rhizome or rootstock, fleshy, creeping underground stem by means of which certain plants propagate themselves. Buds that form at the joints produce new shoots. Thus if a rhizome is cut by a cultivating tool it does not die, as would a root, but becomes several plants instead of one, which explains why such weeds as Canada thistle and crabgrass are so hard to eradicate. Ginger, the common iris, trillium, and Solomon's-seal all have rhizomes. True arrowroot is starch from the rhizome of a West Indian plant. See perennial.

Horizontal underground plant stem capable of producing the upward shoot and downward root systems of a new plant. This capability allows vegetative (asexual) propagation and enables plants to survive an annual unfavourable season underground. In some plants (e.g., water lilies, many ferns, and forest herbs), the rhizome is the only stem of the plant. In such cases, only the leaves and flowers are readily visible.

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