Rhizodermis

Part of speech: noun

Definitions

1. The outer cellular layer of a plant root that directly absorbs water and dissolved nutrients from the soil
2. The epidermis of a root, consisting of specialized cells that take up water and minerals for the plant
3. The outermost tissue layer of a root responsible for absorbing water and mineral nutrients from the ground

Etymology: Plant anatomists needed a name for the outer layer of a root, and they built one from two Greek nouns: "rhiza," meaning root, and "derma," meaning skin. It is a plain technical compound, the root's counterpart to the epidermis that covers a leaf or stem. The same "rhiza" appears in "rhizome," the creeping underground stem of plants such as ginger and iris, and in "rhizobia," the bacteria that form nodules on the roots of legumes. "Derma" gives English "dermatology" and "dermis," the layer of animal skin beneath the epidermis.