Click on images to enlarge
flowering plants (Photo: Sheldon Navie)
flower head (Photo: Sheldon Navie)
close-up of flowers (Photo: Sheldon Navie)
fruit (Photo: Sheldon Navie)
Pontederia as ornamental plant in pond (Photo: Agnes Lusweti)
seeds (Photo: Sheldon Navie)
leaf (Photo: Sheldon Navie)
back of leaf (Photo: Sheldon Navie)
leaf petiole (Photo: Sheldon Navie)
Eastern North America, Central and South America.
Locations within which Pontederia cordata is naturalised include parts of Australia, Europe, Africa and western North America.
Pontederia cordata is invasive in Kenya and is present in Tanzania and Uganda (A.B.R. Witt pers. obs.). It has been recorded in inland fresh water lakes and reservoirs, including artificial dams, reservoirs and in ponds around towns.
Emergent water plant of water and riverine habitats.
Pontederia cordata is a long-lived (perennial), rooted freshwater plant 1-2 m tall that grows in clusters and forms colonies.
The stems are smooth, emerging above the water surface and branched, each bearing a leaf and a flower spike. The leaves are light or yellowish green, cordate in shape, 230 mm long by 70 mm wide. Leaves appear one per stem each with a long petiole that clasps the stem.
The flowers of P. cordata are blue in colour and appear at the terminal end of the stem. The flowers are on long spikes 50-150 mm long. Each flower is 15 mm long and the upper petal has a yellow blotch in the centre. This plant is sterile and does not produce fruits and seed.
This plant spreads vegetatively from fragmented rhizomes.
Pontederia cordata has sometimes been confused with Eichhornia crassipes (water hyacinth another introduced water weed of the same family. These species can be readily distinguished by the following differences:
Pontederia cordata is an ornamental plant. However, this use cannot compensate for this plant's overall negative impacts.
Pontederia cordata is a competitive weed of the inland waters and artificial ponds and water masses. It has been listed as a Category 3 invader in South Africa (no further planting is allowed - except with special permission - nor is trade in propagative material. Existing plants must be prevented from spreading).
The precise management measures adopted for any plant invasion will depend upon factors such as the terrain, the cost and availability of labour, the severity of the infestation and the presence of other invasive species.
The best form of invasive species management is prevention. If prevention is no longer possible, it is best to treat the weed infestations when they are small to prevent them from establishing (early detection and rapid response). Control is generally best applied to the least infested areas before dense infestations are tackled. Consistent follow-up work is required for sustainable management.
The editors did not find any specific information on the management of this species.
Not listed as a noxious weed by the state or governments in Kenya, Tanzania and Uganda.
Henderson, L. (2001). Alien weeds and invasive plants. A complete guide to declared weeds and invaders in South Africa. Plant Protection Research Institute Handbook No. 12, 300pp. PPR, ARC South Africa.
Henderson, L. and Cilliers, C.J. 2002. Invasive aquatic plants-a guide to the identification of the most important and potentially dangerous invasive aquatic and wetland plants in South Africa. PPRI Handbook No. 16, Agricultural Research Council, Pretoria.www.arc.agric.za/uploads/images/0_SAPIA_NEWS_No._17.pdf.
Agnes Lusweti, National Museums of Kenya; Emily Wabuyele, National Museums of Kenya, Paul Ssegawa, Makerere University; John Mauremootoo, BioNET-INTERNATIONAL Secretariat - UK.
This fact sheet is adapted from The Environmental Weeds of Australia by Sheldon Navie and Steve Adkins, Centre for Biological Information Technology, University of Queensland. We recognise the support from the National Museums of Kenya, Tropical Pesticides Research Institute (TPRI) - Tanzania and Makerere University, Uganda. This activity was undertaken as part of the BioNET-EAFRINET UVIMA Project (Taxonomy for Development in East Africa).
BioNET-EAFRINET Regional Coordinator: firstname.lastname@example.org