The aboveground parts die and break off, forming floating mats.

It grows rapidly and forms dense mats over still waters.

It may form mats nearly a metre wide and up to 40 cm tall.

It has one or more stems up to 20 centimeters long and may form mats.

It may form large interwoven mats over the water or along shorelines.

It is a spreading plant which forms dense green mats on the ground.

The plant germinates in fall or late winter, then forms large mats of foliage.

It can form dense mats and even mounds that grow over low features.

In late Winter it can form large mats on the bottom of rivers and streams.

Both grasses form thick mats if they're properly cared for.