Chapter 8: The Leaf and its Function PDF

Chapter 8 The Leaf and its Function  Leaves are the plant organs that take part in photosynthesis and transpiration. Bio. Sci 1. – General Botany  Leaves...

Chapter 8 The Leaf and its Function  Leaves are the plant organs that take part in photosynthesis and transpiration. Bio. Sci 1. – General Botany  Leaves Leaves are the principal structure, produced on stems, where photosynthesis takes place. Leaves convert light energy to chemical energy. Leaves are the main photosynthetic organs of most plants. Bio. Sci 1. – General Botany  Functions Manufacture food through photosynthesis Gas (Air) Exchange – Respiration Protect vegetative and floral buds Water Transport – Bio. Sci 1. – General Botany Gross Struct ure of  Gross Structure of Leaf Lamina – the expanded leaf blade (Lamina Petiole - slender stalk Stipules - outgrowths Bio. Sci 1. – General Botany  Gross Structure of Leaf Midrib – central conducting and supporting (Lamina structure of the blade. Veins – network arising from the midrib. Bio. Sci 1. – General Botany  Gross Structure of Leaf Leaflet – distinct and separate segment of a compound leaf. Petiolule – stalk of a leaflet Rachis – main axis of a pinnately compound leaf. Bio. Sci 1. – General Botany  Gross Structure of Leaf Pulvinus – swollen base of a petiole or petiolule. Bio. Sci 1. – General Botany Microsco pic Structur  Microscopic Structure of Leaf Cuticle – outermost layer of both the upper and lower surfaces of the leaf. Clear and waxy to prevent water loss. Epidermis – thick layer of cells that provides protection for the inner tissues. Mesophyll – between the epidermal layers where photosynthesis takes place. Stomata – openings in the surface of the leaf and stems for gas exchange. Bio. Sci 1. – General Botany  Microscopic Structure of Leaf Veins – Contains the vascular tissue (Xylem and Phloem). Vascular Bundle – Strand of specialized vascular tissue of higher plants consisting mostly of xylem and phloem. Bundle Sheath – Compact layer of commonly parenchymatous cells forming a sheath around a vascular bundle. Bio. Sci 1. – General Botany  Simple vs. Compound Leaves Simple Leaves Compound Leaves When the blade is When the blade consists of a single piece of two or more separate parts on a common Bio. Sci 1. – General Botany  Compound Leaves Palmately Pinnately Bi-pinnately Compound Compound Compound Leaflets are Leaflets radiate Leaflets arranged compound with from Bio. Sci 1. – Generalone Botany central on both sides of a smaller leaflets on  Phyllotaxy or Leaf Arrangement Bio. Sci 1. – General Botany  Leaf Arrangement Alternate Opposite Whorled Characterized by Characterized by Characterized by only one leaf at two leaves in one three or more each node. node. leaves per node. Bio. Sci 1. – General Botany  Alternate Type Distichous Secund Spiral 1 leaf per node 1 leaf per node 1 leaf per node but arranged in but arranged in 1 but arranged in two rows when direction only. spiral form. viewed on top. Bio. Sci 1. – General Botany  Opposite Decussate 2 leaves per node but arranged in four direction. Bio. Sci 1. – General Botany  Rosette Rosette Leaves arranged tightly at the plant crown. Bio. Sci 1. – General Botany  Leaf Venation Bio. Sci 1. – General Botany  Leaf Venation Parallel-veined leaves Netted-veined or Consists of slender ribs or reticulate leaves veins that run parallel to Veins branch and rebranch each other. into finer veinlets which unite to form meshes. Bio. Sci 1. – General Botany  Netted-veined or reticulate leaves Pinnate Palmate Has 1 midrib Several large veins of equal size branch into the blade from the end of Bio. Sci 1. – General Botany the petiole.  