Pontederia cordata: a new documented species
Pontederia cordata (Pontederiaceae) is a long lived perennial herbaceous aquatic species that roots within the mud substrate. The root system forms dense mats that cover the sediment. The species is native to the Americas. P. cordata grows in well saturated soils, at the interface between the aquatic and terrestrial environments, and in slow moving water bodies up to a depth of 40 cm. The species has been shown to form large monocultures in nutrient rich water bodies. P. cordata is a popular ornamental plant grown in gardens and parks. The species is widely traded in the horticultural industry. The invasive nature of P. cordata has been recorded in both the native and some of the introduced range. In South Africa, the species is recorded to compete with indigenous riverbank plant species and crop species when it encroaches in irrigated fields. In South Africa, P. cordata has been highlighted as forming dense stands which can block drainage canals and obstruct access to the edges of water bodies. In South Africa P. cordata has been recorded as being invasive in irrigation channels where it blocks water movement and drainage systems and can encroach onto agriculture land. In the EPPO region, P. cordata currently has a restricted distribution (the species is found in the wild in Belgium, France, Italy, Ireland, the Netherlands, Spain, Switzerland and the United Kingdom) but the species is seen more frequently growing as a garden/pond escapee. Due to the uncertainty concerning ecological and economic impacts coupled with a lack of information on the invasiveness of the species within the EPPO region - at present - this species does not warrant inclusion on the EPPO Alert List – instead a mini-datasheet has been prepared and will be published on the EPPO website.
EPPO website. http://www.eppo.int/INVASIVE_PLANTS/iap_list/data_sheets/15-20677_DS_Pontederia_cordata.doc
National Botanic garden of Belgium (2015) Pontederia cordata manual of the alien plants of Belgium. http://alienplantsbelgium.be/content/about-us.
Q-bank (2013) Comprehensive databases of quarantine plant pests and diseases. http://www.q-bank.eu/