Anatomy and Physiology of Plants: From Seeds to Roots, Stems, and Leaves, Essays (university) of Science education

Download Anatomy and Physiology of Plants: From Seeds to Roots, Stems, and Leaves and more Essays (university) Science education in PDF only on Docsity! PLANTS THE PLANT BODY shoot tip (apical buddy EPIDERMIS lateral bud node internode node primary root lateral root root hairs root tip root cap Evolution of Plants (Cladogram) Flowering plants Cone-bearing plants Ferns and their relatives Mosses and their relatives Green algae ancestor Flowers; Seeds Enclosed in Fruit Seeds Water-Conducting (Vascular) Tissue Adaptations of Plants to Land  Seeds (Dormant until water added)  Roots  Stems  Leaf – Autotrophic Organisms  Must Conserve Water (Stomata)  Reproductive Strategies Roots, Stems, and Leaves Plant Tissues 1. The Seed  External Structures  1. Seed coat  2. Hilum  3. Micropyle  Internal Structures  1. Embryo plant  2. Cotyledon Germination – To Begin to Grow 2. Roots: Anchors Away  Functions  Anchors the plant  Absorbs water and minerals from soil  Stores food Secondary Roots  Develop from the primary root and from themselves. Tap Root System  Develops from the primary root.  Reaches deep into the ground  Helps the plant during periods of drought. Fibrous Root System  Develops when the secondary roots become the main roots.  Shallow roots but spread over a broad area.  Helps prevent erosion. 2 MONOCOTYLEDONOUS & DICOTYLEDONOUS FLOWERING PLANTS Monocots and Dicots Examples 9 MD Sm OQ: usually bundies root parts - parallel usually eyetens usually in complexiy multiples: areerngpexd of three % Pa aor’ rE Sees aterone] eh e a at DicoTs ~3< < ‘ =a olf fs 2 < . — Wascular Taproot Floral Two See caaa bu - cotyledo: usual usually in 5 mae present ty" . in ring of four Grasses Lilies orchids Palms Oaks Bean Spinach Rose  MONOCOT ROOT IN CROSS SECTION ‘Copyright The McGraw-Hill Companies, inc. Permission required tor reproduction or disptay. Monocot root epidermis cortex endodermis pericycle Primary phloem Primary xylem pith suberized endodermis endodermis ‘casparian strip (band around endodermis) EPIDERMIS Outer layer of cells ("skin")  Protection against dehydration, bacteria or virus CORTEX  Region between epidermis & vascular cylinder  Supports plant parts & stores food  Made up of parenchyma cells ( thin layer, loosely packed with large intercellular spaces that provides aeration for the cells )  Plasmodesmata are channels in the parenchyma cells which allows water to enter from one cell to the other ENDODERMIS  Layer of cells just outside vascular cylinder.  Waterproof band or strip that regulates the flow of water in the xylem PERICYCLE  Cylindrical layer of cells inside endodermis  Origin of cork & secondary (side) roots  Undergo cell division which produce lateral growth LATERAL ROOTS ARISE FROM THE PERICYCLE SECONDARY GROWTH IN DICOT ROOTS epidermis cortex endodermis pericycle procambium Primary xylem Primary phloem wascular cambium produced by pericycle wascular cambium produced by procambium secondary xylem secondary phloem PHLOEM  Living (inner) vascular system carrying dissolved sugars and organic compounds throughout plant. XYLEM  Living (outer) vascular system carrying water & minerals throughout plant. Path af water aSparian strip. endodermis pericycle cortex @pidermis Path of water 3. Stems: The Connector  Functions  Connects the leaves with the roots  Displays the leaves for maximum sunlight exposure.  Stores food  Minor photosynthetic ability  Contains vascular tissue  Phloem – transports sugars from leaves  Xylem – transports water and minerals from roots Stem  one of two main structural axes of a vascular plant, the other being the root.  normally divided into: nodes and internodes: Nodes  hold one or more leaves, as well as buds which can grow into branches (with leaves, conifer cones, or inflorescences(flowers).   Adventitious roots may also be produced from the nodes. Types of Stems  Herbaceous: softer texture stems that die at the end of the growing season; non- woody.  Woody: hard textured stems with secondary xylem  Woody stems longer than 5m with a trunk make the plant a tree. Dicot Stems  Pith in the center  Outside of stem is still the epidermis  Lateral growth is due to the vascular bundles in a ring Dicot Stems IF WOODY STEM:  Each vascular bundle has a meristem between the xylem and phloem  Secondary xylem grows to the inside, while secondary phloem grows to the outside  The epidermis and cortex get destroyed as the secondary xylem and phloem grow. Specialized Stems  Bulb: short underground stem with fleshy leaves attached (tulip, onion, daffodil)  Climbing: stems that cling to or wrap around other plants or structures (ivies, vines) SPECIALIZED STEMS =m Spur-short, slow-growing stems that bear leaves, flowers, or fruit. m Prickle —a sharpened extension of the stem's outer layers (roses) mw Peduncle —a stem that supports an inflorescence Specialized Stems  Corm: short, enlarged, underground stem (gladiolus, crocus)  Rhizome: a horizontal, underground stem used mainly in reproduction, but also in storage (ferns, iris) A. Vascular cambium appears B. Secondary growth continues C. Mature stem develops Epidermis Cortex Primary phloem Vascular cambium Primary xylem Pith Secondary phloem Secondary xylem Cork Cork cambium Primary phloem Secondary phloem Secondary xylem Primary xylem Bark Wood  Secondary Growth in Stems Wood Bark Cork Cork Cambium Phloem Vascular Cambium Xylem: Sapwood Xylem: Heartwood  Layers of a Tree Trunk Contains old, nonfunctioning xylem that helps support the tree Contains active xylem that transports water and minerals Produces new xylem and phloem, which increase the width of the stem Transports sugars produced by photosynthesis Produces protective layer of cork Contains old, nonfunctioning phloem that protects the tree 4. Leaf - Autotrophic  Functions  Carries on Photosynthesis  Stores food  Regulates transpiration through stomata Sugar Transport in Phloem Nutrient ‘Transport # Occurs in PHLOEM ™ Pressure-flow hypothesis 5. Water Conservation  Cuticle  Waxy outer coating that prevents water loss  Stomata  Openings for gas exchange  Open to release water, Close to conserve Section 23-4 Stoma Open Stoma Closed Guard cells Inner cell wall Stoma Guard cells Inner cell wall Section 23-4 Stoma Open Stoma Closed Guard cells Inner cell wall Stoma Guard cells Inner cell wall Water Transport