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The balloon­ shaped structures called tyloses

Correct answer: C. Are extensions of xylem parenchyma cells into vessels

  • A. Originate in the lumen of vessels
  • B. Characterise the sapwood
  • C. Are extensions of xylem parenchyma cells into vessels
  • D. Are linked to the ascent of sap through xylem vessels

Explanation

(c): Tyloses are balloon­like extensions of parenchyma cells that protrude into the lumen of a neighboring xylem vessel or tracheid through a pit in the cell wall. Tyloses form most commonly in older woody tissue, possibly in response to injury, they may eventually block the vessels and thus help prevent the spread of fungi and other pathogens within the plant. Tyloses may become filled with tannins, gums, pigments, etc., giving heartwood its dark color, and their walls can remain thin or become lignified.

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