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Hello my name is Giles Johnson.
I'm a plant physiologist working at the University of Manchester in the UK.
This lecture today is going to introduce you to my subject,
and I've called it "Plant Physiology, A Primer".
So when talking about plants,
the first thing we really need to consider is what is a plant?
If I asked you that question probably,
an image will come in your mind it will look something like this.
So it will be a green thing.
It'll have leaves which are flat green structures.
It may have flowers, and if you pull it out of the ground,
it will have a rigged system.
But when we talking scientifically about plants,
we need to go into a little bit more detail and really know what we're talking about.
So at that point, I commonly turn to a dictionary for a formal definition.
So this I've taken from the Oxford English dictionary.
So here they have a definition of a plant "as
being a living organism other than an animal,
which is able to subsist wholly on inorganic substances."
This is a very important feature about plants.
Is not true of all plants,
but it is a general trend in the plant kingdom.
Typically, a plant will be fixed to a substrate.
We say that plants don't move around very much.
Again, there are some exceptions.
But generally speaking, plants don't walk around.
They have the characteristic of having cells which is surrounded by cellulose cell wall.
Finally, the majority of plants survive by carrying out a process called photosynthesis.
So we can summarize that in two words.
Firstly, we say plants are autotrophic,
that means they live on inorganic substances, and specifically,
that they are photoautotrophic,
they live on light as their source of energy,
and we say that they are sessile,
they do not move around.
These two characteristics are important in defining what a plant is.