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Unformatted text preview: em cells. Secondary growth makes stems and
roots grow thicker.
• Cells differentiate to form the three major tissue types:
• Dermal tissue: covers the outer surface of plants
• Vascular tissue: pipelines that transport water, dissolved minerals, and sugars
• Ground tissue: Just about everything else; tissues that carry out photosynthesis, storage, and support.
• Dermal tissue:
• Epidermis: the “skin” of the plant, often as thin as one cell layer. May have a waxy cuticle layer on top,
and may have various hairs growing out of it. (Cotton is a type of hair growing out of the epidermis of
the seeds of the cotton plant.)
• Periderm: composed of a layer of cork cells, forms the outer covering of roots and stems in woody
plants, and the outer layer of bark.
• Ground tissue: The “-enchyma” triplets
• Parenchyma: thin-walled cells, alive at maturity, with many different functions, including photosynthesis,
food storage, hormone production. Examples: the fleshy parts of edi...
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