MONTREAL -- Montreal’s botanical garden just unveiled a special type of pond — a natural effort to keep invasive species out of the park, an effort known as “phytotechnology.”

“Phytotechnology is a way to use plants to address environmental issues,” said Anne Charpentier, the garden’s director.

The pond is equipped with a self-contained system of water fed by a natural well that is underneath the garden. The plants in the pond occur naturally in Quebec, and the garden is trying to keep it that way.

The main target species that the Botanical Garden is trying to keep out is an invasive species called phragmites — a type of reed not native to North America.

“We have to control the plants and keep out the ones we don’t want,” said Curator Michel Labrecque.

One technique visible at the pond is floating islands of plants. Those islands choke light off from the pond bottom and help to prevent reeds and algae from blooming. Because the islands aren’t anchored, they can float around the pond freely, and they serve to add oxygen to the pond.

“The more oxygen you have in the water, the better water you have, and that limits the propagation of plants you don’t want,” Labrecque said.

The pond doesn’t use city water because it contains chlorine to make it drinkable.

Another similar feature in the garden is the presence of massive trees like willows that serve to add shade to the area.

The control of invasive species is also especially difficult at the garden due to the presence of two curations of foreign plants — the Chinese Garden and the Japanese Garden.

This is the second phytotechnology station the garden uses. Charpentier said she wants to create more in the future.