Ontario
Weeds: Purple loosestrife
Table of Contents
- Name
- Other Names
- Family
- General Description
- Stems and Roots
- Flowers and Fruit
- Habitat
- Similar Species
- Related Links
Name: Purple loosestrife, Lythrum salicaria
L.,
Other Names: salicaire, Spiked loosestrife,
salicaire commune, lythrum salicairel
Family: Loosestrife Family (Lythraceae)
General Description: Perennial, reproducing
only by seed.
Photos and Pictures

Purple loosestrife (A - flowering spikes; B - a typical strand).

Purple loosestrife.
Stems & Roots: Stems tall, erect,
60-120cm (24-48in.) high, somewhat branched, usually finely hairy,
more or less square in cross-section, especially where the leaves
are opposite; leaves opposite (2 per node) or sometimes whorled (3
or more per node), stalkless, broad near the base and tapering towards
the tip, 3-10cm (1¼-4in.) long, finely hairy; upper leaves
and those in the inflorescence usually alternate (1 per node) and
smaller than the lower ones.
Flowers & Fruit: Flowers in dense
terminal spikes; sepals united into a column with 8 to 10 or 12 prominent
green veins and ending in several, long, thin, pointed lobes; petals
5 to 7, red-purple, 7-10mm (¼-2/5in.) long, very showy; stamens
several and 1 pistil; seedpod small, containing many tiny seeds. Flowers
from June to autumn.
Habitat: Purple loosestrife was introduced
from Europe but is now widely naturalized in wet meadows, river flood-plains,
and damp roadsides throughout most of Ontario.
Similar Species: Its opposite leaves and
square stems resemble plants of the Mint Family but it is distinguished
by having separate petals, a seedpod with many fine seeds, and it
lacks the minty odour.
Related Links
... on general Weed
topics
... on weed identification, order OMAFRA Publication 505: Ontario Weeds
... on weed control, order OMAFRA Publication 75: Guide To Weed Control
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