Introduction to Plants

Learning Intention 1

Explain the Life Cycle of Flowering Plants

Identify where the processes of Germination and Photosynthesis fit in to the life cycle of plants

Explain the significance of germination and photosynthesis to the life cycle of plants

Flowering Plants

BBC The Private Life of Plants - 03 - Flowering - video DailymotionWatch BBC The Private Life of Plants - 03 - Flowering - Educational documentaries on Dailymotion

Life on our planet needs water, carbon, most often oxygen, and Energy

Humans drink water or things containing water, we breath oxygen, and we eat carbon based foods that contain chemical potential energy

Plants are the same, they need oxygen for cellular respiration (yes, they need carbon dioxide too for photosynthesis)

Plants also need carbon, they get this carbon during photosynthesis, turning it into glucose and then into starch and fiber

Plants also need water. This is why drought is bad, and why you need to water your pot plants

And plants need Light for Energy, though they also use chemical potential energy

Life, as defined by MRSGREN, also needs to reproduce. To pass the fire of life along though time.

To do this they must reproduce

The reproductive parts of flowering plants are their flowers. The pollen contains the sperm, the ovum contains the ovule.

The pollen needs to get from one flower to another - this is called pollination

Pollen can get to the other flower either though the wind, or by pollinators (organisms that carry pollen). Pollinators include insects, such as bees (so save the bees), birds like the Tui (think kowhai trees) and bats (like Mrs Simpsons Cactus)

Once the pollen lands on the stigma (the middle stalk of the flower) it forms a tube called a pollen tube, this goes all the way down to the ovary and then to an ovule (egg)

Once Fertilized the ovule becomes a seed and the ovary becomes a fruit (so the flower becomes a fruit)

Well, not always. Fruiting is just one type of seed dispersal. With fruit, something eats the fruit then deposits the seeds in manure hours or a day later.

Other ways that seeds can be dispersed is in seed pods, by making the seed really big and floating - coconuts and mangroves. Seeds can grow little hooks on them and be dispersed on the feet of people and animals - think prickles in you back yard. Or the seeds can float on the wind like swan-plants.

Seeds can remain dormant (nothing happening) until they land in the right conditions

The right conditions are a place that is warm and has water.

The right place is signaled by water entering the seed through the micropyle.

The moisture then allows enzymes to start to float around, and start to work

Thus begins Germination

The seed then sends out a radicle , this senses gravity (geotropic) and grows downward, it becomes the root ,to anchor the plant and to start absorbing more water

The plumule also senses gravity, it pushes upwards to find the sun and to start photosynthesis

The Cotyledon shrinks as the food store is used up and the chemical potential energy and carbon in here is used by the growing plant. Once the plant starts to photosynthesis, the cotyledon will no longer be need as the plant will be using solar energy and will be creating its own food (as it is an autotroph)

Then the new plant is a seedling

It grows, respires, moves in response to the sun and other stimuli, it senses the sun, and it senses gravity, it excretes nitrogenous waste into old leaves that fall away, and it gains its nutrition mostly from water and carbon dioxide

Then when it reaches maturity, it forms flowers and the cycle starts again

PlantsScience education resources related to the topic Plants

Flowering plant life cyclesThe flowers and fruit of flowering plants come and go as part of their life cycle. Some flowering plants don’t even have stems and leaves all the time. The fruit and vegetables we eat come from different parts of the life cycle of various plants, such as roots, stems, leaves, flowers, fruit and seeds. There is a good botany lesson to be found in food on our plate, which may include a few surprises. For example, if it has seeds in it, to a botanist it is a fruit – that includes tomato, pumpkin and cucumber.

