Kingdom PlantaeExtended

Divisions

The plant Kingdom is divided into Divisions rather than Phyla

We only need to know about:

The Ferns and

Angiosperms (flowering plants)

Mosses (for interest only)

Mosses are small plants that only grow in damp areas because they do not have a cuticle to stop them drying out

They so not have proper leaves, stems or roots

Ferns (Pteridophytes)–

you need to know about these

These plants dominated the world when dinosaurs were around but are not so common now

They have a cuticle so can grow in dryer areas

They have true roots and stems with xylem and phloem to transport water and sugars

They spread using rhizomes that grow away from the parent plant

The leaves are called frondsThese grow by unfurling from fiddleheads

Fern life cycle - there are 2 stages

The plant we see is the sporophyte

These have a full set of chromosomes in their cells

We call this 2n chromosomes

On the back of the fronds we find sori

Spores are made in these by cell division called meiosis

This gives the spores half the number of chromosomes or n

Spores are released and blown by the wind

When they land in soil they can grow into a tiny microscopic pant called a prothallus

This has only half a set of chromosomes

The prothallus is also called a gemetophyte because it makes gametes (sex cells)

These are made by mitosis so they have half a set of chromosomes

These are like roots

This is a leaf-like structure but is very small

The male and female sex cells fuse to form a new plant with a full set of chromosomes

It grows out of the gametophyte

And becomes an adult sporophyte

Because they are pretty ferns are popular house and garden plants

Gymnosperms (for interest only)

These are plants that reproduce using cones – like Pine Trees

The forests in North America and Europe are mostly coniferous

They have “soft wood” and grow quickly so are grown for paper and furniture

Angiosperms – flowering

Plantsyou need to know this group

Most of the plants we see are angiosperms

They reproduce using flowers (sometimes the flowers are so small we can’t see them)

The plants may be trees, shrubs, grasses, or herbs

All of our important crops are angiosperms

There are two main groups:

Monocotyledons and Dicotyledons

The names of theses groups comes form the number of cotyledons in the seeds

The Cotyledon is a food storage area: Dicotyledons have 2 and Monocotyledons have one

Use this information to start filling in the table on

In fact these days scientists divide the groups by what the pollen looks like

Monocotyledons have one furrow, Dicotyledons have two or more

These pollen grains have been highly magnified by a scanning electron microscope

RootsMonocotyledon roots are fibrous – they branch out just below the soil

This makes plants like grasses useful for holding soil in place and preventing erosion

Dicotyledons tend to have tap roots – this is a long main root with side (lateral) roots coming off it

Dicotyledon roots can go deep into the soil to find water

The next slide has some simple drawings for you to copy

If we look at the roots in cross section we will see:

Monocotyledons have a ring of xylem and phloem and a central pith – this is packing cells or a hollow region

Dicotyledons have the xylem and phloem in the middle

We will learn how xylem carries water and phloem carries sugar later this year

Monocotyledon root T/S

Dicotyledon root T/S

Epidermis

Xylem and Phloem

Pith

Epidermis

Cortex

Xylem and Phloem

Stems

Vascular bundles

monocot

Dicot

Xylem and phloem are grouped together in stems to form vascular bundles

In Monocotyledons the vascular bundles are scattered around

In Dicotyledons they are neatly set in a ring near the edge

Monocotyledon Stem

Dicotyledon Stem

Epidermis

Vascular bundles

Epidermis

Vascular bundles

leaves

monocotyledon

dicotyledon

petiole

One of the easiest ways to tell Monocotyledons from Dicotyledons is by the veins in their leaves. Veins are made of the xylem and phloem

In Monocotyledons the veins are parallel and there is no petiole (stem)

In Dicotyledons the veins are net-like and they have a petiole

Can you work out the magnification of these leaves using the scale bar?

Flowers

We will learn about flowers next year

For now be aware that the flower parts (petals, anthers) come in 3’s in Monocotyledons, and in 4’s or usually 5’s in Dicotyledons

Most monocotyledons are grasses and are wind pollinated so the flowers are really small and not brightly coloured

Check you have filled in the table completely in your notes