''Dulichium'' is a
monotypic genus of
sedge containing the single species ''Dulichium arundinaceum'', which is known by the common name threeway sedge. This is an
aquatic or semi-aquatic plant of the lakes, streams, and ponds of the
United States and
Canada It has a wide distribution across the two countries, though noticeably absent from the
Dakotas
The Dakotas 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, geography, fauna, sociology, econom ...
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 shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...
system and grows to heights approaching a meter. It is reminiscent of
bamboo 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 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 fruit of †''Dulichium marginatum'' has been described from a middle Miocene
The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene.
The sub-epoch lasted from 15.97 ± 0.05 Ma to 11.608 ± 0.005 Ma (million y ...
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 ei ...
of the Fasterholt area near Silkeborg in Central Jutland, Denmark.[Angiosperm Fruits and Seeds from the Middle Miocene of Jutland (Denmark) by Else Marie Friis, The Royal Danish Academy of Sciences and Letters 24:3, 1985]
References
External links
Jepson Manual Treatment
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*
*
Cyperaceae
Plants described in 1753
Taxa named by Carl Linnaeus
Freshwater plants
{{Cyperaceae-stub