''Cyperus trachysanthos'' is a rare species of

sedge The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus ''Carex'' wit ...

known by the common names ''pu`uka`a'' and sticky flatsedge. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

, where it is known from

Kauai Kauai, () anglicized as Kauai ( ), is geologically the second-oldest of the main Hawaiian Islands (after Niʻihau). With an area of 562.3 square miles (1,456.4 km2), it is the fourth-largest of these islands and the 21st largest island ...

and

Oahu Oahu () (Hawaiian language, Hawaiian: ''Oʻahu'' ()), also known as "The Gathering place#Island of Oʻahu as The Gathering Place, Gathering Place", is the third-largest of the Hawaiian Islands. It is home to roughly one million people—over t ...

. It was known from Niihau,

Molokai Molokai , or Molokai (), is the fifth most populated of the eight major islands that make up the Hawaiian Islands, Hawaiian Islands archipelago in the middle of the Pacific Ocean. It is 38 by 10 miles (61 by 16 km) at its greatest length an ...

and

Lanai Lanai ( haw, Lānai, , , also ,) is the sixth-largest of the Hawaiian Islands and the smallest publicly accessible inhabited island in the chain. It is colloquially known as the Pineapple Island because of its past as an island-wide pineapple pl ...

, but it has been extirpated from these islands.''Cyperus trachysanthos''.
The Nature Conservancy.USFWS
''Cyperus trachysanthos'' Five-year Review.
August 2010. It is a federally listed

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

of the United States. This plant is a rhizomatous perennial flowering plant which produces clumps of stems up to about 45 centimeters in maximum height. There are plentiful hairlike green leaves which may be longer than the stems. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

is made up of a few heads of up to 30 spikelets each. The spikelet is about a centimeter long and has up to 20 yellow-brown flowers covered by yellow-brown to reddish

glumes In botany, a glume is a bract (leaf-like structure) below a spikelet in the inflorescence (flower cluster) of grasses (Poaceae) or the flowers of sedges (Cyperaceae). There are two other types of bracts in the spikelets of grasses: the lemma and ...

. The plant grows in

wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...

habitat such as

seeps A petroleum seep is a place where natural liquid or gaseous hydrocarbons escape to the earth's atmosphere and surface, normally under low pressure or flow. Seeps generally occur above either terrestrial or offshore petroleum accumulation stru ...

mudflat Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal fl ...

s, and

marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found at ...

es. Hau (''Hibiscus tiliaceus'') is often found alongside the sedge. Generally, the habitat is seasonally dry. This species has been reduced to seven populations, one on Kauai and six on Oahu. The Kauai population contains about 300 individuals. On Oahu, the plant occurs at several locations, including Diamond Head, where 40 individuals have been counted, and

Lualualei Lualualei, Hawaii is the largest coastal valley on the leeward side of Oahu in Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. ...

, where there are over 300. There is a total of perhaps 1000 plants, but the population numbers vary by

rainfall Rain is water droplets that have condensed from atmospheric water vapor and then fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides water f ...

abundance. Threats to this endangered species include the

destruction Destruction may refer to: Concepts * Destruktion, a term from the philosophy of Martin Heidegger * Destructive narcissism, a pathological form of narcissism * Self-destructive behaviour, a widely used phrase that ''conceptualises'' certain kind ...

of its wetland habitat, and natural disasters that could conceivably destroy entire populations, such as

hurricane A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...

Exotic plant species Exotic may refer to: Mathematics and physics * Exotic R4, a differentiable 4-manifold, homeomorphic but not diffeomorphic to the Euclidean space R4 *Exotic sphere, a differentiable ''n''-manifold, homeomorphic but not diffeomorphic to the ordinar ...

such as billygoat weed (''Ageratum conyzoides''),

scarlet pimpernel ''The Scarlet Pimpernel'' is the first novel in a series of historical fiction by Baroness Orczy, published in 1905. It was written after her stage play of the same title (co-authored with Montague Barstow) enjoyed a long run in London, having ...

(''Anagallis arvensis''),

feather fingergrass ''Chloris virgata'' is a species of grass known by the common names feather fingergrass feathery Rhodes-grass and feather windmillgrass. Distribution It is native to many of the warmer temperate, subtropical, and tropical regions of the world, i ...

(''Chloris virgata''), and lantana (''Lantana camara''), are a threat. Feral goats, off-road vehicles,

fire Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction Product (chemistry), products. At a certain point in the combustion reaction, called the ignition ...

and

pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...

are threats to ''Cyperus trachysanthos'' on Oahu.

References

External links

USDA Plants Profile
{{Taxonbar, from=Q5200211 trachysanthos Endemic flora of Hawaii Biota of Kauai Biota of Oahu Plants described in 1872