Which of the following describes a rhizome?

A rhizome is correctly described as a horizontal underground stem that produces shoots and roots. This type of stem grows horizontally rather than vertically and serves several functions in plants, such as storage of nutrients and vegetative reproduction. Unlike roots, which primarily absorb water and nutrients from the soil, rhizomes can give rise to new shoots and thereby contribute to the growth of the plant. This allows for the plant to spread and colonize new areas.

The definition emphasizes that rhizomes are stems, distinguishing them from roots and other structures. Additionally, they can produce new shoots that result in new growth above the ground, showcasing their role in plant propagation. This aspect makes them particularly important for plants that reproduce vegetatively.

The other descriptions do not accurately encapsulate the characteristics of a rhizome, each referring to different plant structures, such as roots (which are primarily for nutrient uptake), or seed structures (which are related to plant reproduction through fertilization rather than vegetative growth).