Leaf Margin Bio. Sci 1. – General Botany  Leaf Margin Entire Serrate Continuous even line Margin are cut into margin, without teeth or sharp teeth pointing notches. forward like the teeth of the saw. Bio. Sci 1. – General Botany  Leaf Margin Dentate Crenate Leaf has triangular or tooth- Leaf edge has blunt, like edges. rounded teeth. Bio. Sci 1. – General Botany  Leaf Margin Undulate Sinuate Margin forms a wavy Margins are slightly line bending gently wavy. inward and outward. Bio. Sci 1. – General Botany  Leaf Margin Incised Lobed Leaf margins have deep, Margin are deeply cut, but the irregular teeth. incisions do not reach much Bio. Sci 1. – General Botany more than halfway to the  Leaf Shape Bio. Sci 1. – General Botany  Leaf Shape Linear Lanceolate Oblong Leaves are Widest below and Not narrow and taper upward. conspicuously margins are Shape like lance. narrowed. Sides nearly parallel. are parallel. Bio. Sci 1. – General Botany  Leaf Shape Oval Cordate Leaves widest in the Heart-shaped middle, tapering on both ends. Bio. Sci 1. – General Botany  Leaf Modification Bio. Sci 1. – General Botany  Bud Scales Overlapping modified leaves which protect the growing tissues of buds of most plants. Maple Twig Bio. Sci 1. – General Botany  Spines Protect the plant from grazing animals and other enemies. Leaves of Cactus Bio. Sci 1. – General Botany  Water Storage Leaves Fleshy structures with thick layer of cutin serving for the storage of water. Cobweb houseleek Bio. Sci 1. – General Botany  Tendrils Used for climbing Bitter Gourd Bio. Sci 1. – General Botany  Insect trapping leaves Attract, capture, and digest insects which supplement their nutritional needs. Pitcher plant Bio. Sci 1. – General Botany  Reproductive leaves Perform reproductive processes. Red petals of poinsettia Bio. Sci 1. – General Botany  Leaf Physiological Process Bio. Sci 1. – General Botany The process which plants use the energy from sunlight to produce sugar.  Stage 1: Energy is captured from sunlight  Stage 2: Light energy is converted to chemical energy.  Stage 3: Chemical energy powers formation of organic compounds using CO2 Bio. Sci 1. – General Botany Bio. Sci 1. – General Botany  Respiration Sugars produced by photosynthesis are used directly in respiration. The release of the energy derived from the food created by photosynthesis.  Aerobic Respiration – occurs only in the presence of oxygen.  Anaerobic Respiration – occurs only under special circumstances such as the absence of oxygen. Bio. Sci 1. – General Botany Photosynth esis  Transpiration The process of water loss in the form of water vapour. Elimination of excess water from the plant body Bio. Sci 1. – General Botany  Stomatal Mechanism OPEN : during the day CLOSED : at night Stomata closed to prevent water loss Sunny day : demand for CO2 in leaf is high, stomata is wide open. Bio. Sci 1. – General Botany Translocati Sugar on https://media.springernature.com/lw685/springer-static/image/chp%3A10.1007%2F978 3-319-79099-2_16/MediaObjects/436477_1_En_16_Fig1_HTML.gif  https://www.vocabulary.com/dictionary/leaf#:~:text=A%20leaf%20is%20part%20of,spring% 2C%20trees%20grow%20new%20leaves. https://www.thoughtco.com/thmb/7EhnD-bDXTtLZcnenaSlA8dE6-k=/1500x0/filters:no_upscal e():max_bytes(150000):strip_icc()/parts_of_a_leaf-56abaed23df78cf772b5625a.jpg https://www.carlsonstockart.com/images/xl/Leaf-Structure_labeled.jpg https://orbisec.com/wp-content/uploads/2014/10/Leaf-Arrangement.gif https://cdn.plantatlas.org/img/specimens/USF/257976.jpg https://qph.cf2.quoracdn.net/main-qimg-5dd452aff2b9b1eadd51aa0d089598c7-lq https://ilovelearningscience.files.wordpress.com/2015/04/net-or-parallel-veins.png https://etc.usf.edu/clipart/4800/4830/parallel-veined-leaf_1_lg.gif https://l450v.alamy.com/450v/2ax564k/the-elements-of-botany-for-beginners-and-for- schools-ed-and-the-mtted-veined-127-in-netted-veined-also-called-reticulated-leaves-the- veins-branchoff-from-the-main-rib-or-ribs-divide-into-finer-and-finer-veinlels-and- thebranches-unite-with-each-other-to-form-meshes-of-network-that-is-theyanastomose-as- anatomists-say-of-the-veins-and-arteries-of-the-body-thequince-leaf-in-pig-112-shows-this- kind-of-veining-in-a-leaf-with-a-singlerib-the-maple-basswood-plane-or-buttonwood-pig-74- show-it-inleaves-of-several-ribs-128-in-parallel-veined-leaves-the-whole-framework-consists- o-2ax564k.jpg https://byjus.com/biology/difference-between-stem-tendril-and-leaf-tendril/#:~:text=Stem%2 0tendrils%20are%20branch%20modifications,gets%20modified%20into%20a%20tendril. https://byjus.com/biology/transpiration/#:~:text=This%20process%20of%20elimination%20o f,aerial%20parts%20of%20the%20plants.