakotas The Dakotas, also known as simply Dakota, is a collective term for the U.S. states of North Dakota and South Dakota. It has been used historically to describe the Dakota Territory, and is still used for the collective heritage, culture, geo ...

and from the Southwestern Deserts. ''Dulichium arundinaceum'' has a thick

rhizome In botany and dendrology, a rhizome ( ) is a modified subterranean plant stem that sends out roots and Shoot (botany), shoots from its Node (botany), nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from ...

system and grows to heights approaching a meter. It is reminiscent of

bamboo Bamboos are a diverse group of mostly evergreen perennial plant, perennial flowering plants making up the subfamily (biology), subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family, in th ...

in appearance when new, growing bright green erect stalks in large, grassy stands. Stems are round to slightly triangular in cross-section (though not nearly as angularly triangular as in ''Cyperus'' or ''Carex''), and hollow. The leaves are in three ranks along the stem when seen from above (thus the common name "threeway sedge"), with sheaths along the stems, and the

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

grows from the leaf axilla. The spikelets are generally lance-shaped and one to three centimeters long when ripe. Two varieties are recognized: *''Dulichium arundinaceum'' var. ''arundinaceum'' - most of species range including Québec *''Dulichium arundinaceum'' var. ''boreale'' Lepage - Québec

Fossil record

One

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...

of †''Dulichium marginatum'' has been described from a

middle Miocene The Middle Miocene is a sub-epoch of the Miocene epoch (geology), epoch made up of two Stage (stratigraphy), stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene. The sub-epoch lasted from 15.97 ± 0. ...

stratum In geology and related fields, a stratum (: strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ...

of the Fasterholt area near

Silkeborg Silkeborg () is a Denmark, Danish town with a population of 52,571 (1 January 2025).Jutland Jutland (; , ''Jyske Halvø'' or ''Cimbriske Halvø''; , ''Kimbrische Halbinsel'' or ''Jütische Halbinsel'') is a peninsula of Northern Europe that forms the continental portion of Denmark and part of northern Germany (Schleswig-Holstein). It ...

Denmark Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...

.Angiosperm Fruits and Seeds from the Middle Miocene of Jutland (Denmark) by

Else Marie Friis Else Marie Friis (born 18 June 1947) is a Danish botanist and paleontologist. She is Professor Emerita in the Department of Geoscience at Aarhus University. Her work has been fundamental in the phylogenetic analysis of angiosperms, with widesprea ...

, The Royal Danish Academy of Sciences and Letters 24:3, 1985

References

External links

Jepson Manual Treatment
*

* * Cyperaceae Plants described in 1753 Taxa named by Carl Linnaeus Freshwater plants {{Cyperaceae-stub