This document discusses the evolution of plants from single-celled organisms to complex multicellular plants over 450 million years. Key events included plants migrating from aquatic to terrestrial environments, developing vascular and root systems, evolving from spores to seeds, and more complex pollination methods. The stages of plant classification are also outlined, from algae to the divisions of flowering plants. The role of taxonomists in constructing dichotomous keys to identify organisms based on evolutionary relationships is also discussed.

1. Plant Evolution
by Annie Cloutier 2012
From a single cell to multi-cellular
Plants are the quiet autotrophs who
changed the planet
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2. Photons are particles of sunlight that autotrophs use to
create living plant cells
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4. Life and its journey through time
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5. Land plants evolved over a 450 million years time
I am an
aquatic plant
I am a
terrestrial
plant
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6. From the oceans and ponds migrating to land
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7. Stages of plant evolution include:
• From aquatic to terrestrial environments
• Developed of a vascular system (xylem and phloem)
• Developed a root system
• Evolved from spores to seeds
• Designed more complex pollination methods , many
with symbiosis
• Gametophytes to sporophyte
• Development of angiosperm (flowers)
• Naked seeds (gymnosperm) to enclosed seeds
(angiosperm)
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8. Algae > Green Red & Brown
evolved from cyanobacteria
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9. Kingdom Plantae
• Phylum Hepaticophyta (liverwort)
• Phylum Anthocerotophyta (hornwort)
• Phylum Bryophyta (mosses)
• Phylum Psilotophyta ( whisk fern)
• Phylum Lycophyta (club mosses)
• Phylum Polypodiophyta (conifers)
• Phylum Ginkgophyta (Ginkgo)
• Phylum Cycaophyta (Cycads)
• Phylum Gnetophyta (Gnetum, Epherdra,Welwitschia)
• Phylum Magnoliophyta (flower plants)
– Class Magnoliopsida ( dicots )
– Class Liliopsida ( monocots )
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10. How did scientist decide how to classify plants ?
• Plants are organisms with multi-cellular reproductive structures
• Some plants do not have true xylem or phloem
• Plants that have true xylem and phloem
• Plants with true leaves
• Plants with branching
• Plants with stems
• Plants with veins and silica
• Plants that reproduce by spores
• Plants reproduce by clones
• Plants reproduce by seeds
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11. What’s a taxonomist ?
• The cladogram chart shows the relationships between
organisms and their development and characteristics.
• It is also known as the “evolutionary trees” of living
organisms
• A taxonomist uses cladistics in the process of
establishing a relationship among organisms. Much of
the taxonomist work is inferred evolutionary
relationships
• So a taxonomist construct keys to aid in the
identification of organisms. Most keys are
dichotomous (branching lines), dealing in generalities
which can have occasional exceptions
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12. An example of a dichotomous key
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14. How does it work ?
Have you used a dichotomous key form ?
• Kingdom: Plantae
• Phylum: Magnoliophyta
• Class: Liliopsida
• Order: Liliales
• Family: Liliacae
• Genus:Allium
• Species: Allium cepra L.
• Common name “onion “
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15. Since Linnaeus’ time and early
botanical nomenclature…
• A number of classification categories have been added
between the levels of kingdom and genus.
• The Genera are now grouped into families
• Families into orders
• Orders into classes
• Classes into divisions (or phyla)
• And divisions into kingdoms
• Latin names are uses internationally so all scientist
learn the same vocabulary to identify plants
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16. Who tried to organize the plant world
first ?
• Greek Theophrastus 4th century B.C. he classified 500
plants !
• 13th century a distinction was made between
monocots and dicots
• 18th century European scholars began using Latin for
the first word genera groups (genus is single)
• Today Swedish naturalist Carolus Linnaeus’ 1707-
1778 designed a system of classification that is still used
around the world.
• He frequently lead field trips through the country-side
to identify plants accompanied musical band
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17. Learning can be fun !
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