Plant Structure, Growth and Development - Biology for Science Majors II - Lecture Slides, Slides of Biology

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Chapter 35 Plant Structure, Growth & Development Flowering plants: 2 main groups Monocots: Eudicots: See Fig. 30.12 Organ systems of flowering plants See Fig. 35.2 Leat { Flower Terminal bud (shoot apex) Node Internode Axillary bud Terminal bud of branch Vegetative branch Petiole Blade Stem Taproot — Lateral roo > Shoot system >Root system as Primary root – first to appear Eudicot Taproot system Monocot Fibrous root system Organs of flowering plants Root hairs are extensions of epidermal cells Organs of flowering plants Aboveground (aerial or prop) roots give extra support Organs of flowering plants “Breathing” roots conduct oxygen to waterlogged roots Organs of flowering plants The roots of many orchids are photosynthetic Organs of flowering plants Organs of flowering plants Stolons (“runners”) are horizontal, wandering, aboveground stems Organs of flowering plants Rhizomes (e.g., edible base of a ginger plant) are horizontal, belowground stems Organs of flowering plants Tubers (e.g., potatoes, yams) are the swollen ends of rhizomes, specialized for food storage Organ systems of flowering plants Terminal buds generally exercise apical dominance over axillary buds See Fig. 35.2 Organs of flowering plants Leaflet \ Axillary bud Axillary bud Simple leaf Compound leaf Doubly compound leaf See Fig. 35.6 Organs of flowering plants Some arid-adapted plants have succulent leaves Aloe vera Organs of flowering plants Leaves specialized to trap animals occur in carnivorous plants Organs of flowering plants Leaves specialized to trap animals occur in carnivorous plants Organs of flowering plants Leaves specialized to trap animals occur in carnivorous plants Organ systems of flowering plants When a cell divides, the daughter cells grow… and they may differentiate (specialize), depending especially on where they are located during development See Fig. 35.2 Differentiated cells contribute to 3 tissue systems Dermal tissue (epidermis) Generally a single cell layer that covers the plant Absorption in root system Water retention in shoot system, aided by waxy cuticle See Fig. 35.8 Differentiated cells contribute to 3 tissue systems Vascular tissue Xylem – transports water and dissolved minerals Phloem – transports sugars dissolved in water See Fig. 35.8 Differentiated cells contribute to 3 tissue systems Ground tissue All non-epidermal, non- vascular tissue Three principal cell types: Parenchyma Collenchyma Sclerenchyma See Fig. 35.8 Differentiated cells contribute to 3 tissue systems Ground tissue Parenchyma • Thin-walled, live cells • Perform most metabolic functions of plant – photosynthesis – food storage – synthesis and secretion Differentiated cells contribute to 3 tissue systems Ground tissue Collenchyma • Cells with unevenly thickened walls that lack lignin • Alive at maturity • Grouped into strands or cylinders to aid support without constricting growth Primary growth in roots The apical meristem produces three primary meristems See Fig. 35.12 Primary growth in roots The cells are produced… See Fig. 35.12 Primary growth in roots The cells are produced… then elongate… See Fig. 35.12 Primary growth in roots The cells are produced… then elongate… Protoderm cells become the epidermis Ground meristem cells become the cortex See Fig. 35.12 Primary growth in roots The cells are produced… then elongate… and finally mature & differentiate Protoderm cells become the epidermis Ground meristem cells become the cortex Procambium cells become the vascular stele See Fig. 35.12 Primary growth in roots Pericycle Outermost layer of stele These cells retain meristematic capabilities, and can produce lateral roots See Fig. 35.12 Primary growth in shoots Primary growth in shoots lengthens shoots from the tips The apical meristem produces the same three primary meristems as in the roots: Protoderm Ground meristem Procambium See Fig. 35.15 Primary growth in shoots Primary growth in shoots lengthens shoots from the tips Leaves arise from leaf primordia on the flanks of the apical meristem See Fig. 35.15 Primary growth in shoots Primary growth in shoots lengthens shoots from the tips Axillary buds (that could produce lateral branches) develop from islands of meristematic cells left at the bases of leaf primordia See Fig. 35.15 Primary growth in shoots Procambium cells develop into vascular bundles The “veins” in leaves Primary growth in shoots Protoderm cells develop into epidermis See Fig. 35.17 Primary growth in shoots Protoderm cells develop into epidermis Some epidermal cells are guard cells surrounding stomata See Fig. 35.17 Primary growth in shoots Ground meristem cells develop into ground tissues In dicot stems these are the pith and cortex See Fig. 35.16 Ra initials Secondary growth in stems gs Girth growth Pan — Hh . Primary xylem —— Vascular cambium —— Primary xylem Vascular cambium Primary phloem Primary phloem —— ‘Cort ex Phicem ray grow -_ 9 Xylem ray ake Primary xylem Secondary xylem Vascular cambium Secondary phloem . co Primary phicem cambium Late wood ait 0 Early wood co ae 9 Pith Primary xyle Secondary xylem Secondary xylem (two years of production) Vascular cambium Secondary phloem Vascular cambium Secondary phloem @ Cork cambium See Fig. 35.18 @cork © Periderm Copyright & Pearson Education, Inc,, publishing as Benjamin Cummings. Secondary growth in stems Primary growth at a branch tip lays down apical and axillary meristems for further lengthening, as well as a lateral meristem: the vascular cambium See Fig. 35.18 Secondary growth in stems As the stem continues to expand its girth, the tissues outside the cork cambium rupture and slough off See Fig. 35.18 Secondary growth in stems As the stem continues to expand its girth, the cork cambium reforms in deeper layers of cortex tissue, and then in secondary phloem when the primary cortex is gone See Fig. 35.18 Secondary growth in stems Periderm: Cork cambium and cork Bark: All tissue outside vascular cambium See Fig. 35.18 Why do trees have rings? Seasonal differences in the rate of xylem production produce annual rings Summary of 1 o and 2 o growth in a woody stem If all cells of a body contain the same set of genes, how do they differentiate, and how does morphogenesis occur? For example, positional information determines whether the cells produced by an apical meristem become protoderm, ground meristem, or procambium If all cells of a body contain the same set of genes, how do they differentiate, and how does morphogenesis occur? Every step in development requires input from both genes and the environment!