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Induced by shaking the growing plant

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Unformatted text preview: kr.com/photos/ 36669804@N06/3892339473 evolu>on of xylem in angiosperms •  •  •  •  •  •  •  •  •  non- angiosperm vascular plants: tracheids become func>onal aBer programmed cell death (apoptosis) conduct water through pits connec>ng tracheids angiosperms vessel elements are the main xylem cell many angiosperms also have tracheids also go through apoptosis before func>oning have larger diameters than tracheids form hollow tubes end- to- end that conduct water more efficiently than tracheids angiosperm phloem •  transpor>ng cells in phloem system func>on as living cells •  sieve tube elements transport carbohydrates •  sieves are connec>ons with enlarged plasmodesmata •  sieve tubes are full of phloem sap (water plus dissolved carbohydrates and other molecules) •  lose their organelles as sieve holes expand •  companion cells, connected with sieve tube cells via plasmodesmata •  retain their organelles and support the sieve tube cells modules and meristems plant bodies are organized into modules module = node + aMached leave(s) + internode below the node + axillary bud(s) at internode base •  each branch is a module •  leaves are a different type of module •  root organiza>on is branching but node organiza>on not as obvious •  many lateral branching roots are independent, can explore new area with growth aBer other roots have died •  “primary” and “secondary” plant bodies –  primary = living and growing part –  secondary = dead, support part (woody) –  most monocots primary only •  •  meristems of the primary plant body`...
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