Plant Diversity II: The Evolution of Seed Plants Chapter 30.
Plant Diversity II: The Evolution of Seed Plants (Ch.30)
-
Upload
joseph-russell -
Category
Documents
-
view
267 -
download
0
Transcript of Plant Diversity II: The Evolution of Seed Plants (Ch.30)
![Page 1: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/1.jpg)
Plant Diversity
II: The
Evolution of Seed Plants (Ch.30)
![Page 2: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/2.jpg)
Transforming the World
Seed replaced the spore• Zygote develops into embryos with a food supply in a
protective seed coatPollen is vehicle for sperm cells• Coated with sporopolleninReduction of the gametophyteHuge impact on human societyFive Derived Traits of Seed Plants1. Reduced gametophyte2. Heterospory3. Ovules4. Pollen5. Seeds
![Page 3: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/3.jpg)
Transforming the World
![Page 4: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/4.jpg)
Advantages of Reduced Gametophytes
Tiny gametophytes can develop spores retained within the sporangia of the parental sporophyte• Protected
during environmental stress
• Obtain nutrients from sporophyte
![Page 5: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/5.jpg)
HeterosporyAll are heterosporous• Megasporangia (female
gametophyte)• Microsporangia (male gametophyte)
Figure 30.3a
(a) Unfertilized ovule. In this sectional view through the ovule of a pine (a gymnosperm), a fleshy megasporangium is surrounded by a protective layer of tissue called an integument. (Angiosperms have two integuments.)
Integument
Spore wall
Megasporangium(2n)
Megaspore (n)
![Page 6: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/6.jpg)
Ovule and Production of Eggs
Megasporangium is within the parent sporophyteInteguments• Layer of sporophyte tissue that envelops and
protects the megasporangium• Gymnosperms have one; angiosperms have twoOvule• Megaspore, megasporangium, and
integuments
![Page 7: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/7.jpg)
Pollen and Production of Sperm
Pollen grain• Develops from a microspore• Male gametophyte enclosed
within the pollen wall• Outer wall contains sporopollenin• Can be carried long distances by
wind and animalsPollination• Transfer of pollen to the part of
the seed plant that houses the ovule
![Page 8: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/8.jpg)
Gymnosperms
![Page 9: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/9.jpg)
Gymnosperm Evolution
• “Naked seeds”• Lack ovaries• Water transported by
tracheid cells• Conifers
– Cone bearing gymnosperms– Spruce, pine, fir, redwood
![Page 10: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/10.jpg)
Gymnosperms• Division
Coniferophyta (conifers)
• Division Cycadophyta (Cycads)
• Division Ginkgophyta (Ginkgo)
• Division Gnetophyta (Welwitschia)
![Page 11: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/11.jpg)
GinkgophytaGinkgo bilobaTolerates air pollution wellOrnamental• Usually only plant males b/c seeds
smell rancid
![Page 12: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/12.jpg)
• Cycads• Second largest
group• Large cones• Palmlike
leaves• Thrived during
age of the dinosaurs
Cycadophyta
![Page 13: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/13.jpg)
• Tropical or deserts• Diverse but shared
molecular data• 3 genera
– Welwitschia (deserts of southwestern Africa)
– Ephreda (produces ephedrine used as a decongestant)
– Gnetum (tropical trees, shrubs, vines native to Africa and Asia)
Gnetophyta
![Page 14: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/14.jpg)
ConiferophytaLargest of the 4 divisions Cone• Reproductive structureMost are large treesMost are evergreensNeedles• adaptation for dry climates• Reduces # of stomata and have a thick
cuticle
![Page 15: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/15.jpg)
• The conifers, phylum Coniferophyta, is the largest gymnosperm phylum.
– Although there are only about 550 species of conifers, a few species dominate vast forested regions in the Northern Hemisphere where the growing season is short.
– The term conifer comes from the reproductive structure, the cone, which is a cluster of scalelike sporophylls.
![Page 16: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/16.jpg)
• Much of our lumber and paper comes from the wood (actually xylem tissue) of conifers.
– One bristlecone pine, also from California, is more than 4,600 years old.
– Redwoods from northern California can grow to heights of over 100m.
• Coniferous trees are amongst the largest and oldest organisms of Earth.
– This tissue gives the tree structural support.
![Page 17: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/17.jpg)
Conifers include pines, firs, spruces, larches, yews, junipers, cedars, cypresses, and redwoods.
