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Plant Diversity lecture covering Mosses, Ferns, Gymnosperms and Angiosperms, based on Chapters 29 and 30 from Campbell & Reece "Biology" 8th edition (International). For ACS Biology 10, Sofia Bulgaria. March 2010
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Plant Diversity (Chapters 29 & 20)
All you ever wanted to know about plants…but were afraid to ask.
Jeff JewettAmerican College of Sofia
March 2010Version 1.0
Land Plants Happy 475,000,000 birthday!
• Land is great! – It’s so sunny!– Make me some sugar! (More CO2! More
nutrients)– No one is eating me (at first)
• Land is a bummer… – “This is heavy, man.”– “So…very…thirsty…”– “Pass the sunblock!”
Major groups of land plants
• Nonvascular– Bryophytes (Mosses, Liverworts, Hornworts)
• Vascular (93%)– Ferns– Seed Plants
• Gymnosperms (Conifers, Ginkos, Cycads)• Angiosperms (Flowering plants) (90%)
Moss –– the oldest land plant
• 120 families, 700 genera, 10,000 species• Non-vascular• Seedless, no flowers, non-woody (no lignin)• Require water for reproduction• Usually short (< 15 cm)• Usually found in moist environments
http://www.jnto.go.jp/eng/indepth/history/hj/moss.html
мъх
Gametophytes (haploid, 1N) are dominant part of life cycle
•Gametophyte (N) is dominant
(unlike vascular plants)
Sporophyte (2N) is short-lived parasite
http://www.botany.ubc.ca/bryophyte/stanleypark/basics.htm
Moss Sex?• Alternation of
generationsGametophytes (n)
gametes (n) zygote (2n) Sporophyte (2n) spore (n) back to gametophyte.
http://fashionindie.com/eating-disorder-campaigners-upset-with-kate-moss/
Moss Life Cycle Animation http://www.sumanasinc.com/webcontent/animations/content/moss.html
http://www.botany.ubc.ca/bryophyte/stanleypark/basics.htm
Ferns (Filicinophyta)
• 420 MYA• woody (lignified)
stems…can be tall!
• Vascular tissue• Roots & Leaves• Dominant form:
sporophyte (2N)
• seedless
ПАПРАТ
Vascular Tissue
• Xylem – moves water up from roots leaves
• Phloem – moves “phood” down from leaves to rest of plant
http://www.houghtonmifflinbooks.com/booksellers/press_release/studentscience/gif/xylem1.gif
Global Impact of Seedless Vascular Plants
(ferns and such)
• Vascular tissue & lignin allowed TALL plants
• Giant ferns during ~350MYA formed first forests
• Big increase in photosynthesis• CO2 in atm dropped 80%!!!• Global cooling, glaciers (brrr)• Irony: remains of these plants
became fossil fuels, burned today cause global warming. D’oh!
http://imagecache2.allposters.com/images/LPIPOD/BN9582_173-FB.jpg
www.morning-earth.org
Sori: where spores form
Fern Life Cycle http://media.pearsoncmg.com/bc/bc_campbell_biology_8/investigations/29A/index.html
Seed plants
• 300 MYA – swamps began to dry up, giving new “seed plants” advantage
• “Naked” (gymnosperms) and covered seeds (angiosperms)
• Seed: embryo with a food supply, in a protective coating
• Seeds are a detachable, mobile, womb (with embryo)
New & Improved!
• Shrunken gametophytes (microscopic)
• Male/female spores
• Ovules/pollen
Comparison of life cycles – learn this!
Pollen• Male gametophyte
surrounded by protective layer
• Sperm swimming through water (ferns & moss) can only go a few cm
• Pollen can go hundreds of KM by wind or animalhttp://www.zoology.ubc.ca/~bio336/Bio336/Lectures/Lecture5/pollen.jpg
Seeds vs Spores
SPORES (mosses & ferns)
SEEDS
2N 2N
Single-celled: embryo Multi-cellular: embryo plus food supply plus seed coat
No food supply Food supply – can lay dormant much longer
No protective coat Protective coat
Gymnosperms• ~305 MYA (150 MY before flowering ~305 MYA (150 MY before flowering
plants!)plants!)
• Some gymnosperms took advantage of Some gymnosperms took advantage of drier conditions with waxy cuticles and drier conditions with waxy cuticles and needle-like leavesneedle-like leaves
Gymnosperm Diversity
http://z.about.com/d/forestry/1/0/m/J/Gingko-Blaetter.jpg
Phylum GinkgophytaPhylum Ginkgophyta Phylum Phylum GnetophytaGnetophyta
Image: University of Wisconsin – Madison Botany
Phylum ConiferophytaPhylum ConiferophytaPhylum CycadophytaPhylum Cycadophyta
Image: University of Wisconsin – Madison Plant Systematics Collection
• Male pine cones (sporangia, pollen-producing)• Male & female pine cones
http://www.nps.gov/romo/male_pine_cones.htm
http://emhsbot-zoo.wikispaces.com/Plants
Angiosperms (Flowering Plants)• 250,000 species
(90% of all living plants!)
• Flower – specialized sex part
• Sepal, Petal, Stamen, Carpel
Fruit
• Protect dormant seeds
• Aid in dispersal
http://whatscookingamerica.net/Foto3/AvocadoPhoto.jpghttp://www.nwnature.net/plants/trees/images/P1060267.jpg
Monocot & (Eu)Dicot
• Cotyledon – seed leaf in the embryo
• Monocots = one seed leaf
• Dicots = two seed leaves
Mosses Ferns Gymnosperms Angiosperms
Dominant Life Form
Gametophyte Sporophyte Sporophyte Sporophyte
Vascular Tissue
No Yes Yes Yes
Woody Stem (with lignin)
No Yes Yes Yes
Seeds / Spores (2N)
Spore Spore Seed Seed
Male Gamete (1N)
Sperm (needs H2O)
Sperm (needs H2O)
Pollen Pollen
Flower / Fruit
No No No Yes