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