Kingdom Plantae Plant Morphology. Plant Evolution Ancestor = Charophytes member of the green algae.
Domain Eukarya Kingdom Plantae What makes a plant a plant? Cell wall primarily of cellulose Starch...
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Transcript of Domain Eukarya Kingdom Plantae What makes a plant a plant? Cell wall primarily of cellulose Starch...
Domain EukaryaKingdom Plantae
What makes a plant a plant?
• Cell wall primarily of cellulose
• Starch as primary photosynthetic storage product
• Multicellular with complex specialized tissue development
• Chl a, Chl b, xanthophylls, carotenoids
Plant evolution simplified
Radiates from simple to more complex – in both form and environments
• Seedless non-vascular
• Seedless vascular
• Seed producing, vascular
• Seed producing, vascular, fruits/flowers
Semi-aquatic to more terrestrial
• Ancestral “plants”
transitions to primitive plants– Requirements met from aquatic environment
• Gas, water, light, buoyancy support
• Complex plants– Adapt to two environments
• Shoot system
• Root system
Tracheophytes ancestral e.g. Rhyniophyta
• Ferns and “fern allies”
• Seedless
• Vascular plants– Xylem composed of
Tracheids – tapered porous cells
• capillary action moderately efficient
• Sporophyte dominant
Seed producing plants Gymnosperms
• Sporophyte dominant
• Conifers & relatives
• Heterosporous– Mega- and micro-
– Small gametophye matures in protected cones
• Female in ovulate cones• Male in staminate cones
– Wind blown-pollen
• Seeds protected in ovulate cone– Dispersed by wind, animal,
water sometimes
Angiosperms
• Sporophyte dominant
• Flowering plants
• Heterosporous– Mega- and micro-
– Small gametophye matures in protected flowers
• Female in flower ovary
• Male in flower anthers– Animal pollination and
some wind-blown
• Seeds protected in fruit– Dispersed by animal mostly
Seed? Ovule to seed• Ovule: sporophyte tissue surrounding sporangia
• Seed coat: protective diploid tissue
• Embryo: diploid zygote develops to sporophyte
• Endosperm: nutritive tissue surrounding embryo to feed it until it can photosynthesize on its own
Evolutionary importance of Seeds
• These plants produce pollen– Pollen produces sperm nuclei (no water requrd)
• Expand over drier habitats– Very protective over seasons (dormancy)
• Endosperm (embryonic food) – headstart
• Seed dispersal not dependent on water– Collected and distributed further
• Flowering plants…even further in fruits
Angiosperms /Anthophyta
• Flowering Plants (anth = flower)
• Seeds in a fruit (angio = container)
• Double fertilization (see life cycle)
• Like other pollen producers, is not dependent on water for fertilization
Plants:• Monecious
– Has both sexes
• Dioecious– Separate sexed plants
Flowers:• Perfect
• Imperfect
• Complete
• Incomplete
• Regular
• Irregular
• Inflorescences
Inflorescences
Vascular tissue
• Transport water, nutrients and food between roots and shoots
• System of xylem and phloem cells
• Varied organization in roots & shoots
Xylem cells – mature cells that become lignified (thickened 2o cellulose), dies, and perforates from lysosomes
• Tracheids– Primitive vascular plants
– Tapered, pits on ends, less capillary action vs. vessel elements
• Vessel elements– Less primitive vascular plants
– Pits on sides, open ends
– Stacked to form long tubes
– Advanced capillary action
• Transpiration– Roots → shoots → leaves → out– Via: root pressure and diffusion,
capillary pressure, negative pressure of evaporation and cohesion
Phloem cells – living cells that transport sugars (sap)
• Sieve tubes– no nucleus nor organelles– Open sieve plates
• Companion cells– Nucleated– Adjoined to sieve tubes via
