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Faculty of Science, School of
Sciences, Lautoka Campus
BI509 Botany
Lecture 3: Importance of Plants II
What is botany?
Botany is the scientific study of plants.
Sometimes referred to as
plant science or plant
biology.
Looks at plants and their
place in the world.
But what is a “plant”?
It may seem like a silly question but it is hard to define the term “plant”
What do you
think is a
“plant”?
Is it something
with flowers?
Angiosperms
What do you think
is a “plant”?
Pseudotsuga
But what about
pine trees – they
don’t produce
flowers, are they
plants?
Gymnosperms
Podocarpus
Abies
Welwitschia
What do you think
is a “plant”?
mosses
club mosses
And those that
produce spores?
Are they plants?
“Bryophytes”,
ferns and fern
allies
ferns
Although these groups all have quite
different reproductive strategies most
people would accept they were “plants”
at least they are green!!
but in the past other groups have also
been included within the discipline of
botany or thought of as “plants”
Historically
“plant” and
botany has
also included
–
Fungi
Historically
“plant” and
botany has also
included –
Fungi
Lichens
Historically
“plant” and
botany has also
included –
kelp
Fungi
Lichens
Algae
Spirogyra
Historically
“plant” and
botany has also
included –
Fungi
Lichens
Algae
Bacteria
Traditionally botany has included
numerous very distinct groups
there have been several
characteristics regarded as
fundamentally “plant-like”, these
include –
being photosynthetic
having cell walls
being sessile
Traditionally researchers have
based their ideas about
relationships of organisms on
morphology.
In 1969, Whittaker’s five
kingdom system was based
on three basic forms of
nutrition (photosynthesis),
ingestion of food and
absorption of food in solution.
5 major lineages included fungi,
plants, animals, protists
(unicellular eukaryotes) and
monerans (prokayotes)
But the problem is these groups all have very different
features and may not have distinguishing
characteristics in common
Modern classification is based on molecular studies.
Scientist now have the ability to characterise and analyse DNA.
The molecular based tree is very
different from Whittaker (1969).
Instead of a single “Kingdom Monerans”
there are two prokaryote groups.
Organisms previously called “Kingdom Protists” do not form a
single group.
There are three domains not five kingdoms.
The Three Domain System
Prokaryote
Eukaryote
Classification of organisms in Six Kingdoms
Questions are
welcome