Sessile joyweed – Alternanthera sessilis

Weed Seed - Sessile joyweed (Alternanthera sessilis)

Sessile joyweed is an invasive plant that competes with crops for valuable nutrients and water. It reduces the yield and quality of crops such as corn, rice, soybeans and vegetables. It grows in both wet and dry environments. In aquatic systems, it can block irrigation pipes and canals.

Where it's found

Sessile joyweed has not been found in Canada. It is native to Asia and has been introduced into tropical and subtropical areas of Africa, Australia, the Caribbean, Central and South America and the south-eastern United States. Typical habitats include a variety of agricultural crops, gardens, disturbed areas and aquatic systems. Although tropical, it is capable of surviving certain areas of south-western British Columbia.

What it looks like

Sessile joyweed is either a creeping perennial or a short-lived annual, depending on the environment. It is extremely adaptable, and may grow either on dry land or partially submerged in water. It is usually flat and highly branched, with opposite, stalk-less leaves and small, silver-white to pinkish flowers that grow where the leaf meets the stem.

How it spreads

Sessile joyweed has been widely spread around the world as an aquarium or water garden plant, or as a food or medicinal plant. It may also be spread unintentionally as a contaminant of other crops. It reproduces mainly by seed—its seeds are spread naturally by wind and water.

What you can do about it

  • Avoid planting invasive plants in your garden.
  • Use clean, high quality seed that is certified if possible.
  • Declare all plants and related products when returning to Canada.
  • Contact your local Canadian Food Inspection Agency (CFIA) office if you suspect you have found this invasive plant. The CFIA will follow up and determine if further action is needed.

To find out more, visit www.inspection.gc.ca/invasive.

Sessile joyweed flower
Sessile joyweed flower
J.M. Garg
Sessile joyweed leaves
Sessile joyweed leaves
Forest and Kim Starr
Sessile joyweed plants
Sessile joyweed plants
J.M. Garg
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