Pontederia cordata

The species grows as an emergent plant, that is, in flooded conditions, so the plant is generally dependent upon aerenchyma in the stem to carry oxygen into the roots. Its metabolism is, however, also tolerant of low soil oxygen. It is often found in areas where water levels fluctuate naturally, with spring flooding and later summer emergence. Apart from flooding, the species is also influenced by soil fertility, tending to grow in the more fertile bays of large lakes, for example. Like many aquatic plants, it is negatively affected by salinity and grazing. It is also negatively affected by competition from other wetland plants. Like many wetland plants, it can survive unfavorable conditions as buried seeds in the soil. In a 36-year study on this species in a sinkhole pond, it was found to have an inverse relationship with American Lotus (Nelumbo lutea), declining in years with high American lotus abundance and increasing in years in with low American lotus abundance. ==Flowers==

The plant flowers in late summer. The purple flowers have yellow markings which may assist in attracting bees for pollination. Two species known to pollinate the flowers are Melissodes apicatus and Dufourea novaeangliae. Once the plant begins to produce seeds, the stem supporting the inflorescence bends to submerge the fruits and seeds. Like many wetland and aquatic plants, the species can reproduce asexually by means of branching rhizomes, and hence can form large clonal stands. , Ontario The small seed pods are green and warty, and are released into the water when ripe. ==Cultivation==

This plant is cultivated as an ornamental garden pond plant, and has gained the Royal Horticultural Society's Award of Garden Merit. ==Uses==

The young leafstalks can be eaten raw (with the unripe fruits stripped off) or cooked. The seeds are edible raw, and can be ground into grain. ==References==