BIOL 1010 Lecture Notes - Lecture 61: Sieve Tube Element, Ground Tissue, Vessel Element
14 May 2017
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There are two types of sclerenchyma cells : fibre, and. Sclereids - fibre - long slender and usually arranged in bundles. Hemp is an example of a long fibre cell. Sclereids - shorter than fibre cells, they have thick irregular and very hard walls. (these cells impart the hardness in nutshells and grittiness of pears) Water conducting cells - tracheids long thin cells with tapered ends. Vessel elements wider shorter and less tapered. These cells are also arranged end to end, forming tubes as part of the phloem system. These cells remain alive once mature, but lose most organelles including the nucleus and ribosomes. This reduction allows nutrients to pass more easily through the cell. End walls between cells are known as the sieve plates, these wall have pores that allow fluid to flow from cell to cell. Along each sieve tube element is at least one companion cell. The companion cell is connected to the tube element by plasmodesmata.
