Charophytes

Green algae closest to plants

Plant Diversity

Plant Evolution

Evolution of structures for better survival on land

Bryophytes – mossesSeedless Vascular Plants – fernsGymnosperms – conifersAngioserms – flowering plants

Bryophytes

Examples of bryophytes are mossesNo vascular tissueMust remain moist to surviveWaxy cuticle to prevent dehydrationNo lignin – they do not stand tall, but cover

the ground like a mat

Reproduction Review

Gametes – sperm (pollen) and eggGametes have half the chromosome number which we

call being haploidGametes become haploid through a process called

meiosis.Normal body cells are called somatic cells. These are

all of the other cells of the plant EXCEPT gametes.Somatic cells are diploid, which means they have the

total number of chromosomes.A spore is NOT a gamete. Spores can grow into a

whole organism, gametes must fuse together to form a zygote.

Bryophyte Reproduction

In mosses, there are two parts of the body1. Gametophyte – soft, green, sponge-like

portion of the moss2. Sporophyte – stalk growing out of the

gametophyte

Bryophyte Life Cycle

Life cycle

Start with male and female haploid (n) gametophytes.

Antheridium contain the sperm – at the tip of the leaf

Archegonium contain the egg – at the base of the leaf

Fertilization occurs via water transport – diploid (2n) zygote is formed and grows into a mature sporophyte

Spores undergo meiosis and are now haploid (n).Spores fall to the ground and bud new male and

female haploid (n) gametophytes.

Ferns

Ferns

Ferns have vascular tissue – next level of adaptationHowever, their sperm still swim like mosses12,000 different speciesFound in the tropics and temperate forestsDate back to 360 MYA – carboniferous periodThe remains of these plants create peat and through

the years heat and pressure turn the peat into coal.Coal is a fossil fuel used to generate much of our

electricity.The most extensive coal beds are from the

carboniferous period.

Fern Life Cycle

Fern Reproduction

Sorus on the underside of the leaf hold spores

Spores germinate into haploid gametophyte

Antheridium holds the sperm and archegonium holds the egg.

Fertilization occurs through water

New diploid sporophyte begins to grow.

Gymnosperms

Gymnosperms

Near the end of the Carboniferous period, the climate became cool and dry.

Lots of ferns and mosses began to dieGymnosperms become very successful because

of seed productionConifers are the most diverse gymnosperms –

pines, spruces, firs, and redwoodsThick cuticle on the leaves, stomata in pits to

prevent water lossReduction of gametophye, pollen in cases, and

seeds are also adaptations to life on land.

Pine Cones

Gymnosperm Reproduction

Gymnosperm Reproduction

Male pollen - microspore undergo meiosis (n)

Megaspore mother cell is in the pine cone and undergoes meiosis (n)

Pollen fertilizes egg in the archegonium

Creates embryo which is the young sporophyte (2n).

Sporophyte grows into mature tree.

Coniferous Forests

190 million acres are designated national forest

Loss of forests due to grazing, lumber industry, mining, and public recreation.

Conifers of Yosemite

Incense Cedar

Angiosperms

Flowering plantsDominate most of the Earth250,000 species Wheat, corn, oats, barleyCitrus, fruit, vegetablesCotton, flaxCherry and walnut furniture Vascular adaptations make it easier for

angiosperms to live on landFlowers are why they are so successful.

Structure of a flower

A flower is composed of four whorls

1. Sepals – green parts that enclose the flower before it opens

2. Petals – attractive part of the plant that attracts birds and bees

3. Stamen – anther and filament

4. Carpel – stigma, style and ovary

Angiosperm Life Cycle

Angiosperm Life cycle

Mature sporophyte (2n) contains pollen and egg.

Pollen and egg undergo meiosis and become haploid (n).

Pollen is released and carried to the stigma (sticky)

2 Pollen travels down the style to the ovary.

Double fertilization occurs creating a zygote and endosperm

Endosperm is the food for the growing diploid embryo (2n).

Fruit

Now the ovary is called the fruit and the ovule is called the seed.

The seed will grow into a new mature sporophyte (2n).

Examples of seed dispersal

Medicines derived from plants

CAM plants

Succulents – pineapple, cacti, jade plantCAM plants open their stomata only at night

to let CO2 in and O2 out.CO2 is packaged in a 4-Carbon compound

and released to calvin cycle during the day.Only open the stomata at night to prevent

water loss.

Jade Plant