Introduction:

All modern terrestrial plants are the descendants of algae (a protist) that adapted to a terrestrial habitat

roughly 500 million years ago. Compared to water, land is an erratic habitat where temperature and moisture

availability may change abruptly and dramatically.

What were the adaptations that these primitive plants needed to survive on land?

A) Surrounded by air, the land plan is in constant threat of dehydration and must have wa-

terproofing, usually in the form of a waxy cuticle layer.

B) While algae could obtain nutrients from the surrounding water, land plants needed to ex-

tract minerals (and no, even water!) from the soil; roots adapted to take on this task.

C) Evolution of rigid structural support allowed plants to grow to new heights, and better compete for

sunlight.

D) Height must have coevolved with vascular (transport) tissue, the internal plumbing system needed to

transport water and nutrients from the roots, skyward.

E) Reproduction now became problematic as well, as sperm could no longer swim

through open water to a joyous meeting with the egg. Thus, evolved sperm cells protected with-

in pollen grains that could instead use wind, and later, unwitting animals to be carried to the

egg. Finally, ,the seed evolved to better protect the next generation until favourably conditions

(or the correct season) arrived.

Plant Diversity Lab and Notes: Station 1

The Major Phylum of plants and how they evolved

There are 4 major groups that evolved in the

following sequence

1. Bryophytes: which include mosses

2. Seedless vascular plants: which include the

ferns

3.Gymnosperms: many of which are also

called conifers.

4. Angiosperms: the ‘flowering’ plants, which

now dominate

Where did they come from?

Ancestral algae began to invade the land early in the Paleozoic era, and plants that closely resemble modern

Bryophytes appeared shortly (say… 100 million years!) thereafter.

Plant Diversity Lab and Notes: Station 2

What are the sporophyte and gametophyte?

In animals, the adult (male or female) has specialized

organs that produce reproductive cells called gametes

(sperm or egg cells). Upon fertilization, the egg and

sperm combine to produce a zygote that can grow into

another male or female adult.

Unlike ANIMALS, plants have two alternating life

stages. The figure shows the ‘altering of genera-

tions’ as it occurs in a fern.

1. One stage– the sporophyte– produces spores.

2. The spores develop into a gametophyte stage

plant, which may be male or female.

3. Gametophytes produce EITHER sperm or egg

gametes.

4. Egg and Sperm cells unite and grow into another

sporophyte.

Notice: Spores develop into a whole plant; gametes must first unite then develop. ANIMALS DO NOT

PRODUCE SPORES.

Plant Diversity Lab and Notes: Station 3

These are considered to be the most primitive of the plants. They are typically only found where water is

readily available, and never grow more than a few inches tall for lack of a vascular system.

Characteristics of Bryophytes:

Disperse through spores, not seeds

Lack Vascular Tissue

Gametophyte stage is dominate. Bryophytes are the ONLY

group of plants where the gametophyte stage is larger than the

sporophyte stage.

Plant Diversity Lab and Notes: Station 4

Note: Not everything called a

‘moss’ is a bryophyte. For exam-

ple; Spanish moss is a flowering

plant.

Plant Diversity Lab and Notes: Station 5

In swamps, bogs, rainforests, well adapted to nutrient poor soils

Tolerant to cold temperatures - most abundant plants in polar regions

Spagnum mosses have sponge-like properties and form thick deposits of peat which can be burned as a fuel or used in gardening.

Peat Moss

Factoid- Bodies have been preserved in a mummified state, in peat bogs. This one was found in Ireland in 2003. He was probably hung as a sacrifice.

Everything has been preserved including hair, clothing and the rope they used to kill him.

Seedless Vascular Plants

The Vascular Plants are believed to have evolved from moss-like plants

300-400 million years ago. They were the first plants to grow large size and

away from open water. These capabilities were made possible by the presence

of a vascular system which allowed these plants to form the first forests

on earth. The vascular system extends from the roots, through the stem and

branches, and into the leaves, allowing efficient transport of water and nutrients

throughout the plant.

All vascular plants have the sporophyte generation as the dominate

stage.

Characteristics of Seedless Vascular Plants:

The presence of a vascular system.

A dominate sporophyte stage

Reproduction is achieved through dispersal of spores.

Plant Diversity Lab and Notes: Station 6

Note: for our class we concentrate on

the Phylum Pterophyta (Ferns)

The fern with which you are familiar are

the dominate sporophyte stage which, like

the small sporophyte moss, produces

spores. Ferns also have a gametophyte

stage which develops from the germinating

spores. However, the fern gametophyte is

very small, about the size of a child’s fin-

gernail.