plasmodesmata– Controls sieve tubes; regulates
movement• Translocation
– Movement of sugars; sources to sinks
leaves → roots, fruits, &/or meristems
Plant Structure• Apical meristem
– Mitotic division– Stem & root tips– Primary growth (length)
• Ground meristem– Mitotic division– Ground tissues:
• Parenchyma – large; storage• Collenchyma – smaller;
flexible support• Schlerenchyma – lignified;
rigid support; woody• Cambium
– Mitotic secondary growth– e.g. Vascular cambium– e.g. Cork cambium
Monocot root Dicot root
• Vascular bundles centered in roots
• Cortex = outer layer• Pith = center tissue• Stele = pith + vascular tissue
• Vascular bundles– Xylem, phloem, and
cambium in between
– Scattered throughout monocot stems
– Organized around periphery of dicots
• Cambium– Mitotic secondary
growth
– e.g. Vascular cambium
– e.g. Cork cambium
Monocot stem 2Sclerenchyma
Phloem
Sieve element
Companion cell
Xylem vessel
Air space
Inside
Outside
Fruit – ripened ovary that protects the seeds
• Ripened?• Layers of the ovary = Pericarp
– Exocarp• Outer layer /ovarian wall
– Mesocarp• Middle layer
– Endocarp• Inner/adjacent to ovules
Fleshy fruits
• One or more ovarian layer is fleshy– Drupe
• Endocarp is hardened; pit or stone• Peaches, nectarines, apricots, etc
– Berry• All or most pericarp is fleshy• Grape, tomato, etc
– Pepo• Berry with hard thick rind• Melons, pumpkins, etc
– Hesperidium• Berry with leathery rind• Citrus
– Pome• Swollen receptacle around ovary or
core• Apple, pear
Dry fruits
• Lacks fleshy tissue– Dehiscent fruits
• Split along a seam to disperse seeds
• Legumes – two seams• Capsules – multiple
seams• Bean, pea pods,
peanuts, etc
– Indehiscent• Do not split on a seam• Achenes, grains, nuts• Corn, wheat, etc
• Simple fruits– Single ovary of one
flower
• Aggregate fruits– Many ovaries of
one flower
• Multiple fruits– Many ovaries of
many clustered flowers (inflorescence)
• Accessory fruits– Tissue other than
ovary ripens (swollen)
What is a coconut? Fleshy? Dry? Other?
Drupe: a single fleshy fruit with a hard stone which contains the single seed
Plant Hormones (Ch. 39)
chemical communication and regulation
• Auxins– Cell elongation
– Apical dominance
– Abscission suppression• Slows the shedding of
leaves, flowers, fruits
– Fruit maturation
– Geotropism• Phototropism
• Gravitropism
A. The tips have been removed. No auxin is produced and the shoots do not grow longer.
B. The tips have been covered so light cannot reach them. Auxin is in the same concentration on both sides of the shoots, so they grow longer evenly on both sides.
C. One side of the tips are in more light than the other side. Auxin is in a greater concentration on the shaded side, causing the cells there to grow longer than the cells on the light side.
Plant Hormones (Ch. 39)
chemical communication and regulation
• Giberellins– GA or Giberellic acid
– Growth• Release some buds and
seeds from dormancy
• Dwarf plants lack GA– Spray on grapes =
bigger grapes
• Stem elongation– Spray on dwarf plants
= taller plants
• Related to flowering in some plants
Sold as common bio-fertilizer
Plant Hormones (Ch. 39)
chemical communication and regulation
• Cytokinins– Cell division
– Stimulate bud growth
– Stimulates fruit & embryo development
– Prevents leaf senescence
• Slows aging to decay With & without
Plant Hormones (Ch. 39)
chemical communication and regulation
• Abscisic Acid– General growth
inhibitor
– Induces dormancy• Wintering of buds
and leaves
– Closure of stomata
• Ethylene– Gaseous hormone
– Plays role in fruit ripening
– Fruit abscission• (shedding)
– One of the reasons why ripe bananas will “ripen” other fruits