Download Flowering Plants

Plant Kingdom
Ch. 27 & 28
Topics
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Common ancestor (green algal charophyte)
Adaptations to terrestrial life
Plant life cycles
Four major plant groups – cladograms
Ecology and economy
Plants
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Seedless Plants
Ch. 27. pp. 557-560.
~445 mya (Paleozoic era), plants colonized land
> 300,000 spp.
Across the Earth
Complex, mostly autotrophic, multicellular organisms,
small to huge (duckweeds to sequoias)
– Green algae (ancestors) and plants share
• Chlorophyll a and b, carotenoids
• Starch and cellulose
• Cell plate during cell division
• Alternation of generation
• Molecular homology
Major Adaptations
Seedless Plants
Ch. 27. pp. 558-560
More complex and variable alternation of generation
Gametophyte
Antheredia - sperms
Archegonia - an egg
Embryophytes
Sporophyte
Sporogenous
cells - spores
Plant Evolution
Seedless Plants
Ch. 27. pp. 558-561.
Issue of desiccation in dry atmosphere - cuticle and
stomata, embryo protected by archegonia, roots,
vascular tissue, lignin
Seedless Plants
Ch. 27. pp. 562-567.
Bryophytes - Nonvascular Plants
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Most closely related to green algal ancestor (charophyte)
Spores found in 460 million year-old sediments
>15,000 species
Typically small, require damp regions - no vascular
system, roots, stems, leaves
• Three groups:
– Liverworts (Phylum, Hepaticophyta - thalloid/leafy)
– Mosses (Phylum, Bryophyta - leafy)
– Hornworts (Phylum, Anthocerotophyta - thalloid)
Seedless Plants
Ch. 27. pp. 562-567.
Mosses: Phylum - Bryophyta. ~ 9,000 spp., importance of rain/standing
water to complete life cycle – many male-female separate
Seedless Vascular Plants
Club ‘mosses’ (Lycopodiophyta) and Ferns
(Pteridophyta) – two clades
• Vascular tissue - large size - strength - lignin
• Earliest vascular plants ~420 mya –
sporophytic dominance
Kingdom – Plantae
Ch. 27. p. 568-569.
Kingdom – Plantae
Ch. 27. p. 572-573.
Pteridophyta
Pteridophyta - Life Cycle
Kingdom – Plantae
Ch. 27. p. 573.
Seed Plants
Kingdom – Plantae
Ch. 28, p. 578-595.
Topics
• Seeds
• Gymnosperms: Naked Seeded Plants
– Cycads - Cycadophyta
– Ginkgo biloba - Ginkgophyta
– Conifers – Coniferophyta (Pinophyta)
– Gnetophytes - Gnetophyta
• Angiosperms: Flowering Plants – Anthophyta (Magnoliophyta)
– Flower – Two major classes
– Monocots – Class, Monocotyledones (Liliopsida)
– Dicots – Class, Eudicotyledones (Magnoliopsida)
• Adaptations of flowering plants
Kingdom – Plantae
Ch. 28, p. 578-580.
Seed
• Develops from
– Fertilized ovule
(Ovule = Megasporangium covered
by integument)
• Consists of
– Embryonic sporophyte
– Nutritive tissue
– Protective coat
Kingdom – Plantae
Ch. 28, p. 578-581.
Seeds - Reproductively Superior
• Development - more derived than spore
– Embryo is a tiny plant
– Spore is merely a haploid cell
• Contains food supply
– Allows development and growth until the new plant can
establish local nutritive support
• Covered by a tough seed coat
– Protection, extended dormant period
• Seeds covered in ovary (fruit) or not – Gymnosperms
and angiosperms
• Draw the cladogram of seed plants
Kingdom – Plantae
Ch. 28, p. 580-595.
Gymnosperms
Angiosperms
Seeds
Exposed on cone
Within fruit
Growth
Repr. structure
Woody tree/shrub
Cone (usually)
Woody/herbaceous
Flower
Pollen dispersal
Wind
Animals or wind
Fertilization
Egg + sperm
Egg + sperm
zygote
zygote
2 polar nuclei + sperm
Double fertilization in
endosperm
gnetophytes
Double fertilization
Fewer cell types
More cell types & more
efficient transport
Xylem & phloem
No. of species
Distribution
~840
Worldwide
>300,000
Worldwide
Kingdom – Plantae
Ch. 28, p. 580-584.
Gymnosperms – largest bodies
Cycadophyta
Dioecious
Ginkgophyta
• Only one species, G. biloba
native to China - dioecious
• Oldest genus of living trees;
200 million year old fossils look identical to modern
ginkgoes
• Pollution-tolerant, popular
urban tree
• Popular medicinal
Kingdom – Plantae
Ch. 28, p. 584-585.
Coniferophyta
Kingdom – Plantae
Ch. 28, p. 580-583.
• 630 species: pines, spruces, hemlocks, firs etc.
• Mainly monecious: male, female structures in same plant
– Strobili (cones) - reproductive structures
• Woody trees and shrubs - clear annual growth rings
• No herbaceous spp.
• Many conifers - make resin
– Sticky, protect plant from attack by insects and fungi
• Conifers - usually
evergreen, some deciduous
- bald cypress and
redwoods
Gnetophyta
Vessel elements, cone clusters
like flower clusters, and some
broad-leaved plants - like
Anthophytes – but likely not in
the same evolutionary lineage.
Kingdom – Plantae
Ch. 28, p. 580-585.
Kingdom – Plantae
Ch. 28, p. 585-595.
Flowering Plants - Anthophyta
– >300,000 species - dominant plants on Earth - economic
benefits
– From small herbaceous plants to huge trees
– Flowers - conspicuous or cryptic
– Sexual reproductive structure - flower - double fertilization
produces seeds within fruits
– Vessel elements in xylem; sieve tubes in phloem
(more efficient water/nutrient, and sugar conduction)
A complete flower
Kingdom – Plantae
Ch. 28, p. 586-587.
Feature
Eudicots
Monocots
Seed
Embryo with 2
cotyledons
Embryo with
1 cotyledon
Flower parts
Leaf venation
In fours/fives
Netted
In threes
Parallel
Vascular bundles in Arranged in
stem
ring
Scattered or
complex
Roots
Secondary growth
(wood, bark)
Fibrous roots
Absent
Taproot system
Often present
Kingdom – Plantae
Ch. 28, p. 586.
Kingdom – Plantae
Ch. 28, p. 589.
Kingdom – Plantae
Ch. 28, p. 590-591.
Adaptations of Flowering Plants
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Seed - protection + dispersal
Closed carpels (fruit) aid in dispersal (animal dispersal too)
Flowers attract pollinators
Pollen - well-adapted to cross-fertilization via pollinators
Double fertilization – increases reproductive success
Improved water and sugar transport in xylem and phloem
Broad leaves, well-developed roots - absorb and store nutrients
Cacti, Trees, Lilies, Vines, Shrubs - Sporophytic adaptations
critical to success