Cyperus involucratus Rottb. [syn.: C. alternifolius L. var. flabelliformis (Rottb.) Kük.] (Afr.) – A very rare and ephemeral garden throw-out or garden escape. Found on a dump in Couillet in the 1950’s. In 2018 observed self-sown in a private garden in Mechelen.
Cyperus involucratus is still regularly cultivated (especially indoors) and likely to be found on dumps elsewhere in Belgium. It is more or less widely naturalised in parts of southern Europe and probably spreading. An additional species, Cyperus albostriatus Schrad. (also native in Africa), is nowadays even more frequently cultivated, primarily in greenhouses. It is characterised by distinctive bracts and leaves with two whitish lateral nerves that are very prominent, especially when dried. It is likely to occur as a casual throw-out on dumps.
Selected literature
Baijnath H. (1975) A study of Cyperus alternifolius L., sens. lat. (Cyperaceae). Kew Bull. 30: 521-526.
Chen S.-H., Weng S.-H. & Wu M.-J. (2008) The umbrella sedge in Taiwan. Taiwania 53(3): 311-315.