A perennial herb to shrub with erect stems, reaching about 1.5 metres tall, forming rounded multi-stemmed clumps to about 1 metre wide.
It has a large natural distribution in New South Wales, growing on the south coast, tablelands and western slopes from the Victorian border, (as far west as Deniliquin), northwards in a common, slightly-patchy distribution to the Queensland border, mostly on the tablelands in the north – as far west as areas such as Macquarie Marshes. It extends into Queensland to about Gympie with a few records well west of Bundaberg. It is common through much of Victoria with the expection of the north-western areas. It extends in South Australia, around Mt Gambier and the greater Adelaide-area. It is found in the general eastern half of Tasmania. It is also native to New Zealand as well as the northern hemisphere in the USA, Europe and parts of Asia.
It is typically found on moist-swampy and marshy ground – in swampland and broad creek and river-flats. It forms part of swampy herblands and shrublands.
Lythrum spp. have simple leaves, arranged oppositely, alternately to whorled across species. In this species, they are light to mid green, narrow-ovate, to 70 mm long and to 15 mm wide, with the bases clasping the stem.
Lythrum spp. produce flowers either solitarily or in small cymes, in leaf axils. Flowers are typically 6-merous with 6 sepals and petals (the latter usually present) with 6 to 12 stamens and 1 carpel (bisexual). In this species, clusters of flowers are produced in the axils of reduced leaves, with flowers having 5 ot 6 petals and sepals; each flower up to 2 cm across and deep purple; overall flowers are produced in long leafy spikes.
The fruit of Lythrum is a capsule with 2 valves, around 1 cm long in this species.
Author’s notes: This is an ideal plant to grow in aquatic environments. Our plants usually die down in winter but bounce back in spring. It may not thrive in dry areas but does well in any frequently boggy spot. Plants reportedly die back in winter to root stocks and will re-emerge in spring.
Best planted in a poorly-drained area on a heavier soil, in part-shade to full sun. It can be planted next to ponds or even in ponds, as well as moist creeklines or rehabilitated wetlands.
Prune plants after flowering to encourage flushes of new growth.
Propagate from cuttings that produce roots rapidly.
This species may be able to regenerate from seed after any fire event.
Lythrum is a genus of about 36 species with a large world-distribution. Australia has 5 species (2 endemic) – occurring in all states and territories. NSW currently has 4 species.
Lythrum – reportedly from the Greek lythron (λύθρον) – which means “blood” or “gore” – which refers to the flower-colour (perhaps more so when they are dried).
salicaria – latin – referring to a connection to the Salix genus (Willow) – referring to the general foliage appearance.
This species is not considered to be at risk of extinction in the wild.
Oxford University Plants – Lythrum salicaria profile page https://herbaria.plants.ox.ac.uk/bol/plants400/Profiles/kl/Lythrum
Australian National Herbarium – Lythrum salicaria profile page https://www.anbg.gov.au/gnp/gnp2/lythrum-salicaria.html
Wrigley, J.W. & Fagg, M.I. (2001). Australian Native Plants – Propagation, cultivation and use in landscaping. 4th edition. New Holland Publishers, Pty. Ltd. Australia.