Texas State University student Jamie Hand (Jamie Hand) leaned on the edge of her canoe and pulled out a dense, shiny green plant from the shore of the San Marcos River.

From spring to early autumn, large tracts of rivers are filled with this multifaceted troublesome plant: water hyacinth.

Here, it is an invasive species, crowding out native plants and disturbing the balance of the ecosystem. It multiplies rapidly, forming a mess of leaves, blocking sunlight-and ultimately oxygen-from entering the cold water below.

"It's like wine. A glass of wine is good, but two boxes of wine won't do much," said Sanchul Hwang, assistant professor of civil engineering at the Ingram School of Engineering.

In some places, aquatic plants have different reputations. When it is not busy with overcrowded waterways, plants can act as natural water purifiers, absorbing heavy metals and other pollutants through their roots. Huang said that some Asian countries even plant it for this purpose.

"That's the way it is. Water hyacinth [are] is actually nice and beautiful," he said. "But when they grow a lot, it's an environmental disaster."

Hwang and his students have been extracting and harvesting water hyacinth for the past few months. As part of their collaboration with HEDGE, a research team at Hwang began to upgrade invasive species to sustainable and functional materials.

One of their main projects is to turn water hyacinth into menstrual pads.

Hwang came up with this idea after meeting the river for the first time-there are many people, businesses, and of course water hyacinth. At the time, his teenage daughter started talking to him about global inequality related to menstrual hygiene and "menstrual poverty."

He combined what he saw by the river with what he heard from his daughter.

"She was actually the initiator of [the], or, you know, kind of reminded me of this project," he said.

In the HEDGE office, menstrual pads are nailed to the wall, almost like works of art. The wings of the cushions spread, and Ren Vogel jokingly called them "aircraft decorations."

“Sometimes, if we think about things like layers, we grab them off the wall,” said Vogel, a graduate student involved in HEDGE. "We will cut it open and look at it, for example, to understand how the manufacturer does it."

In the laboratory next door, she opened the stem of a dry water hyacinth.

"Whenever the water hyacinth dries, the inside becomes very fluffy and you can see the cell structure," Vogel said. "Look at that little one, it's a bit like a hexagon?"

This fluffy fibrous material is part of what makes plants so absorbent-and ideal for plant-based mats.

After harvest, the plants are cleaned and dried in an industrial-scale oven. Then mix the crunchy stems into a fine powder (vogel says it smells like apples) and mix it with raw cotton and water.

The result is a prototype that roughly resembles a panty lining, with speckled brown instead of bright white. This is just one layer-there will be several more layers in the final product.

"[The] in general is mainly to ensure that it is natural, user-friendly and biodegradable," Vogel said.

She said that removing invasive species from precious waterways like the San Marcos River is a victory in itself. But HEDGE wants to do more than just win.

"Our idea is to let us upgrade them instead of just harvesting them and dumping them in a landfill," Huang said. "This is—hey, let's do something with it. In particular, some things, some products, can be exploited or used in disadvantaged communities."

Although there are fewer water hyacinths along the San Marcos River at this time of year, there are many other invasive species: elephant ears, water lettuce, crocodile grass, and black algae.

"In the San Marcos area, there are too many invaders," Vogel said. "Invasive plants are the first global travelers, and they are one of the top five threats to biodiversity."

The challenge is to find a way to work with everyone—respect for their natural abilities, while still paying close attention to ensure that they do not cause serious damage to the natural balance of the ecosystem.

"You can do many things with plants," Vogel said.