Ontario Weeds: Purple loosestrife
Excerpt from Publication 505, Ontario Weeds,
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Table of Contents
- Other Names
- General Description
- Stems and Roots
- Flowers and Fruit
- Similar Species
- Related Links
Name: Purple loosestrife, Lythrum
Other Names: salicaire, Spiked loosestrife, salicaire commune, lythrum salicairel
Family: Loosestrife Family (Lythraceae)
General Description: Perennial, reproducing only by seed.
Purple loosestrife (A - flowering spikes; B - a typical strand).
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.
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