Study GuidePlant Biology–Roots1. Primary Root Tissues and StructureTheprimary roothas a simpler tissue arrangement than theprimary stem. This is because roots donot produce leaves, so they do not need side connections to the vascular system. As a result, theirinternal structure is more straightforward.Theprimary plant bodyof the root is formed by three primary meristems and has three mainregions:1.Epidermis–the outer protective layer2.Cortex–a broad middle region mainly for storage3.Stele (vascular cylinder)–the central conducting region1.1EpidermisTheepidermisis the outermost layer of the root. In young roots, many epidermal cells formroothairs.Why root hairs are important:•They greatlyincrease surface area•This allows morewater and mineral absorption•Each root hair is an extension of theprotoplast(living cell content)Root hairs:•Havevery thin walls•Areextremely delicateand easily broken•Live only for a short timeIn some plants, the root epidermis is covered by athin waxy cuticle. This layer is not thick enough toblock the movement of water and dissolved substances into the root.Preview Mode
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