Wetland and Aquatic Plants
of
Oklahoma
Interactive Keys: Emergent
Grasslike
Sedges (Cyperaceae)
4. Flatsedges or umbrella sedges (Cyperus spp.)
a. Seeds (achenes) round; flowers two stigmas
b. Seeds (achenes) three angles; flowers with three
stigmas
i. spikelets in dense heads
ii. spikelets not in dense heads, inflorescence
long and string-like
Seeds
(achenes) round and lense shaped (lenticular); flowers with two stigmas
Yellow
flatsedge (Cyperus
flavescens L.)
Native annual.
Click thumbnail to enlarge
![Cyperus flavescens Cyperus flavescens](images/cyperus_flavescens.gif)
NWI status:
OBL
Seeds (achenes)
three-angled; flowers with three stigmas
Spikelets
in dense heads
Bearded
flatsedge (Cyperus
squarrosus L.)
Native annual.
![Cyperus squarrosus Cyperus squarrosus](images/cyperus_squarrosus.gif)
Note: The tips of the scales are strongly
recurved. This is
a small plant that grows in drawdown areas along lake shorelines.
NWI status:
OBL
Marsh
flatsedge (Cyperus
pseudovegetus Steud.)
Native perennial.
![Cyperus pseudovegetus Cyperus pseudovegetus](images/cyperus_pseudovegetus.gif)
Note: Similar in appearance to breaded flatsedge,
but much
taller ans lacking recurved scales.
NWI status:
FACW
Spikelets
not in dense heads; inflorescence long and string-like
Tapertip
flatsedge (Cyperus
acuminatus Torr. &
Hook. ex Torr.)
Native perennial.
![Cyperus acuminatus Cyperus acuminatus](images/cyperus_acuminatus.gif)
NWI status:
OBL
Poorland
flatsedge (Cyperus
compressus L.)
Native annual.
![Cyperus compressus Cyperus compressus](images/cyperus_compressus.gif)
NWI
status: FACW
Variable
flatsedge (Cyperus
difformis L.)
Introduced annual.
![Cyperus difformis Cyperus difformis](images/cyperus_difformis.gif)
Note: A serious pest of rice and corn fields in
Asia.
NWI
status: OBL
Redroot
flatsedge (Cyperus
erythrorhizos Muhl.)
Native
perennial.
![Cyperus erythrorhizos Cyperus erythrorhizos](images/cyperus_erythrorhizos.gif)
Note: A very large and robust plant.
One of the most common flatsedges in
Oklahoma.
NWI
status: OBL
Ricefield
flatsedge (Cyperus
iria L.)
Introduced annual.
![Cyperus iria Cyperus iria](images/cyperus_iria.gif)
Note: This species is considered one of the
World’s worst
weeds. It can profoundly affect rice
cultivation. Probably introduce to the
United States in the early 19th century from Asia.
NWI
status: FACW
Fragrant
flatsedge (Cyperus
odoratus L.)
Native annual.
![Cyperus odoratus Cyperus odoratus](images/cyperus_odoratus.gif)
NWI
status: FACW
Manyspike flatsedge (Cyperus
polystachyos Rottb.)
Native
perennial.
![Cyperus polystachyos Cyperus polystachyos](images/cyperus_polystachyos.gif)
NWI
status: FACW
Strawcolored flatsedge (Cyperus
strigosus L. )
Native Perennial.
![Cyperus strigosus Cyperus strigosus](images/cyperus_strigosus.gif)
Note: A very large and robust plant.
One of the most common flatsedges in
Oklahoma.
NWI
status: FACW
Last update: 2/23/04
Comments to : Bruce Hoagland
bhoagland@ou.edu
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