Persicaria attenuata  (R.Br.) Soják  1974

pronounced: per-sih-KAR-ee-uh at-ten-yew-AH-tuh

 (Polygonaceae —  the dock family)

synonym: Polygonum attenuatum  R.Br. 1810

pronounced: poh-lee-GO-num at-ten-yew-AH-tum

common names:  Smartweed, Watersmart Weed, Hairy Knotweed

Persicaria persicaria attenuatasmartweedpersicaria attenuataleavesis a Late Latin word for the peach tree, given to this genus because of the supposed similarity of its leaves to that of the peach. The classical Latin word for a peach was malum Persicum, Persian apple. Attenuata is from the Latin attenuatus, weak, meagre, reduced.

Smartweed is widespread in the tropics and subtropics of Africa, Asia and Australia. It grows in and beside water, and often forms large patches with long floating stems that root at the lowest nodes. In Australia it is found in the northern parts of Western Australia and the Northern Territory, and in most of Queensland and NSW. It is also found in a few parts of northern Victoria. The plants photographed grow on the margins of the lagoon in the Horseshoe Bay wetlands. This plant is one of those collected in 1770 by Banks and Solander during the voyage of the Endeavour. It was collected at the Endeavour River (Cooktown).

persicaria attenuatafloweringpersicaria attenuataflowersThis is a robust hairy rhizomatous herb that grows up to 2 m in height, with branched stems. These stems creep from the base and root at the nodes, becoming hollow as they age. The leaves are simple and alternate, the ochrea cylindrical and up to about 4 cm long, the surface coarsely villous, and the apex having a fringe of bristles. The petiole is quite short, up to about 7 mm long; the blade is  narrowly ovate, more-or-less falcate, with the base tapering evenly to the stem, while the tip is long and pointed; they are anything up to 25 cm long and 5 cm wide, pubescent, with prominent veins below.

The inflorescence is a panicle of 2 to 5 spike-like racemes. The tiny flowers are bisexual, with a campanulate perianth, white or pink lobes, 5-8 stamens, and a superior ovary. The plant flowers for much of the year.

persicaria attenuataflower detailThe fruit is a lens-shaped nut, about 3 mm long, and brownish black in colour, shiny, and with short spiny tips.

Persiciana attenuata is very variable, and 3 subspecies have been distinguished, based in the hairiness of the ochrea and the leaf, and the leaf and fruit form. Ssp. africana is confined to Africa, ssp. pulchra  to eastern Asia, and ssp. attenuata to south-east Asia and Australia.The leaves of the plant are used as a salad plant or as a cooked vegetable in parts of Africa, particularly in Benin and Tanzania, and are also grazed by stock. In south-east Asia it is eaten with food as a tonic and to purify the blood. In East Africa it is much used medicinally, especially to treat syphilis and rheumatism. The plant is not cultivated, but is collected from the wild.

Information about medicinal qualities of plants, or about their use as medicines, is for interest only, and is not intended to be used as a guide for the treatment of medical conditions.

Photographs taken in Horseshoe Bay, 2013

Page last updated 14th January 2017

 

 

 

 

 

 

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