Anatomy, Morphology, & Growth of Angiosperms – Ch. 5-8
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Transcript of Anatomy, Morphology, & Growth of Angiosperms – Ch. 5-8
Anatomy, Morphology, & Growth Anatomy, Morphology, & Growth of Angiosperms – Ch. 5-8of Angiosperms – Ch. 5-8
Two plant groups: monocots & dicots
Structure Reflects Function
http://www.fugu-sg.org/~elia/cambodia/templesfacesweb/pages/A3_Embracing_Roots.htm
Structure of a plant determined by:
1. Genetics2. Environment – two time scales:
1. Long-term:
2. Short-term: plasticity = wide range of phenotypes for each genotype. Allows plants to adjust to changing environment (ex. Shorter plant in dry year so that it can still reproduce)
Cells
Tissues
Organs
Systems
Muscle cell
Muscle tissue
Heart
Circulatory system
Three organs: Roots, stems, leaves
1. Roots–
• Store food (carbos from photosynthesis) to be used for flowering & fruiting
• Covered with root hairs – increased surface area for absorption
Fig 35.2
Modified Roots – Fig
35.4
Prop roots
Sweet Potato – storage root
Aerial strangler roots
Buttress roots
Pneumatophores
2. Stems/shoots
• Support, transport• Some photosynthesis• Two types of shoots
1. Vegetative –
2. Reproductive – • Two parts of stem:
1. Node –
2. Internode – stem segments between nodes
Two types of buds
1. Terminal bud – contains a shoot apical meristem; shoot growth is concentrated here
2. Axillary buds –
Apical dominance = the presence of an apical bud inhibits the growth of axillary buds.
-remove or depress apical bud, axillary buds begin to grow.
Modified Shoots (stems):
• Stolons –
• Rhizomes –
• Bulbs – swollen underground shoots
• Tubers – swollen rhizomes
Asexual, vegetative propagation
Stores food for later growth
Fig 35.5
3. Leaves – main photosynthesis organs
http://www.knotweed.co.uk/japknot_Info.htm
Modified leaves
• Compound, doubly compound – why??
Fig 35.7 – Modified leaves
Tendrils
Spines
Succulents
Leaf types:
Simple leaf =
Compound leaf = divided into distinct units called leaflets
Four types of leaf arrangement:
1. Acaulescent –
2. Alternate –
3. Opposite – leaves borne across from each other at the same node
4. Whorled – 3 or more leaves arising from the same node.
Three main tissues: Dermal,
Vascular, Ground
Fig 35.8
1. Dermal tissue or epidermis
• Root hairs are specialized epidermal extensions• Secretes waxy cuticle of the leaf
2. Ground Tissue
• fills the space between dermal and vascular tissue systems.
• Diverse functions:
pith
cortexIn dicots:
3. Vascular Tissue
• function in transport between roots & shoots, and structural support of plant– Xylem:
– Phloem: Food transported to roots & non-photosynthetic parts such as the flowers
The Plant Cell
Fig 7.8
5 Differentiated Plant Cell Categories
1. Parenchyma
2. Collenchyma
3. Schlerenchyma
4. Water-conducting cells of the xylem
5. Sugar-conducting cells of the phloem
1. Parenchyma
• thin and flexible cell walls
2. Collenchyma
• Usually grouped in strands to support young parts of plants without restraining growth
• Flexible, elongate with growing shoots
3. Schlerenchyma
• May be dead at functional maturity – ???
• cell walls left behind as skeleton
4. Water conducting cells of the xylem:
• 2 types: tracheids & vessel elements
Tracheids
• Water flows from cell to cell (laterally) through pits in cell wall
• Support function
Vessel Elements
• End walls are perforated for free flow of water• More efficient as water conductors than tracheids
Fig 35.9
5. Sugar-conducting cells of the phloem
Sieve-tube members:
• Lack a nucleus, ribosomes, vacuole• Cells separated by perforated sieve plates –
allow sugar movement
Fig 35.9
Growth & Development
http://www.cneccc.edu.hk/subjects/bio/album/Chapter20/PLANT_GROWTH.html
• Development =
Three processes of development:
1. Growth =
2. Cellular differentiation = generation of different cell types
3. Morphogenesis – creation of body form & organization.
1. Growth
• Cell division no expansion
• = due to water uptake in the vacuole
Growth
Fig 35.24
Cell division
• Occurs in only in meristems!
Meristems
• =
• Two types of meristems:1. Apical meristem –
2. Lateral meristems – extend lengthwise along the axis of the stem & roots. Responsible for growth in girth in older parts of the plant (called secondary growth). Exist only in perennials
Fig 35.10
Primary Growth of Roots
• Root cap – layer of cells that protect the RAM as it pushes through the soil
Fig 35.12
Arrangement of Primary Tissues in Roots
1. Epidermis –
2. Stele –
3. Ground tissue – mostly parenchyma cells of the cortex – area between the stele & epidermis; stores food & takes up minerals.
• Endodermis – single cell layer between cortex & stele. Selective barrier for uptake of soil solution contents into vascular system.
Fig 35.13
Epidermis
Cortex
Endodermis
Stelexylem
phloem
Eudicot/Gymnosperm root cross section
Primary Growth of Shoots
• Bud = cluster of leaf primordia created by meristem. No internodes
• Lateral branches arise from axillary buds
Fig 35.15
Primary tissue arrangement of stems
– Ground tissue = pith & cortex
Fig 35.16
pith
cortex
epidermis
phloem
xylem
Schlerenchyma cells
Eudicot/Gymnosperm stem cross section
Tissue arrangement of leaves
• 3 parts:
1. Upper & lower epidermis – tightly interlocked cells, secrete waxy cuticle. Contains stomata flanked by guard cells
2. Vascular tissue –
3. Mesophyll – ground tissue between upper & lower epidermis
Fig 35.17
Secondary Growth
• Two lateral meristems:
1. Vascular cambium – produces secondary xylem (= wood) & phloem
2. Cork cambium – replaces the epidermis with cork: tough, thick cover for stems, roots.
Secondary growth of stems
• Vascular cambium – layer of cells between primary xylem & primary phloem. Puts on successive layers of secondary phloem to outside & secondary xylem to inside =====> stem widens
• Wood = accumulation of secondary xylem. Dead at maturity, contains lignin
Cork cambium
• “bark” =
• Cork continually sloughs off
Fig 35.18
Fig 35.20
Three types of life cycles:
1. Annual –
2. Biennial – complete life cycle in two years (first year = vegetative, second year = reproductive). Some need a cold winter period to initiate flowering from vegetative state. Ex. carrots
3. Perennial – live year after year, do not die after reproduction. Examples: trees, shrubs, some grasses. Causes of death = fire, disease