![Page 18: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/18.jpg)
Life Cycle of a Pine1. Most conifers have both ovulate and pollen cones2. Haploid microscores produced by meiosis which
develops into a pollen grain3. Ovulate cone has two ovules, each containing a
megasporangium4. Pollination occurs; pollen tube germinates that digests
the megasporangium5. Megasporocyte undergoes meiosis producing 4
haploid cells, one survives as a megaspore6. Megaspore develops into female gametophyte that
contains 2-3 archegonia, each will form an egg7. Egg matures and 2 sperm cells have formed in the
pollen tube8. Fertilization occurs (usually a year after pollination)
– One zygote becomes the embryo; ovule becomes the seed
![Page 19: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/19.jpg)
Life Cycle of a Pine
![Page 20: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/20.jpg)
Angiosperms
![Page 21: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/21.jpg)
Angiosperms• Division
Anthophyta• Flowering plants• Most diverse and
geographically widespread
• Split into monocots and dicots
• Xylem is more specialized for water transport– Vessel elements
![Page 22: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/22.jpg)
Characteristics of Angiosperms
Flowers• Specialized structure for sexual reproductionCompressed shoot with 4 whorls of modified
leaves• Sepals (nonessential)• Petals (nonessential)• Stamens (essential)• Carpels (essential)
![Page 23: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/23.jpg)
FlowerSepals• Protect and enclose budPetals• Used to attract pollinators and
enclose reproductive structuresCarpels• Female reproductive structures• Pistil – fused carpelsStamens• Male reproductive structures
![Page 24: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/24.jpg)
StamenEssential
flower partFilament• Supports the
antherAnther• Produces the
pollen
![Page 25: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/25.jpg)
Carpel
Essential flower partStigma• Sticky to trap the
pollenStyle• Leads to the ovary
from the stigmaOvary• Produces the
ovules
![Page 26: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/26.jpg)
Figure 30.13a The structure of a flower
![Page 27: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/27.jpg)
Figure 30.13a The structure of a flower
![Page 28: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/28.jpg)
Characteristics of Angiosperms
Fruits• Mature ovary• Protects dormant
seeds• Aid in the dispersal of
seeds• Fleshy or dry• Propellers, burrs,
edible
![Page 29: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/29.jpg)
FruitsFruits• Typically consist of a mature ovary
(b) Ruby grapefruit, a fleshy fruitwith a hard outer layer andsoft inner layer of pericarp
(a) Tomato, a fleshy fruit withsoft outer and inner layersof pericarp
(c) Nectarine, a fleshyfruit with a soft outerlayer and hard innerlayer (pit) of pericarp
(e) Walnut, a dry fruit that remains closed at maturity
(d) Milkweed, a dry fruit thatsplits open at maturity
![Page 30: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/30.jpg)
FruitsSimple fruit•Single ovary of
one flower
![Page 31: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/31.jpg)
FruitsAggregate fruit•Several ovaries are part of the
same flower (raspberry)
![Page 32: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/32.jpg)
FruitsMultiple fruit•Develops from several separate
flowers (pineapple)
![Page 33: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/33.jpg)
Angiosperm Life Cycle1. Microsporocytes on anther divide by meiosis producing
microspores2. Microscpore develops into a pollen grain; generative cell
divides 2 sperm; tube cell produces pollen tube3. Megasporocytes divides by meiosis producing 4 megaspores;
one survives forming the female gametophyte4. After pollination, 2 sperm cells are discharged
• Pollen tubes absorbs water and germinates; penetrates through the micropyle
5. Double fertilization occurs• One sperm fertilizes the egg zygote with rudimentary root and
cotyledons• One sperm fertilized the central cell endosperm (3N; food source)
6. Zygote develops into the embryo and is packaged in a seed7. Seed germinates developing into a mature sporophyte
![Page 34: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/34.jpg)
![Page 35: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/35.jpg)
Angiosperm Life Cycle
![Page 36: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/36.jpg)
Angiosperm Diversity
Monocots
Dicots• Now called Eudicots
Basal AngiospermsMagnolids
![Page 37: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/37.jpg)
Monocots vs. Dicots
![Page 38: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/38.jpg)
Evolutionary Links Between Angiosperms and Animals
• Pollination of flowers by animals and transport of seeds by animals– Are two important relationships in terrestrial
ecosystems
(a) A flower pollinated by honeybees. This honeybee is harvesting pollen and nectar (a sugary solution secreted by flower glands) from a Scottish broom flower. The flower has a tripping mechanism that arches the stamens over the beeand dusts it with pollen, some ofwhich will rub off onto the stigmaof the next flower the bee visits.
(c) A flower pollinated by nocturnal animals. Some angiosperms, such as this cactus, depend mainly on nocturnal pollinators, including bats. Common adaptations of such plants include large, light-colored, highly fragrant flowers that nighttime pollinators can locate.
(b) A flower pollinated by hummingbirds.The long, thin beak and tongue of this rufous hummingbird enable the animal to probe flowers that secrete nectar deep within floral tubes. Before the hummer leaves, anthers will dust its beak and head feathers with pollen. Many flowers that are pollinated by birds are red or pink, colors to which bird eyes are especially sensitive.
![Page 39: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/39.jpg)
Global Impact• Agriculture is based almost entirely
on angiosperms– Provide nearly all of our food
• Provide a nutritional foundation for terrestrial ecosystems
• Contributed to the cooling of the Earth and maintaining temps. by lowering CO2 levels
![Page 40: Plant Diversity II: The Evolution of Seed Plants (Ch.30)](https://reader035.fdocuments.in/reader035/viewer/2022081416/56649e625503460f94b5dcf6/html5/thumbnails/40.jpg)
Products from Seed PlantsHumans depend on
seed plants for• Food• Wood• Many medicines