Cyperus of Arkansas

 

Revised October 1, 2012

 

Cyperus of Arkansas: an annotated list

 

This page provides a list of all Arkansas Cyperus sedges, as of March 2008. I am adding brief hints for the field identification of each taxon, eventually. Taxonomic problems have yet to be settled on the genus in Arkansas.

Taxonomy of species marked with an asterisk (*) matches the "Checklist of the Vascular Plants of Arkansas", Gentry, et al., 2007. I've added numbers with AFC to determine a count of Arkansas taxa.

Specimen data from Sedgehead's personal records of specimens in various herbaria he's reviewed or collected. Some info below comes from Smith's keys or 1988 atlas or from Flora of North America. Most comes from my personal experience.

Cyperus acuminatus Torr. & Hook. * AFC01

This species appears to be more frequent in northern Arkansas than in the south. I've found it often along roadsides. Its absence in Smith's (1994) keys appears to be an oversight. The taxon is fairly easy to recognize in the field, but can be confused with some other taxa. My records show it in Grant, Phillips, and Pulaski counties as well as 14 counties in the northern half of the state.

Cyperus alternifolius.

 

Papyrus, this species, apparently rarely escapes cultivation in Arkansas and is not recognized as escaped by the Arkansas Flora Committee.

Cyperus bipartitus Torr. * AFC02

This small scaled species occurs at widespread locations and like many in the genus is probably more common than collections currently indicate. I've seen records from Hot Springs, Union, and Washington counties, and where I've worked in north central Arkansas we have records in Baxter, Fulton, and Izards counties.

Cyperus compressus L. * AFC03

This taxon has always confused me. UARK reports specimens from Pulaski, Garland, and Chicot counties. I've not reviewed them. Smith reported it from four counties including Garland.

Cyperus croceus Vahl * AFC04

Synonym: Cyperus globularis

I know this species poorly, despite the fact I've got records from 17 counties. It appears to be absent in the northern two tiers of counties, except present in Marion. And no records exist north and east of Cleburne and Arkansas counties.

Cyperus cuspidatus Kunth in A. von Humboldt, et al. * AFC 05

This taxon is not covered in Smith's (1994) keys or atlas (1988) for Arkansas flora. But Smith apparently recorded it in Drew County as his collection number 10,436.

Cyperus difformis L. * AFC 06

I welcome this naturalized taxon from the old world (Flora of North America, vol. 23). While botanists and some few naturalists fight against invaders, I side with the majority of Americans, welcoming species from other counties we bring in intentionally or accept as a fact of life. For the average American, who cares if weeds invade? We don't.

Cyperus echinatus (L.) Wood * AFC 07

Synonym: Cyperus ovularis (Michx.) Torr.

One common Arkansas taxon this is easy to recognize. The spherical heads cannot be mistaken for other Arkansas Cyperus. I've got records for 2/3 of Arkansas' counties, but need Madison, Boone, Sharp, and Randolph in north Arkansas.

Cyperus erythrorhizos Muhl. * AFC 08

This common, weedy species is fairly easy to recognize.

Cyperus esculentus L. var. esculentus

Synonym: Cyperus esculentus L.

I'm not sure why the Arkansas Flora Committee does not recognize this taxon as occuring in Arkansas. I have seen records from at least Crittenden County identified as this variety by Richard Carter at VSC. We need to work on this one.

Cyperus esculentus L. var. leptostachyus Boeck. * AFC 09

Synonym: Cyperus esculentus L.

Ok, I'm getting bored and need to come back to this taxon later. Its confusable with the preceeding taxon.

Cyperus flacescens L.

Synonym: Cyperus flacescens L. var. poiformis (Pursh) Fern.

Flora of North America says the variety is "not supported" based on documented research.

Cyperus flavicomus Michx.

I need to write up info on this species.

Cyperus grayioides Mohlenbrock

John Logan found this species of deep sandy soils in southwest Arkansas at a few locations in the late 1990s, new to Arkansas.

Cyperus haspan L.

Cyperus haspan is an interested beast. I found it only streamsides, so this plant "likes its feet wet" as Tony Reznicek said of Carex ozarkana.

Cyperus hystricinus Fern.

I need to write up info on this species.

Cyperus iria L.

I need to write up info on this species.

Cyperus lancastriensis Porter

I need to write up info on this species.

Cyperus lupulinus (Spreng.) Marcks

Synonym: Cyperus aristatus Rottb.

Cyperus lupulinus may have two valid variety's I've not checked out, ssp. lupulinus and ssp. macilentus

Cyperus odoratus L.

I need to write up info on this species.

Cyperus oxylepis Nees ex Steud.

I need to write up info on this species.

Cyperus plukenetii Fern.

This sedge, Cyperus plukenetii is a robust plant of deep sandy soils, at least in Louisiana. It can be told from many Cyperus species by its hairy stems!

Cyperus polystachyos Rottb. var. texensis

Synonym: Cyperus aristatus Rottb.

I need to write up info on this species.

Cyperus pseudovegetus Steud. var. pseudovegetus

Synonym: Cyperus aristatus Rottb.

This neat plant is common in roadside ditches, and is one of the easier species in the genus to learn.

Cyperus re* species note! Several species in this genus have VERY similar names, which seem to have NO relation to any actual relationship between them. Some are wetland species, some are of roadsides, and some are of natural habitats primarily. One just has to sort them out. I would advise a careful reading of any keys to make sure you have the correct "re*" species. It is easy to pick the wrong one if you are in a hurry, which totally messes up your identification.

Cyperus refractus Torr.

I need to write up info on this species.

Cyperus retroflexus Buckley

I need to write up info on this species.

Cyperus retrofractus (L.) Torr.

I need to write up info on this species.

Cyperus retrorsus Chapm.

This "re*" species is easier to identify than most Cyperus. It has compact heads similar to C. echinatus, but they are smaller and oblong. Look for it on roadsides, where it is actually common (at least in southern Arkansas, I've not checked north Arkansas yet). It often grows as very widely scattered plants, so once you find one, like many Cyperus you may have to hunt a few minutes to find more. I have found colonies with 30 or more plants scattered over several square yards, but more often find individuals scattered up to 100 yards apart. Don't worry about hurting the population though. This weedy species will often be found at every stop in a county on roadsides, but with only a few plants found in each 15 minute collecting stop.

Cyperus rotudus L.

I need to write up info on this species.

Cyperus schweinitzii Torr.

I need to write up info on this species.

Cyperus squarrosus L.

Synonym: Cyperus aristatus Rottb.

Cyperus squarrosus L. has been documented from Chicot and Montgomery counties as well as 16 counties from Perry and Mississippi counties, north in Arkansas. What to find this taxon? Look for dense stands of tiny plants growing in drawn down lakes or in roadside ditches where water levels have dropped as the season dries. Few other Cyperus sedges grow maturely at this short stature of less than six inches.

Cyperus strigosus L.

Perhaps Arkansas' most widespread Cyperus, this plant is often abundant in roadside ditches. Yet, it is also found as scattered individuals at some sites.

Cyperus surinamensis Rottb.

I need to write up info on this species.