Lythrum salicaria (Purple Loosestrife)
Botanical Information
| Family | Lythraceae |
| Genus | Lythrum |
| Species | salicaria |
| Category | Perennials, Wildflowers & Weeds |
| Origin | Europe and temperate Asia but considered an invasive species in North America. |
| Ethnobotanical Uses Disclaimer | Listed as an exotic invasive species the World Conservation Union’s list of 100 Worst Invasive Species. In some areas it is illegal to plant. |
Details
| USDA Hardiness Zone | 4 - 9 |
| USDA Hardiness Ref. | |
| Canadian Hardiness Zone | 3 |
| Canada Hardiness Ref. | |
| RHS Hardiness Zone | H3 - H7 |
| RHS Hardiness Ref. | |
| Temperature (°C) | -34.4 - (-3.9) |
| Temperature (°F) | -30 - 30 |
| Height | 0.6 - 1.2 m |
| Spread | 0.6 - 1.2 m |
| Growth | Fast |
| Flowering Period | May, June, July, August, September |
Description and Growing Information
| General Description | An invasive wetland perennial. |
| ID Characteristic | Brightly coloured flowers. |
| Shape | Clumps. |
| Propagation | Self seeding and through division of rhizomes. |
| Cultivation | Best grown in medium to wet soils in full sun to light shade. Flowering spikes should be deadheaded immediately after bloom to prevent self-seeding. Plants may be sheared to the ground after flowering or if foliage becomes tattered from insect damage. If sheared in mid-summer, new foliage generally will appear in 2 weeks with a possible autumn rebloom. Plants are most invasive in wet soils. |
| Notable Specimens | Port Franks, Ontario, Canada. |
| Habitat | Wetlands, including lake, pond, stream and swamp margins. |
| Leaf Description | Downy, stemless, stiletto-shaped leaves grow up to 10 cm and are opposite or sometimes in whorls of three. |
| Flower Description | Flowers appear in dense terminal spikes up to 45 cm long. |
| Colour Description | Foliage is green. Flowers are bright magenta to purple. |
Photographs
Lythrum salicaria, form.
Lythrum salicaria, leaf.
Lythrum salicaria, flower.
Scanning electron microscope image of pollen grain.