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Jan_19 - Body Plan of Higher Plants Basic structure of...

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Unformatted text preview: Body Plan of Higher Plants Basic structure of vascular plants reflects: – evolutionary history as terrestrial organisms – need to draw resources from below and above ground Variation in body plan: Variation e.g., golden barrel cactus e.g., Stem • Organ typically consisting of: – – terminal bud located near shoot tip alternating system of nodes, where leaves are attached and internodes, the segments between nodes petioles attaching leaf to stem axillary buds with potential to form lateral shoot, or branch – – – Modified Stems STRAWBERRY STOLONS ONION BULB Storage leaves ? stem ? roots ? POTATO TUBERS rhizome node GINGER RHIZOME roots Leaf Structure • Most monocots have parallel veins SIMPLE Petiole Axillary bud COMPOUND Leaflet • Eudicots have branching veins DOUBLY COMPOUND Petiole Axillary bud Leaflet Petiole Axillary bud Evolution of Modified Leaves TENDRILS SPINES STORAGE LEAVES BRACTS REPRODUCTIVE LEAVES Root System • Anchors the vascular plant • Absorbs minerals and water • Often stores carbohydrates & nutrients Common root system types tap roots Fibrous Modified Root Systems Prop Roots Storage Roots Aerial Roots Stilt Roots Buttress Roots Pneumatophores Plant Tissue Systems • Plant is characterized by cellular differentiation, the specialization of cells in structure and function • Each plant organ has dermal, vascular, and ground tissues • Connected systems of similar tissues throughout plant Dermal Ground Vascular Anatomy of a Leaf Let’s start with photosynthetic factories Let’s - Thin-walled cells with large water-filled vacuoles Thin-walled - Containing key energy-producing organelles Containing Mitochondrion Chloroplast Symmetry in Organelle Traits - Both have own DNA - Both self-replicate - Both have double-membrane Both - Both are apparent endosymbionts - And they share a symmetry in function . . . And Mitochondrion SUGAR Chloroplast CO2 KREBS CYCLE C3 CYCLE CO2 NAD+ NADH NADP+ NADPH e- ADP ATP ATP LIGHT ADP e1/2 O2 + 2H 1/2 O2 + 2H H2O Back to Leaf Anatomy We need to bathe cells in water We Back to Leaf Anatomy Surround them with epidermis (skin) And coat epidermis with a cuticle Leaf Anatomy But now we need to regain access to CO2 And we need to control water loss Leaf Anatomy By lining pores (stomates) with guard cells Leaf Anatomy Need to import water & export photosynthate Leaf Anatomy Add vascular bundle (xylem & phloem) Leaf Anatomy Finally, add some additional photosynthetic cells Finally, called palisade mesophyll Leaf Anatomy Palisade Mesophyll Cuticle Xylem Epidermis < 0.5 mm Guard Cells Phloem Spongy Mesophyll Bundle Sheath ...
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