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Plant Anatomy. Basic Plant Anatomy. root root tip root hairs shoot (stem) nodes internodes buds terminal or apical buds axillary buds flower buds & flowers leaves mesophyll tissue veins (vascular bundles). Leaves. Function of leaves photosynthesis energy transformation
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Basic Plant Anatomy • root • root tip • root hairs • shoot (stem) • nodes • internodes • buds • terminal or apical buds • axillary buds • flower buds & flowers • leaves • mesophyll tissue • veins (vascular bundles)
Leaves • Function of leaves • photosynthesis • energy transformation • organic matter production • gas exchange • transpiration simple vs. compound
Modified leaves tendrils (peas) spines (cacti) succulent leaves colored leaves (poinsetta)
Interdependent Systems • Both systems depend on the other • roots depend on sugars produced by photosynthetic leaves • shoots depend on water & minerals absorbed from the soil by roots sugars water &minerals
Plant TISSUES • Dermal • epidermis (“skin” of plant) • single layer of tightly packed cells that covers & protects plant • Ground • bulk of plant tissue • photosynthetic mesophyll, storage • Vascular • transport system in shoots & roots • xylem & phloem
Vascular tissue vessel elements • Xylem • move water & minerals up from roots • dead cells at functional maturity • only cell walls remain • need empty pipes to efficiently move H2O • transpirational pull vessel element dead cells Aaaah… Structure–Functionagain! tracheids
Phloem: food-conducting cells • carry sugars & nutrients throughout plant sieve tube companion cell sieve plate plasmodesmata living cells
Aaaah… Structure–Functionagain! Phloem • Living cells at functional maturity • cell membrane, cytoplasm • control of diffusion • lose their nucleus, ribosomes & vacuole • more room for specialized transport of liquid food (sucrose) • Cells • sieve tubes • sieve plates — end walls — have pores to facilitate flow of fluid between cells • companion cells • nucleated cells connected to the sieve-tube • help sieve tubes
Phloem: food-conducting cells • sieve tube elements & companion cells
Growth in Plants • Specific regions of growth: Meristems • Stem cells: perpetually embryonic tissue • Regenerate new cells • Apical shoot meristem • growth in length • primary growth • Apical root meristem • growth in length • primary growth • Lateral meristem • growth in girth • secondary growth
Apical meristems shoot root
Primary xylem Growth in Woody Plants Primary phloem • Woody plants grow in height from tip • primary growth • apical meristem • Woody plants grow in diameter from sides • secondary growth • lateral meristems • vascular cambium • makes 2° phloem & 2° xylem • cork cambium • makes bark Epidermis Lateral meristems Secondary xylem Primary phloem Primary xylem Secondary phloem Annual growth layers Bark
Secondary Growth • Secondary Growth • growth in diameter • thickens & strengthens older part of tree • cork cambium makes bark • growing ring around tree • vascular cambium makes xylem & phloem • growing ring around tree