Family: Pontederiaceae
Species: Pontederia cordata L.
Common name: Pontederia - English: Pickerel weed
Etymology
Linnaeus named the genus Pontederia in honour of the illustrious Italian botanist Giulio Pontedera, who was the prefect of the Botanical Garden of Padua.
Description
Pontederia cordata is an aquatic marsh plant that forms a rosette of large, bright green, almost jade-coloured leaves, which are heart-shaped, thick, and very spongy. In summer, it produces a very showy, spike-shaped inflorescence emerging from the extension of a leaf petiole; this inflorescence bears numerous blue-lilac flowers with a yellow spot that helps attract bees for pollination. The flowering period is extended, continuing until the arrival of autumn.
When the plant begins to produce seeds, the stem that supports the inflorescence bends to submerge the fruits and seeds. The seeds require a period of stratification to germinate and can be dispersed by water, wind, and animals; in such cases, new seedlings may take more than 5 years to reach full vegetative development.
Like many aquatic and humid-zone plants, P. cordata can reproduce asexually via branched rhizomes, forming large clonal groups. It is a rustic species, able to withstand various environmental conditions. During winter, the leaves dry up, but as soon as the plant emerges from its vegetative rest, it sprouts new foliage.
Habitat
Native to North America.
Properties and Uses
P. cordata's attractive shape and colour make it an excellent ornamental plant. It also helps purify pond water by absorbing nutrients and carbon dioxide, acting as an effective natural filter in ponds with species such as crucian carp and carp, where high organic loads might otherwise promote the growth of unwanted filamentous algae. The plant is easy to grow and very resistant, requiring little special care.
The seeds are edible, whether raw or cooked, though they are best when roasted. The young leaves and stems can be eaten in salads, while the older leaves should be boiled before consumption.
Notes and Curiosities
In the Heller Botanical Garden, particular emphasis was placed on creating water bodies featuring aesthetically pleasing aquatic plants. Depending on whether they are free-floating or anchored to the ground—and on the water depth at which they thrive—these plants help recreate a seemingly natural environment. This habitat supports a rich array of animal life, including dragonflies, frogs, and other species typical of such ecosystems.
Among the many aquatic plants, P. cordata stands out with its striking purple spikes and bright green leaves. It plays a crucial role in purifying the water by acting as a natural filter. It is especially effective in ponds that host crucian carp and carp, where its nutrient uptake helps limit the growth of unwanted, filamentous unicellular algae.
Another member of the Pontederiaceae family present in the Heller Botanical Garden is the water hyacinth (Pontederia crassipes). Although both species are cultivated ornamentally, water hyacinth can become invasive if its growth is not controlled. In nature, water hyacinth has been introduced in many tropical and temperate regions as an ornamental plant. In the absence of natural competitors, herbivores, or parasites that normally limit their spread in their native habitats, it has become a serious ecological problem in several countries.