Download Plant History

10/1/2012
BI 103: Plants
Plant Family History
Taxon: A Ranked Hierarchy
Kingdom: Plantae
Phylum: Magnoliophyta
Class: Magnoliopsida
Order: Rosales
Family: Rosaceae
Genus: Malus
Species: Malus pumila
Adaptation to Land
For a Plant: What are the differences between life
on land and life in the water?
 Variation in temperature - fluctuation, not
buffered by water
 Variation in moisture - no longer continuously
bathed in water
 Nutrient availability - differences between water
and soil and how nutrient uptake occurs
 Gravitational force - floating at the surface was
sufficient to get to the sun
 Substrate - differences between water and soil
Adaptation to Land
What types of adaptations are needed to
move from water to land habitat?
Protection against water loss
Cuticle to prevent water loss, stomata for regulation
Ability to tolerate variation in temperatures
Roots for anchoring to substrate and nutrient
absorption
Protection for gametes: specialized structures
Gametes (sperm) do not require water
Development of vascular tissue
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Bryophytes
• Gametophyte generation dominant
• true organs lacking
• thallus (undifferentiated plant body)
• rhizoids (root hair like structures)
•unicellular or multicellular; anchorage
function only
•Pores: allow gas exchange; don’t close
• conducting tissues absent or primitive
• water required for fertilization
Bryophytes: non vascular
plants: Liverworts
Gemmae cups
Create liverwort Clones!
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Liverwort
Bryophytes: Non vascular
plants: Moss
Bryophytes: Non-vascular plants:
Moss
Hornworts!
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Vascular plants: Derived
adaptations
Vascular tissue: conducts water
and nutrients throughout the plant
Plant organs: roots, stems, leaves
Sporophyte generation dominate
(plant spends more of its life in the
sporophyte (2n) generation
Lycophytes: “club mosses”
Sporophyte dominate
generation
Vascular tissue
Stems, roots, leaves!
Strobilus: where spores
are produced via meiosis
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Pterophytes (ferns and allies)
• 11,000 extant species, mostly in
the tropics; many extinct
• Psilotales: whisk ferns(no roots)
• Equisetales: horsetails
• roots, stems & leaves present
• sporangia variable in Sori, not
strobilus
TRENDS THROUGH TIME
Pterophyte:Fern Life cycle
Ancestral
Derived
Mosses & Liverworts
Club mosses,horsetails, Plants we’ll cover next
week…
whisk ferns & ferns
Non-vascular
Spores
Gametophyte-dominant
Sperm require water
Vascular
Spores
Sporophyte-dominant
Sperm require water
Vascular
Seeds!
Sporophyte-dominant
Sperm don’t need water
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10/1/2012
Moss
Motile sperm
Gametophyte-dominant
 Cuticle
 Homospory


Gametophyte
-dominant
Liverworts
Gammae cups
Motile sperm
 Gametophyte-dominant
 Cuticle
 Gemmae cups
 Homospory

Chlorophyta
Green algae
Ex: Chara
Motile sperm
Cuticle
Strobili
Gymnosperms
Pterophytes
Lycophyta
Vascular tissue
Motile sperm
 Sporophyte-dominant
 Cuticle
 Heterospory
 Roots and leaves
 Strobili

Sori
Pterophyta
Vascular tissue
Motile sperm
Sporophyte-dominant
 Cuticle
 Heterospory
 Roots and leaves
 Sori

Seeds
Lycophytes

Vascular tissue
Sporophyte-dominant
Roots and leaves
Angiosperms
Bryophytes
Vascular tissue
Green algae:
Chlorophytes
Land plants


Gymnosperms
Coniferophyta
(pines and cone
bearing trees)
Cycads (palmlike)
Ginkgos (ginkgo
trees)
Gnetophyta
(gnetums)
Gymnosperms: Ginkgo
Long thought to be
extinct in western
civilization, until
travelers from
Germany found it
while visiting temples
in China and Japan.
Flagellated sperm
Dioecious (separate
male and female
plants)
Fleshy outer covering
to seed (not true fruit)
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Gymnosperms: Cycadophyta
Flagellated sperm
still, but use of
pollen tube
Palm-like plants,
but have cones for
reproduction
Endangered by
poaching and a
black market
Gymnosperms: Gnetophyta
Ephedra
Temperate regions
except Australia
Welwitchsia
Namibia
Gnetophyta: Welwitchsia
Gnetum
Old and New
World Tropics
• Flower-like structures
• Vessels in xylem== not found in other Gymnosperms
• double fertilization
• Also loss of flagellated sperm and uses pollen tube.
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10/1/2012
Gnetophyta: Ephedra in Utah
Gnetophyta:
Ephedra spp.== Mormon tea
oNaked seeds
oUse of pollen tube
oThick cuticles
oPhotosynthetic stems in
Ephedra
Gymnosperms: Coniferophyta
 Key characteristics:
 Loss of flagella on sperm, sperm conducted to
egg by a pollen tube.
 Needle-like or scale like leaves
 Thick cuticle
 Recessed stomata
 Resin
 Cones
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What are the advantages of
flowering?
Discuss the question in groups of 2-3
students
5 min
Angiosperms: the Flowering
plants
What are the advantages to the plant?
Less inbreeding
Higher probability the pollen will reach
the right plant
They don’t have to produce as much
pollen
Enlists partnerships with insects and
other animals
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