Cyperpus congestus Vahl
Mariscus congestus Vahl
This is a perennial (living longer than 1 season) sedge with a short thick rhizome (under ground stem connecting plants) and are generally 40-100cm tall. Culms (stems) are smooth, slightly swollen at the base , also pink/red at the base and are triangular in cross section.
Leaves are shorter than culms (stems). Leaves are 4-8 mm broad, and are ridged with deep dip down the centre. As for all Cyperaceae the leaf sheaths are closed around the stem and there are no ligule(appendage) inside the base of the leaf.
Each stem may have 2-7 inflorescence (flower heads). Each inflorescence may have up to 20 or so spikelets or branches. Each spikelet is 10-28mm long, quite smooth and delicate and red/brown in colour. The name congestus means crowded and probably refers to how snug the fruit lies along the spikelet. The bracts (leaves surrounding the inflorescence) are quite a bit longer than the spikelets.
Fruit is a tiny nut which is triangular in cross section, narrow to pear-shaped and dark brown to black.
This plant is quite easily removed using a knife or trowel, care should be taken with the seed heads as seed can be released on contact.
Other plants easily confused with this plant
The inflorescence (flowerhead) of this species is quite unique in colour and shape to other Cyperus, the red base is also a useful characteristic.
Sources & References
"Weeds - an illustrated botanical guide to weeds of Australia" by B. A. Auld and R. W. Medd
"Field Guide to Native Plants of Sydney" by Les Robinson
"Plantnet FloraOnline" (2005) http://plantnet.rbgsyd.nsw.gov.au/
Prepared by Justin KY Chu, July 2005
Checked by IEWF, March 2006