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Plants (Ch
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(spore-bearing) nonvascular plants
a
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Ex: liverworts, hornwarts, mosses
2
...
Have vascular tissue but make spores instead of seeds
i
...
Seed (vascular) plants
a
...
Ex: cycads, ginkgo, other conifers (redwoods, junipers, yews), Gnetophytes,
Pines, Spruces, and Firs, angiosperms
The phylogeny of green plants

BIOL 197 Page 1

The life of plants
What must plants do to survive?
Feeding (autotrophic photosynthesis)
H20 + CO2 --(sunlight)--> O2 + sugars
Need sunlight, carbon dioxide, water
Need to live taller than competitors
Structural support
Reproduction
Need to disperse spores and gametes
Protect germinating plant
Life on land is difficult
What adaptations are required for terrestrialization?
1
...
Minimize loss of water
2
...
Acquire water from environment
3
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CO2 in; O2 out
4
...
Not too much (UV damage) or too little (shading)
5
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Gravity
6
...
Roots
7
...
Fertilization; protection of offspring

Adaptations for life on land
BIOL 197 Page 2

Adaptations for life on land
Solutions
Cuticle - waxy coating that protects plant from dehydration
Spores and pollen - coated (sporopollenin) to prevent dehydration, but require
water fertilization
Stomata - holes in cuticle that allow gas transport
Roots - water (and mineral fertilizer) uptake from soil
Also anchor the plant against wind, water, and gravity
Lignin (wood) - complex molecule provides structural support
Vascular tissue - transport water and minerals upward; transport products of
photosynthesis down
True vascular tissue is reinforced with lignin
Early Plants (Cooksonia)
The first plants had the basics needed to survive on land
Shallow root system allows water uptake and anchors plant
Photosynthetic stems conducted metabolism
Vascular-tissue-like-channels
Stomata like pores
Sporangia held spores above the soil (Sporangia is the organ that creates spores)
Cuticle and sporopollenin on body and spores above the soil
Xylem (wood)
Transport of water and soluble minerals from roots throughout plant
In trees, found primarily in the wood
Phloem
Transport of soluble organics (photosynthate) from leaves
Flows in different kinds of vascular cells
In trees, found just under the bark
Plants get taller
Initially, land plants were very short (~3 inches)
By 3800 million years ago, we begin to see trees
What happened?
1
...
Lignin
2
...
Accumulation of lignin-supported xylem tissue
3
...
Innovations to life cycle
a
...
Gametangia - specialized gamete-producing organs that protect gametes from
desiccation
1) Comparable to sporangia
2) Antheridium: sperm-producing gametangium (use mitosis to make
gametes, (testes use meiosis makes gametes))
3) Archegonium: egg-producing gametangium
BIOL 197 Page 3

3) Archegonium: egg-producing gametangium
ii
...
Reduction of gametophyte generations - unclear why occurred
1) Algae and early land plants dominated by gametophyte generation
2) Later plants dominated by sporophyte generation
a) Gametophyte in flowering plants only found in pollen and seeds
REVIEW MITOSIS/MEIOSIS DIAGRAMS BEFORE TEST
2
...
Outcrossing has benefits of sexual recombination
i
...
Dispersal allows greater outcrossing
i
...
Heterospory - production of different male and female spores
1) Pollen - male gametophyte, dispersed by wind or animals
2) Seeds - female gametophyte
a) Site of fertilization of gametes and nourishment of growing embryo
iii
...
Fruit - nutritional portion of flower surrounding seeds
Heterospory
1
...
Single type of spore develops into gametophyte that produces both sperm and eggs
i
...
All nonvascular plants and most seedless vascular plants
2
...
Microsporangia produce microspores that germinate into male gametophytes
(pollen) with antheridia that produce sperm
b
...
Brings small male structures long distance to large, nutritious and protective female
structure
i
...
Terrestrialization
2
...
Sepals
2
...
Stamen - Male organ
4
...
Wind
a
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Bees
a
...
Butterflies
a
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Birds (esp
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Red/Orange with long tubes, lots of nectar, little smell
5
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Nocturnal and white
Flowers encourage selective pollination
Fruits
Structure derived from flower ovary that encloses seeds
Improved seed dispersal
Nutrient used to reward animal dispersers
Biologist definition of a fruit:
Had to have been a flower at one point and have seeds in it
According to this, the following are fruits:
Tomatoes, acorns, peas, etc
...
) - sporangium
BIOL 197 Page 5

Sorus (sori, pl
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Seeds (female gametophyte)
2
...
Male and female cones
a
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Needle-like leaves
a
...
Reduced area for water loss
Boreal Pine Forests are the world's most important sink on land for carbon dioxide
Flowering Plants (Angiospermae)
Most diverse land plants today
>250,000 living species
Most are decidious
Diversity of leaf and plant morphologies
Worldwide distribution
BIOL 197 Page 6

Worldwide distribution
Tropic, grasslands, temperates, deserts, cold latitudes
Evolution linked to evolutionary diversification of insects
Oldest angiosperm is 125-m
...
-old Archaefructus
Ecologically (and agriculturally) important
Synapomorphies
1
...
Produce both pollen and seeds
(i) Seeds with carpel; pollen on stamen
(ii) Flowers can mature into fruit
2

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