Transcript Notes - An in depth look at Anthophytes

Kingdom – Plantae
Phylum - Anthophyta
Also known as Angiosperms, or to most
people flowering plants
Anthophyta - Angiosperms
• Produce flowers and form seeds
enclosed in fruit
• Fruit protects the embryo inside the
seed and aids in seed dispersal
• Fruit develops from a flowers female
reproductive structure
2 classes
• Monocots (one seed leaf)
Common monocots – corn, grass, lilly,
and orchid
• Dicots (2 seed leaves)
Common dicots – Maple tree,
tomatoes, potatoes, and dandelion
Can be divided by lifespans
• Annuals (live for one year or less)
Corn, beans, tomatoes, and many food crops
• Biennials (lives for 2 years )
Parsley, carrots, Sweet William, raspberries
• Perennials (can live for several years)
Asparagus, hostas, roses, peonies, coreopsis and many
others
Why flowers?
• location for sexual reproduction in
Angiosperms
• co-evolved with the pollinators
• symbiotic relationship – all species involved
benefit!
Flower Anatomy
• Many sizes, shapes and colors
• Most contain the following organs in some
shape or form
• Petals
• Sepals
• Stamens
• Pistols
Petals
• Usually brightly colored
• Often have perfume or nectar at the base
• Provide surface for pollinators to rest on as
they feed
• All of the petals together are called the corolla
Sepals
• Usually found in a ring at the base or
outermost portion of the flower
• Serve as protective covering for the flower
bud
• All of the sepals together are called the calyx
Stamen – male reproductive structure
• Made up of the anther and filament
• The anther is found at the tip of the filament –
this is where pollen is produced
• The number of stamens varies from flower to
flower
Pistil/Carpel – female reproductive
structure
• Made up of the Stigma, Style and Ovary
The stigma is at the top of the pistil. It’s role is to receive
the pollen
The style connects the stigma to the ovary
The ovary is at the base. It contains ovules that produce
eggs
The number of ovaries varies in flowers
Complete vs Incomplete Flowers
Perfect vs Imperfect Flower
• Complete flowers: pistils, stamens, sepals and
petals
• Incomplete flower: lacking any of the parts
• Perfect flower: has both pistils and stamens
• Imperfect flower: lacks either pistils or stamens
Monoecious vs Dioecious
• Monoecious –separate male and female
flowers on the same plant
• Ex. Corn, pecans, walnuts, cucumbers, and
squash
• Dioecious – separate male and female plants
• Ex. Holly, ginkgo, pistachio, and marijuana
Photoperiodism
• Photoperiodism: response of flowering plants
to daily daylight-darkness conditions
• Ensures all plants of the same species bloom
at the same time
Critical Period
• The specific daylight-darkness conditions that
will make flowering begin
• Day length is not what matters – amount of
darkness is what matters
• The names are misleading – the categories
were named before scientists realized it was
darkness, not light, that prompted flowering
4 Categories
• Short-day: daylight is shorter than critical
period – asters, poinsettias, strawberries
• Long-day: daylight is longer than critical
period – carnations, petunias, potatoes
• Day neutral – flowers over a range of daylight
hours, day length is not what induces
flowering
• Intermediate day – will not flower if days are
longer or shorter than critical period –
sugarcane and grass
Pollination & Fertilization
Aka – the birds and the bees 
Development of the female gametophyte
• Inside the flower the sporophyte produces
haploid spores
• Female spores are megaspores
• The nucleus of the megaspore undergoes
mitosis 3 times to produce the female
gametophyte
• One nucleus becomes the egg, another
becomes the egg, another two become the
central cell.
All of this is taking place inside the ovaries,
which are part of the pistil.
Development of the male gametophyte…so
much simpler than the female
• Microspores are produced inside the anther
• Microspores develop into the male
gametophyte – the pollen grain
• The haploid nucleus undergoes mitosis, but
only once
• One nucleus is the tube nucleus, the other is
the generative nucleus
Now that we have sperm and eggs, how do
we get them together?
• POLLINATION!
• Definition – the transfer of the pollen grain
from the anther to the stigma
• Possible pollinators – wind, water and animals
Adaptations in flowers
Some features that attract animals
– Strong scent
– Nectar
– Bright colors
– Patterns invisible to the human eye
Adaptations in wind pollinated plants
• Lack of petals – no need to waste energy
attracting the wind
• Overproduction of pollen – to make up for the
pollen that never makes it to the stigma
The pollen grain has landed on the stigma,
so what’s next? Double Fertilization!!
Seed Germination
&
Vegetative Reproduction
Seed germination
• Dormancy – the period of inactivity
in a mature seed
• Varies greatly between species
• Ends when the seed germinates
• Germination – the beginning of the
development of the embryo into a
new plant
Germination
• Water, oxygen and warm temperatures
activate the metabolism
• Some seeds have specific requirements
–Ex. Animals digestive system, freezing
temps, extensive soaking in saltwater,
specific daylengths, exposure to fire.
Dicot germination
• Radicle – embryonic root appears
first
• Hypocotyl – portion of stem nearest
seed
• Cotyledon – plants first leaves
• In monocots the cotyledon remains
below the surface
Vegetative reproduction
• A new plant is produced from a
stem, root or leaf
• This is essentially cloning – producing
new plants that are genetically
identical to their parents
• Tissue culture and/or cuttings.
Chapter 24.3
Seeds and Fruit
Why?
• The seeds and fruits formed
help ensure survival of the
next generation
Seed formation
• After fertilization
• Zygote divides = embryo
• Triploid cell divides = endosperm
• Ovule wall = seed coat
Fruit formation
• Fruit – the structure that contains
the seeds of an anthophyte
• Fruit – the enlarged ovary
surrounding the seed
• Can be made up of other organs as
well.
Fruits
• Fleshy fruits – apples, grapes,
melons, tomatoes, cucumbers
• Dry fruits – peanuts, sunflower
seeds, walnuts.
–The ovary around the seeds
hardens
Seed dispersal
• Fruits aid in dispersal
• Dispersal reduces competition
• Animals – digestion and/or carrying
the seed on the body
• Wind – dandelion, tumbleweed
• Water – coconut and water lilies
Pictures – from flower to fruit
• http://www.cas.vanderbilt.edu/bioimages/pag
es/fruit-devel.htm
What about seedless fruit?
• Ex. Watermelon and bananas
• Triploid plants – prevents meiosis
from happening and no gametes are
produced
• So where do the plants come from if
there are no viable seeds?
• Bananas – vegetative reproduction
• Watermelons – Cross a diploid with a tetraploid to
produce a triploid seed
• Diploid (2) + Tetraploid (4) = 6 sets of
chromosomes
• Divide 6 by meiosis to get 3 sets of chromosomes.
• Pollination triggers fruit formation – without seeds.
• The plants must be grown with a diploid variety for
pollen
Seed germination
• Dormancy – the period of inactivity
in a mature seed
• Varies greatly between species
• Ends when the seed germinates
• Germination – the beginning of the
development of the embryo into a
new plant
Germination
• Water – activates the metabolism
• Some seeds have specific
requirements
–Ex. Animals digestive system,
freezing temps, extensive soaking
in saltwater, specific daylengths,
exposure to fire.
Dicot germination
• Radicle – embryonic root appears
first
• Hypocotyl – portion of stem nearest
seed
• Cotyledon – plants first leaves
• In monocots the cotyledon remains
below the surface
Vegetative reproduction
• A new plant is produced from a
stem, root or leaf
• This is essentially cloning – producing
new plants that are genetically
identical to their parents
• Tissue culture and/or cuttings.