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Chapter 23: Roots, Stems, and Leaves

Chapter 23: Roots, Stems, and Leaves. The three principle organs of seed plants. Roots absorb water and dissolved nutrients a nchor plants in the ground h old plants upright through wind and rain Stems support the plant t ransports nutrients to the rest of the plant

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Chapter 23: Roots, Stems, and Leaves

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  1. Chapter 23: Roots, Stems, and Leaves The three principle organs of seed plants • Roots • absorb water and dissolved nutrients • anchor plants in the ground • hold plants upright through wind and rain • Stems • support the plant • transports nutrients to the rest of the plant • compete for sunlight by holding leaves higher • Leaves • are the principle organ for photosynthesis • have broad, flat surfaces, inc S.A. for sunlight • pores conserve water and allow gas exchange

  2. Meristem Tissue Stem The only plant tissue that produces new cells by mitosis Root Apical meristem is found at the tips of stems and roots.

  3. Tissue Systems • Plants consist of 3 tissue systems: • Dermal tissue – outermost layer; forms the “skin” of the plant • Vascular tissue – transports water & nutrients; “bloodstream” • Ground tissue – tissue between the dermal and ground tissues

  4. Dermal tissue – generally consists of a single layer of epidermal cells. The outer layer is often covered with a thick, waxy layer called the cuticle, which protects against water loss and injury. Vascular tissue – contains several different cell types; transporting water and nutrients around the plant. Ground tissue – cells that lie between the dermal and vascular tissues.

  5. Roots Roots absorb water and dissolved nutrients from the soil. Plants have a one-way system to generate enough pressure to move water out of the soil and into the body of the plant. The water has no where else to go, but UP! Root hairs increase surface area! Fibrous roots Tap roots

  6. Stems • Stems have 3 important functions: • Produce leaves, branches and flowers • hold leaves up in the sunlight • transport substances between roots and leaves Leaves are attached to a stem at structures called nodes. Some stems can also carry out photosynthesis

  7. Formation of Wood Read p. 592 The most important “stem” is the stem of the tree. Wood is actually layers of xylem!

  8. Leaves Transpiration – The loss of water from a plant through its leaves Maple tree leaves Black Walnut tree leaves

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