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Unformatted text preview: –  tendrils of pea plants hMp:// Modified Leaves three >ssue systems •  Vascular system •  xylem – water and nutrient (mineral) transport from the roots •  Phloem – transport of carbohydrates from areas of produc>on (photosynthsis; primarily leaves) to rest of plant •  Dermal >ssue system •  protects against water loss (cu>cle) •  guard cells, forming stomata, are part of epidermal system •  ground >ssue system –  carries out photosynthesis –  support role, especially in growth how do plant cells divide? •  walls contain cellulose •  secondary walls may contain lignin how do plant cells communicate? diverse plant cell types general cell type, most numerous in young plants: parenchyma –  func>on as living cells •  photosynthe>c •  storage •  one other interes>ng cell type: sclerenchyma –  support cells, with thick secondary walls, oBen func>on in support aBer cell death •  two types •  fibers long cells, e.g. in hemp (Cannabis sa(vus) •  useful for rope, fabrics, ship sails •  made from hemp: Gutenberg Bible, the Declara>on of Independence, US Cons>tu>on, original Levi's blue jeans •  fibers also give tree bark its proper>es •  sclereids - e.g. stone cells in pear fruits •  Collenchyma elongated cells with thickened walls •  structurally support growing shoots and leaves •  e.g. the prominent strands in celery stalks •  oBen abundant in plants that are wind blown (can be induced by shaking the growing plant) •  walls made of cellulose and pec>n Celery. Light micrograph of a thinly sliced sec>on across a celery (Apium graveolens) stem. An epidermal layer (dark green) surrounds the soB watery interior (parenchyma >ssue). A semi- circle of vascular bundles (light and dark green ovals) supports the stem. These bundles contain xylem (holes in dark green >ssue) and phloem (light green) >ssue The phloem lies on the outer edges of the vascular bundles, between the xylem and the fibrous strands (collenchyma >ssue) that run down the stem surface. These structures make up the stringy part of celery. hMp://www.flic...
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