Evolution of Plants - from Moss to Flowers

First in the Plant Kingdom there was a type of green Algae that falls into the classification of Charophytes (there is also non-plant algae)

Then Plants moved to the land, where we get moss, aka, Bryophytes

Next come the plants that have their own circulatory system, the vascular plants, the Ferns aka Pteridophytes

Then the plants that uses Seeds instead of spores, the Gynosperms (eg Pine trees, Kauri trees - Great Kauri Trees)

Then finally, we arrive at the Angiosperms - these have flowers and fruit (eg orange trees, kowhai, look A pohutukawa tree: www.youtube.com/watch?v=K5AM2nrxAq4

Angiosperms can then be divided again into: Monocots and Dicots (Dicots are also called aka eudicots)

Monocotyle = has one cotyledon in it's seed

Dicot = has two cotyledon in it's seed

A cotyledon is a immature leaf that fills up most of the seed and is used as food by the embryo

To put it another way

First plants in water = green algae = Charophytes
Plants move to land = moss = Bryophytes
Plants develop vascular tubes = ferns = Pteridophytes
Plants use seeds = pine trees, Kauri = Gymnosperms
Plants use flowers = Pohutukawa = Angiosperms
Angiosperms split
1. Monocotyledonous (Monocot for short)
  1. grasses, cabbage trees, banana, corn, rice, Harakeke flax, wheat
  2. most common edible grains = Monocot
2. Dicotyledonous (Dicot for short)
  1. Pohutukawa, kowhai, rata, beech, oranges, apples, tomato, watermelon
  2. most common edible fruit = Dicot

What is a plant?What do you think of when asked to visualise a plant? Is it the feed crop growing in the paddock next door or a large kauri tree growing in a forest? Is it a tiny microscopic alga or the potted plant in your classroom? All these and more are indeed examples of plants!

Monocots vs Dicots ExplainedA big thanks to all current and future patrons who are helping fund this science and filmmaking outreach via Patreon: http://bit.ly/2Sfmkph Don’t forget to f...

New Zealand Dicot and Monocot examples

New Zealand’s Flora

www.tiritirimatangi.org.nz/monocots-and-grasses

Vascular plants

Learning Intention 2

What are the key structures and functions of a flower?

Draw and label a diagram of a flower including:
- Stamen
  - Anther
  - Filament
- Pistil/carpel
  - Stigma
  - Style
  - Ovary
  - Ovule
- Petal
- Sepal
- Nectary

Flower Parts

Stamen = men bit = consists of an Anther, like how a stag has an antler, and a filament
- The Anther contains pollen, the filament holds the anther out

The Pistil or Carpel is the female bit
- It consists of a sticky stigma, for the pollen to land on.
- The long style, through which the pollen tube must grow down through
- The Ovary which contains the Ovules.
- Once fertilized the Ovules become seeds and the Ovary becomes fruit

To attract pollinators the flower has colorful petals and a nectary. The nectary contains sugary water known as nectar

To protect the flower as it develops in the bud, it has Sepals

A Flowers Purpose

The Flower is the reproductive organ of a plant

The purpose of the flower is to make new plants

The purpose of the flower is reproduction

The Flower has pollen, pollen contains sperm cells

The Ovary contains Ovules - these are the eggs

If the sperm meets the egg then you get an embryo forming inside what becomes a seed. The seed can grow into a new plant - thus propagating that plants genetic lineage

The movement of Pollen from the Anther to the Stigma is Pollination. This may be done in the same flower, which is self-pollination, or from the flowers of different plants of the same species, this is cross-pollination.

For cross-pollination, the mechanism to move the pollen may be the wind, or it might be an organism

Learning Intention 3

What is Pollination?

Define pollination
Stage the differences between self-pollination and cross-pollination
Describe the benefits and disadvantages of each
Describe the adaptations flowers have in relation to how they are pollinated

www.infocobuild.com/books-and-films/nature/life-of-plants/episode-3.html

Pollination

Pollination is the movement of pollen from the anthers to the stigma

This can occur within the same plant, Self-pollination

This can also occur from different plants of the same species, Cross-pollination

Self-Pollination

A plant has sex with itself

It can occur in the same flower, or from different flowers of the same plant

It can occur without a pollinator, but will requires the wind or an insect to move the pollen from the anther to the stigma.

Both sunflowers and dandelions can self pollinate.

