1.   They were of modest size with an underground stem, but without spreading roots.

2.   He shakes most of the soil from their swollen underground stems and cuts the foliage and stems back to four-inch stumps.

3.   Instead it is a rhizome, an underground stem that grows sideways, rather than down, and has roots of its own.

4.   Its rhizomes, enlarged underground stems, are short.

5.   The plants spread by underground stems as they colonize.

6.   Some people believe compounds in the root and underground stem stimulate immunity and help fight colds and flu.

7.   White potatoes grow at the end of underground stems of the potato plant.