rhizome

This stem is called a rhizome.

In fall, she cuts the leaves down to about 6 inches above the rhizome.

“My dream as a teacher,” Haas said, “is when something keeps growing underground, like a rhizome, and then at a different place grows into a different plant.”

Only the blechnum seemed not to have weathered the agonizing collapse: When Baer cut a sample for analysis, he could find no trace of healthy rhizome, or fern stem, as the other plants had.

The plant gets its common and genus names from the blood-red fluid that exudes from every part of the plant, including the underground rhizome, when cut.