Charophytes Green algae closest to plants
Dec 24, 2015
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