Plant Tissue Systems Plant Structure and Growth Vascular Plant Body Shoot System – Root System –...
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Transcript of Plant Tissue Systems Plant Structure and Growth Vascular Plant Body Shoot System – Root System –...
Plant Tissue Systems
Plant Structure and GrowthVascular Plant Body Shoot System – Root System –Growth Determinate and Indeterminate Growth – Primary and Secondary Growth –
Classes of Flowering Plants Monocots and Eudicots Compared – Lifespans –
Plant Tissue Ground Tissue - Vascular Tissue - Dermal Tissue -
Primary Shoot Systems Features – Functions – Stems – Leaves –
Secondary Shoot Systems Growth –Woody Stem Structure –
Root Systems Features – Types of Roots – Zones of Primary Root Growth – Root Tissues –
Unit IIPlants
Learning Goal 2Describe the three main tissue
systems in the plant body.
Plant Structure and Growth
The Vascular Plant Body• Shoot system– Stems– Leaves– Flowers/Fruits
• Root system– Roots– Root Hairs– Root Cap
Growth
• Determinate growth common in animalsgrowth stops at a certain age
• Indeterminate growth – Plant grows throughout life– Meristems give rise to plant body– Increase in number of cells– Increase in size of cells
Primary Growth
• Apical meristems at root and shoot tips – Increases height of
shoot, length of roots
Secondary Growth
• Lateral meristems at root and shoot tips – Self-perpetuating cylinder of tissue– Increases diameter of stems and roots
Classes of Flowering PlantsEudicots and Monocots Compared
Lifespans
• Annual (one growing season)– Herbaceous
• Biennial (two growing seasons)– Roots, stems, and leaves first season– Flowers, fruits, and seeds second season
• Perennial (growth continues year after year)
Plant TissuesGround TissueParenchyma• Soft primary tissues– Thin primary cell
walls, pliable and permeable
– Specialized for storage, secretion, photosynthesis
CollenchymaFlexible support– Thicker primary cell
walls– Elongated cells in
strands or sheathlike cylinder
Sclerenchyma• Rigid support and
protection– Thick secondary cell
walls– Sclerids (protective
casings) and fibers (support)
Vascular Tissues• Xylem – Conducts water and dissolved minerals– Thick, lignified secondary walls– Dead when functional
• Tracheids– Elongated, tapered, overlapping ends– Lateral connections through pits
• Vessel members– Shorter, tubelike columns– Lateral connections through pits and perforations
Tracheids and Vessel Members
• Phloem– Conduct sugars and other solutes – Living when functional
• Sieve tube members– Joined end to end in sieve tubes– Sieve tube cells assisted by companion cells– End walls (sieve plates) studded with pores
Sieve Tube Members
Dermal Tissue
• Epidermis covers primary plant body – Waxy cuticle layer restricts water loss– Pairs of guard cells in leaf epidermis create
stomata (openings) for gas exchange
• Epidermal specializations– Trichomes (hairs) – Absorbent root hairs
Epidermal Tissue
Primary Shoot Systems• Features• Stems are adapted to provide support, routes
for vascular tissues, storage, and new growth
• Leaves carry out photosynthesis and gas exchange
• Plant shoots may have juvenile and adult forms
• Consists of main stem, leaves, and buds– Plus any attached flowers and fruits
• Functions:– Mechanical support– House vascular tissues– May store food and water– Buds and meristems for growth
Stems
• Organized into modular segments– Nodes: Where leaves and buds are attached– Internodes: Between nodes– Terminal bud: At apex of main shoot – Lateral buds: In leaf axils, produce branches
Stem Structure
Eudicot Vascular Bundles
• Form a stele (cylinder)– Outer cortex, inner pith
Monocot Vascular Bundles
• Scattered throughout ground tissue of stem
Modified Stems
Leaves
• Blade– Large surface area for photosynthesis and gas
exchange
• Petiole (in eudicots)– Attaches leaf to stem
Fig. 31.15, p. 725
b. Simple leaves (eudicot)
Poplar(Populus)
Oak(Quercus)
Maple(Acer)
Leaf Forms
Fig. 31.15, p. 725
Petiolule
c. Compound leaves (eudicot)
Red Buckeye(Aesculus)
Honey Locust(Gleditsia)
Black Locust(Robinia)
Leaflets
Leaf Adaptations
• Responses to environmental and herbivore pressures
Leaf Internal Structure
Secondary Shoot Systems
Growth• Vascular cambium gives rise to secondary
growth in stems
• Secondary growth can also occur in roots
• Secondary growth is an adaptive response
• Increases girth of roots and stems
• Vascular cambium– Produces secondary xylem and phloem
• Cork cambium– Produces cork, part of protective bark
Woody Stem Structure• Vascular cambium produces wood
• Cork cambium produces cork
• Bark– Living and nonliving tissue outside vascular cambium
(secondary phloem and periderm)
• Periderm – Cork, cork cambium, and secondary cortex
• Heartwood, sapwood
Root Systems
Features• Taproot and fibrous root systems are
specialized for particular functions
• Root structure is specialized for underground growth
• Absorb water and dissolved minerals
• Conduct water and minerals to aerial plant parts
• Anchor and support aboveground parts
• Often store food
Types of Roots
Zones of Primary Root Growth
• Zone of cell division– Root cap– Quiescent center
• Zone of elongation • Zone of maturation
Fig. 31.21, p. 730
Endodermis
a. Eudicot root
Root cortex
Pericycle
Primaryxylem
Primaryphloem
Stele(vascular cylinder)
Epidermis
Fig. 31.21, p. 730
Primaryphloem
b. Monocot root
Pith
Root cortex
Epidermis
Stele
Primaryxylem
Root Tissues
• Exodermis – Outer layer of root cortex
• Endodermis– Inner layer of root cortex
• Pericycle • Between stele and endodermis• Can function as meristem
LG 2 Vocabulary Terms
1. Apical/Lateral Meristems -2. Parenchyma -3. Collenchyma -4. Sclerenchyma -5. Cambium -6. Trachied -7. Nodes -8. Pith -9. Sieve Tube -10. Root Cortex -