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Download Plant Structure and Function Plant Cells and Tissues • Plant Cells
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Plant Structure and Function Plant Cells and Tissues • Plant Cells • Three basic types – Parenchyma – Collenchyma – Sclerenchyma Parenchyma • Loosely packed w/large central vacuole • Cubed – shaped or elongated • Involved in – Photosynthesis – Water storage – Nutrition or healing • Bulk of nonwoody plants • Fleshy parts of fruit Collenchyma • Thicker cell walls • Irregular shape • Support for plant Sclerenchyma • Thick, even, rigid cell walls • Support and strengthen plant • Dead at maturity – Hardness of shells around nuts Plant Tissue Systems • Dermal • Ground • Vascular Dermal Tissue • Forms outside covering – Epidermis – Parenchyma cells • Cuticle • Roots develop hair – like extensions • Stomata • Woody stems/roots replaced by dead cork cells (parenchyma) Ground Tissue • Surrounded by dermal tissue • All three types of plant cells • Make up majority of nonwoody plants • Main function – Storage – Metabolism – Support Vascular Tissue • Surrounded by ground tissue • Made up of – – • Xylem • Conducts water, mineral nutrients from roots upward • Provides structural support Phloem • Conducts organic compounds, some mineral nutrients • Alive a maturity Adapted to different environmental conditions – Xylem support and strength • May be absent in aquatic species Plant Growth • Flowering plants (Angiosperms) – Dicotyledons – Monocotyledons • • Gymnosperms – • Number of cotyledons or seed leaves in a plant embryo Have two or more cotyledons Monocot and Dicots Plant Growth • Originates in meristems – – • Continuous cell division • Apical meristem (primary growth, length) • Lateral meristem (secondary growth, diameter) Some monocots grow in length • Intercalary meristems • Located above the base of the leaves or stems (grasses) • Allows plants to regrow quickly after being grazed on Lateral Meristems – Gymnosperms and most dicots – Allow stems and roots to increase in diameter – Located outside of stem • Lateral Meristem • Two types – Vascular cambium • – Located b/w xylem and phloem Cork cambium • Located outside phloem • Produces cork • Replaces epidermis • Provides protection and prevents water loss Plants have three kinds of organs • Roots • Stems • Leaves Roots • Anchor the plant in the soil • Absorb and transport water and mineral nutrients • Storage for water and organic compounds Types of Roots • • Taproot – Primary root – Rarely more than one – two meters Fibrous root system – • Numerous small roots Adventitious roots – Specialized roots grow from other places – Leaves and stems – corn and epiphytic orchid (aerial roots) Root Structures • • Root cap – Covers apical meristem – Produces oil Root hairs – Extensions of epidermal cells – Increase surface area • Dependent on stems and leaves for energy • Store starch • Primary Growth in Roots • Increase length through cell division of the apical meristem • Dermal tissue matures for form the epidermis • Ground tissue matures into • • – Cortex – Endodermis Large portion of the root is made up of parenchyma cells – Endodermis – Inner most boundary of cortex – Semipermeable membrane (waxy layer) – Controls the flow of dissolved substances Vascular tissue – Makes up innermost core of root – Dicots and gymnosperms – • • Xylem makes up central core • Usually forming an X • Pockets of phloem b/w lobes Monocots • Xylem occurs in patches that circle the pith (parenchyma) • Phloem occurs b/w the xylem patches Outermost layer of vascular tissues – Pericycle – Form lateral roots
