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Integrated Crop Management
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Purple loosestrife

Purple loosestrife - Lythrum salicaria L.

Family: Lythraceae (Loosestrife family)
Life cycle: Perennial, reproduces by seed.
Habitat: Wetlands
Native status: Introduced

General description: An erect plant reaching heights of 5 to 6 ft with many branches developing from the crown. Leaves are sessile, linear to lanceolate up to 4 in long, downy with smooth edges; leaves are opposite or in whorls of three. Stems are square or six-sided. Purple flowers are produced in late summer in terminal spikes up to 1.5 ft long.

Key ID traits: Sessile, lanceolate leaves in opposite or whorled arrangement; Square stems, purple spikes.

Miscellaneous: Purple loosestrife was sold commercially for landscaping and as a nectar-bearing plant for honeybees. Many cultivated varieties were marketed as being sterile, but were found to produce viable seed. Sales and distribution are now illegal in Iowa, but purple loosestrife is not classified as noxious. Biological efforts using insects have been implemented in Iowa and other states.

leaves are opposite, sesile, and lanceolate shaped. Stems are distinctly ridged
Leaves are opposite, sessile, and lanceolate shaped. Stems are distinctly ridged.
plants produce numerous spikes of purple flowers
Plants produce numerous spikes of purple flowers
Authored by:
Bob Hartzler
Bob Hartzler
  • Retired Weed Scientist and Professor of Agronomy
Dr. Bob Hartzler is a former professor of agronomy and a former extension weed specialist with a Ph.D. in Crop Physiology from Iowa State University. He conducted research on weed biology and how it impacts the efficacy of weed management programs in corn and soybean. Dr. Hartzler also taught undergraduate classes in weed science and weed identification.
Meaghan Anderson
Meaghan Anderson
  • Field Agronomist in Central Iowa
Meaghan Anderson is a field agronomist serving nine counties in central Iowa and an extension specialist with Iowa State University Extension and Outreach. Areas of expertise include weed management, weed biology, cover crops, corn and soybean management, and integrated pest management.

Meaghan holds a bachelor's degree in agronomy and a master's degree in crop production and physiology (focus: weed science) from Iowa State University.
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