Plant Structures: Cells, Tissues, and Structures

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In reviewing plant physiology, plant cells are grouped into tissues based on similar characteristics, then into five distinct structures (organs).

  • Cells – individual building blocks for life processes and growth.  Common cells contain genetic matter (deoxyribonuecleic acid or DNA) and metabolic organelles but they are mostly water.  In green plants, they are the site of sugar production (photosynthesis).

plant cell

Figure 1.  Plant cell

  • Tissues – Groups of cells that are similar in appearance and function, for example:

  • Epidermis is the single exterior layer that protects the stems, leaves, flowers, and roots.  The outside surface of the epidermis tissue is usually covered with a waxy substance called cutin, which reduces water loss.

  • Parenchyma tissues are made of simple, thin-walled cells.  In a carrot, for example, the parenchyma cells become a storage unit called the cortex.  In leaves, a layer of parenchyma tissues under the epidermis is active in photosynthesis.  When wounded, parenchyma cells can become meristematic and proliferate to grow over the wound.

  • Meristematic tissues are comprised of actively dividing cells.

  • Sclerenchyma tissues are thick-walled support cells found throughout the plant as fiber.

  • Xylem is a structurally complex tissue that conducts water and nutrients from the roots to all parts of the plant.  The xylem is comprised of a series of long tubes made up of shorter vessel members.  In woody plants, the xylem tissue becomes the wood.

  • Phloem tissue conducts food and metabolites from photosynthesis throughout the plant, including down to the roots.

  • Structures (organs) – Groups of tissues working together with a common function, (e.g., roots, stems, leaves, flowers, fruits, and seeds).

  • Plant – Made up of a number of coordinated structures to form a working unit.

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Authors: David Whiting (CSU Extension, retired) with Michael Roll and Larry Vickerman (former CSU Extension employees). Artwork by Scott Johnson and David Whiting.

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Revised October 2014

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