Tissues213-page13

Tissues213-page13 - Lenticel 3 Epidermal modifications of note • Hairs or Trichomes Many types for many purposes • Root hairs Absorption of H 2

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Plant Tissues - 13 2 . Periderm or Cork Produced from cork cambium and forms the secondary epidermis or periderm of woody plants Comprises, with phloem, the "bark" Functions for protection Periderm consists of cork (or phellem), cork cambium and phelloderm (parenchyma tissue interior to the cork cambium used for storage) Cork cells are produced exterior to the cork cambium, die at maturity, and contain suberin (non water soluble material) in their walls. Loose clusters of parenchyma cells are found within in the cork layer to permit gas exchange. These are called lenticels and are conspicuous in some species of trees. Cork cambium is dedifferentiated from a number of parenchyma cells, but typically from stem cortex parenchyma.
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Unformatted text preview: Lenticel 3 . Epidermal modifications of note • Hairs or Trichomes: Many types for many purposes • Root hairs: Absorption of H 2 O • Hairs reflect sunlight, lowering temperature and reducing water loss • Some hairs on salt marsh plants secrete salt • Hairs absorb water and minerals on above ground parts of plants • Hairs defend the plant against predators with barbs, traps, etc. • Guard cells Form stomata for gas exchange (Contain chloroplasts) • Glands Modified cells containing oils or other substances for secretion. Many glandular hairs contain toxins and irritants Glandular Trichomes Branched Trichomes Stomata and Guard Cells Root Hairs...
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This note was uploaded on 01/08/2012 for the course BIO 213 taught by Professor Makina during the Fall '09 term at SUNY Stony Brook.

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