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Chapter 21 Plant structure and function 21.1 Plant cells and tissues

Plant tissue Plant tissues are made up of three basic cell types: 1.) Parenchyma cells 2.) Collenchyma cells 3.) Sclerenchyma

Parenchyma cells Most common type of plant cell Stores starch, oil, and water for the plant Found throughout the plant Cells have thin walls and large water filled vacuoles in the middle Photosynthesis occurs in chloroplasts within parenchyma cells in the leaves Have the ability to divide throughout life span. Important for healing damage and regenerating parts

Collenchyma cells Cells range from thin to thick Provide support while still allowing plant to grow Most common in younger tissues of leaves and roots Often form strands…. Celery strings are strands of collenchyma Flexible and cells do not contain lignin Cells are stretchy and can change size

Sclerenchyma cells Strong cells These cells have a secondary wall that is hardened by lignin Very tough and durable So rigid they cannot grow with the plant Found in plant parts that are not lengthening anymore Most die when they reach maturity Form the major part of fruit pits and outer shell of nuts Gritty texture of pears are do to sclerenchyma cells

Tissue Systems 1.) dermal tissue 2.) ground tissue 3.) vascular tissue Just as three plant cells, there are three plant tissues 1.) dermal tissue 2.) ground tissue 3.) vascular tissue Plasmodesmata: strands of cytoplasm that pass through openings in cell walls and connect living tissue. *cells share water, nutrients, & chemical Signals through plasmodesmata

Tissue systems Dermal tissue: covers the outside of the plant and provides protection. Also known as epidermis Made up of live parenchyma cells in the non-woody parts On the leaves and stems – secretes wax that becomes the cuticle Dermal tissue made of dead parenchyma cells – outer bark of wood plants

Tissue systems Ground tissue: surrounded by dermal tissue and makes up much of the inside of a plant provides support and stores material in roots and stems In leaves: packed with chloroplast for photosynthesis Contains all three types of plant cells but parenchyma is by far the most common ground tissue

Tissue systems Vascular tissue: Surrounded by ground tissue, the system transports water, minerals, nutrients, and organic compounds to all parts of the plant Xylem: carries water and dissolved minerals Phloem: carries food from photosynthesis through out the plant