T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Lythrum salicaria (Purple loosestrife)

Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Myrtales
Family: Lythraceae
Genus: Lythrum
Species: L. salicaria
Binomial name: Lythrum salicaria
Synonym: Lythrum virgatum
Common names: Purple loosestrife, Spiked loosestrife, Purple lythrum, European wand loosestrife.

Lythrum salicaria is an invasive species of an erect, hairy, herbaceous perennial plant that is native to Europe, Asia, northwest Africa, and south-eastern Australia. Lythrum salicaria was introduced into temperate New Zealand and is now found in Levin, Whanganui, Canterbury, Otago and Southland. It can rapidly invade the margins of lakes and slow-flowing rivers, fens and marshes where it can form impenetrable stands that can exclude all other plant species. It causes a decline in biological diversity as native food and cover plant species are completely crowded out, and the life cycles of organisms from waterfowl to amphibians to algae are affected.

Lythrum salicaria can grow 1–2+ m tall, forming clonal colonies with numerous erect stems growing from a single, dense, woody root mass. A plant can produce up to 50 stems per rootstock. The stems are reddish-purple or red to purple and square in cross-section. The leaves are lanceolate, 3–10 cm long and 5–15 mm broad, downy and sessile, and arranged opposite or in whorls of three. They die off in winter.
From December to February plants develop densely, hairy, flowerhead spike (20-25 cm long). The flowers are a reddish purple, 10–20 mm diameter, with six petals (occasionally five) and 12 stamens, and are clustered tightly in the axils of bracts or leaves; there are three different flower types, with the stamens and style of different lengths, short, medium or long; each flower type can only be pollinated by one of the other types, not the same type, thus ensuring cross-pollination between different plants. 
The fruit is a small 3–4 mm blackish capsule containing numerous minute seeds. A single plant may produce up to 2.7 million tiny seeds annually. Seeds are carried by wind and water. Seeds germinate in moist soils after overwintering. The plant can also sprout anew from pieces of root left in the soil or water. Once established, loosestrife stands are difficult and costly to remove.


The plant's leaves often turn bright red through dehydration in early autumn. The dead stalks from previous growing seasons are brown.

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/