Cyperus gilesii, commonly known as Giles' flat-sedge,[1] is a sedge of the Cyperaceae that is native to Australia.
The annual or perennial sedge has a slender tufted habit. It has smooth trigonous or triquetrous shaped culms that are typically in height with a diameter of diameter.[2]
The septate to nodulose leaves are shorter than the culms and have a width of about . The sedge flowers in spring and summer producing simple inflorescences with one to five branches that have a length of around . The dense flower clusters are subdigitate with a hemispherical to globose shape and a diameter of around . There are one to three leaf-like involucral bracts. There are many flattened spikelets per cluster that have a length of and a width of containing 8 to 34 golden brown to red-brown flowers. After flowering a trigonous very narrow-ellipsoidally shaped red-brown to grey-brown nut forms that has a length of and a diameter.[2] [1]
The species was first formally described by the botanist George Bentham in 1878 in the work Flora Australiensis.[3] The specific epithet honours the explorer William Ernest Powell Giles who led five major expeditions throughout central Australia.[1]
C. gilesii is found throughout Australia. It is common throughout Queensland, northern South Australia, northern New South Wales and eastern parts of the Northern Territory.[4] [1] In Western Australia it only occurs only rarely in the Pilbara region. It is often situated ephemerally wet situations, including inland stream and river banks, floodplains and roadside drains.[2]