Plant anatomy

Plant anatomy - Organization of the plant body Growth form...

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Growth form (“body plan”) of plants is highly variable due to trophic specialization -- green plants can fix carbon via photosynthesis ( autotrophs ) -- some plants are parasitic or “feed” on organic debris life history: longevity, frequency of reproduction, etc. -- annual plants grow, reproduce once, and die quickly (yearly, or even more rapidly) -- perennial plants have long lives and reproduce repeatedly ecological specialization and habitat : trees, shrubs, vines, epiphytes (plants that grow on tree limbs), etc. However, most plants have common features of the “body plan”: overall body organization (major organs) tissue systems growth centers Organization of the plant body Organization of the plant body Plants have the same structural hierarchy as animals: Body is made of organs , which are built from different tissues , which in turn are made of different cell types . Three or four major organs: roots, stems, and leaves ( and flowers) Two growth ‘systems’: Shoot system: acquires light and CO 2 for photosynthesis; produces organic building blocks and energy; reproduction Root system: provides all nutrients except CO 2 , and support These let plants exploit two different environments, air and soil Vascular tissue Root system Flower Terminal bud (shoot apex) Node (leaf or branch attachment point) internode Terminal bud of branch Axillary bud Vegetative branch (no flowers) petiole Blade of leaf Lateral roots Shoot system ( stems , leaves, etc. ) Taproot (mainly in ‘dicots’) The plant body: Organs Flower Terminal bud (shoot apex) Node (leaf or branch attachment point) internode Terminal bud of branch Axillary bud Vegetative branch (no flowers) petiole Blade of leaf Lateral roots Root system Other modifications of leaves and stem: tubers (storage) stolon (“runners”: asexual reproduction) bulbs (underground shoot with leaves and stem) rhizomes (stems) cactus pads (stems) and spines (leaves) leaves used for flower enhancement The plant body: Organs Shoot system ( stems , leaves, etc. )
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Shoot system usually consists of nodes : points of leaf attachment or branching -- and internodes : stem segments between nodes. Terminal bud (at top of shoot) is primary growth region . Axillary buds at nodes generate lateral branches under certain condition (if terminal bud is removed or inhibited) Terminal bud Axillary buds node stem Terminal bud Axillary buds Branch terminal buds stem The plant body: Organs Similar node-internode pattern is repeated on branches internode Leaf morphology is also based on a simple structure; may be repeated to form a complex shape Two main components: petiole and blade Branch with terminal bud and axillary bud Simple leaf Compound leaf Doubly compound leaf leaflets The plant body: Organs Root cap at growing tip (secretes a lubricant to aid in growth through dense soil) The plant body: Organs Root hairs extend into soil; extensions of cell membrane and sites of water and nutrient uptake Roots are specialized for support and nutrient uptake must grow continuously
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This note was uploaded on 04/16/2008 for the course BIOL 5b taught by Professor Chappel during the Spring '08 term at UC Riverside.

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Plant anatomy - Organization of the plant body Growth form...

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