BIOA02H3 Lecture Notes - Lecture 4: Lignin, Vascular Bundle, Parenchyma
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The plant is eventually entirely sealed through bark (cork cells, now in multiple layers) In woody plants the epidermis of newly grown stems is replaced by the periderm later in the year. As the stems grow a layer of cells form under the epidermis, called the cork cambium, these cells produce cork cells that turn into cork. Xylem: tracheids => transportation and support, vessel members => transportation and support. Living at maturity: continuous system transporting water and minerals from roots to rest of the plant ( bottom-up) Vessel members: thick, lignified cell walls, elongated design, connected with a sort of twist and water is allowed to move through only through adjacent pits, relatively narrow, less rapid nutrient flow, dominant cell in gymnosperms. Softwood : cylinder as a design, connections much larger, wider, faster, more efficient, horizontal movement through pores, typically found more in angiosperms, Perforations and pits allow for movement more evolved than tracheids.