The fern frond (leaf) may have on its

underside some small brownish spots

called sori (singular :sorus). These consist

of lollipop-shaped sporangia that produce

spores. Each sporangium has thick

walled cells on one side of the sporangium;

upon drying, these thick-walled cells con-

tract, causing the sporangium to tear open

and then violently fling the spores from the

plant. (Catapult-style)

Plant Diversity Lab and Notes: Station 7

Plant Diversity Lab and Notes: Station 8

Why have seed– producing plants been so successful?

1) The plant can remain dormant as a seed until conditions are favorable for growth. ( In the desert, this

can last for years)

2) By creating a seed, these plants do not need water to reproduce. The

sperm are contained within pollen grains that travel through the air.

3) Seeds can be dispersed more efficiently than spores. The seed is a rug-

ged package for dispersal. Within the tough seed coat is a plant embryo as well

as stored food for the embryo to use in resuming growth when getting estab-

lished.

Plant Diversity Lab and Notes: Station 9

Pro’s More distribution More Created Carried through wind/water

Con’s No protectionAt mercy of the environment

Pro’s Protection Food Supply

Con’s Less created

Plant Diversity Lab and Notes: Station 10

Characteristics of

Gymnosperms:

The pollen grains and

ovules are produced in

CONES

The name gymnosperm

means ’naked seed’.

They do not have their

seeds protected by a

fruit.

Conifers

Conifers produce cones in the spring– male cones

and female cones. The small non-woody male cones pro-

duce pollen grains. All pollen grain is a microscopic male

gametophyte that contains only 3 cells. One of which is

the sperm.

The larger female cones produce ovules, each con-

taining a microscopic female gametophyte containing an

egg. The ovule will develop into a seed after pollination.

Conifers rely upon wind to bring the pollen grains to

the female cones AND to carry away the seeds.

Plant Diversity Lab and Notes: Station 11

Hi! I’m a male cone.

Hi! I’m a female

cone.

Note: Most conifers are ‘evergreen’ and do not drop their leaves in the winter when it is

cold and a lot of the water is tied up in snow and ice. The surface are of these needles

are much smaller than tree leaves and has a thick waxy coating.

Plant Diversity Lab and Notes: Station 12

Phylum Anthophyta (Angiosperms)

The most abundant plant phylum. It makes up over

_____________ of plants

Have seeds which contain a protective layer

Includes grasses, flowering trees, shrubs, and flowers.

Evolutionary trait of flowers

Helps attracts animals which transport flower for flower.

90%

Plant Diversity Lab and Notes: Station 13

Flowers Flowers contain ovaries which surround and protect seeds.

After pollination, ovary develops into a fruit which protects the seed and aids in its dispersal.

Fruit - wall of tissue surrounding seed, facilitate seed dispersion over large distances.

Plant Diversity Lab and Notes: Station 14

Flower Diagrams

•1) Sepals - enclose bud before

it opens and protects developing flower; usually green and closely resembles leaves.

Flowers have four kinds of specialized leaves: sepals, petals, stamens, and carpels.

•2) Petals - located inside sepals; brightly colored; attract pollinators.

•3) Stamen - male reproductive

structure Anther: sac where pollen grains are produced

Filament: long, thin stalk supporting anther.

•4) Carpel (pistil) - female reproductive structure

• Ovary: contains ovules (which contain eggs).

•Stigma: sticky surface on top of style where pollen grains often land

•Style: stalk above ovary; supports

Pollination:

Bees are the world’s most important pollinator. They are

attracted to the colourful petals of angiosperms. The petal

colour, and design act as a target leading the bees to the

nectar. It’s basically saying, “Good eatin’ this way!”.

Pollination is a good bi-product of bees just wanting

to eat.

Other good pollinators: Butterflies, hummingbirds,

bats, wasps, moths, and some beetles.

Plant Diversity Lab and Notes: Station 15

Bees don’t see more

colours than humans,

just different shades.

They can see more

ultraviolet colours which

help them on their hunt

for colourful flowers .

Plant Diversity Lab and Notes: Station 16

Diversity of Angiosperms

1. Monocots and Dicots

- Monocots and dicots are named for the number of seed leaves, or cotyledons (the first leaf or first pair of leaves produced by the embryo of the seed plant), in the plant embryo.

- Monocots: 1 seed leaf

(corn, wheat, lilies, palms

orchids).

- Dicots: 2 seed leaf

(roses, daises, clovers,

tomatoes).