Most self-pollinating plants will also cross-pollinate. For example half of the seeds of a Pohutukawa tree will be fertilized by self-pollination and the other half will be by cross-pollination

Approximately 40% of all flowering plants will both self-pollinate and cross-pollinate

Approximately 50% of flowering plants will only cross-pollinate

Self pollination ensures survival of the species by creating offspring regardless of the presence of pollinators and without the need for other plants.

Self pollination is less energy expensive for the plant as it can have smaller flowers and can produce less pollen.

However, self-pollination reduces genetic variation. This can be fine if the environment doesn't change. However, it will be problematic should the environment change.

Less expensive for the plant, as the flowers can be smaller and less pollen needs to be produced., It also helps to reduce variation

The disadvantage is there is less tolerance to environmental and pathogenic change

Advantages

quick
ensures plant population in the absence of pollinators and in the absence of other plants

Cross-Pollination

Cross pollination occurs when the pollen from one plant lands on the stigma of another plant (of the same species)

This results in greater genetic diversity - much like in animal populations

This method is what drives evolution. As it increases the likelihood of the species surviving if the environment changes. (survival of the fittest)

Mechanisms to increase the likelihood of cross pollination are:

Stigma protruding out past the stamen
Having the stamen and stigma mature at different times

Advantages

increased diversity - increased survivability of the species should environment change

Preventing Self-Pollination

Perfect flowers have both male and female organs, so plants have strategies to avoid self-pollination:

1.Timing – male and female structures mature at different times

2. Morphological – structure of male and female organs prevents self-pollination (imperfect flower)

3. Biochemical – chemical on surface of pollen and stigma/style that prevent pollen tube germination on the same flower (incompatible)

In the example below the plant has the alleles s1 and s2, only pollen that does not have those alleles can form a pollen tube

Pohutukawa

The Pohutukawa tree employs self pollination incase a seed should end up on a beach far from other Pohutukawa trees. Thus it can establish a colony of trees. Once established though, cross pollination is preferred. This preference is achieved by the cross-pollinated seedlings growing faster than the self-pollinated seedlings, thus the cross out compete the self.

Pollination | ecologyPollination, transfer of pollen grains from the stamens, the flower parts that produce them, to the ovule-bearing organs or to the ovules (seed precursors) themselves. In plants such as conifers and cycads, in which the ovules are exposed, the pollen is simply caught in a drop of fluid secreted by

The science of fruit-tree pollinationIf you want fruit, you need to understand your fruit tree’s distinct pollination needs

Plant pollinationDr Mark Goodwin of Plant & Food Research explains how flowering plants use self-pollination or cross-pollination in their reproduction. He uses kiwifruit and avocado as examples to show how some plants avoid self-pollination. The functions of pollen and nectar are also explained.

Brush up on anthers, stigmas, florets, and insects with a self- and cross-pollination guideSome of the different ways plants are pollinated.

Pollinators

A pollinator is something that moves pollen from the Anther to the Stigma
Pollinators can be abiotic or biotic
Biotic pollinators include the birds and the bees

Methods of pollinationFlowering plants need to get pollen from one flower to another, either within a plant for self-pollination or between plants of the same species for cross-pollination to occur. However, pollen can’t move on its own, so animals or the wind (and water in rare cases) move the pollen for plants.

Abiotic Pollinators (mostly wind)

98% of all abiotic pollination is by the Wind

Plants that are pollinated by the wind will:

Produce large amounts of pollen
Have large stamen that protrude out of the flower
Have dull flowers

Top 7 sneeziest plants of New ZealandYou can blame these hay fever-inducing plants for your misery.

New Zealand Beech Tree

Beech forestNew Zealand's beech forests are made up of five species of southern beech.

The main trees in NZ South Island Forests are Beech Trees

These are wind pollinated trees

These Beech trees have small flowers that have very large red Anthers

The Stigma forms after the Anthers to reduce self pollination

The Beech Tree is an example of a NZ Wind pollinated tree

After pollination, the ovary forms a 'nut' that is wind dispersed and is food for birds

Biotic Pollinator

https://www.nature.com/scitable/knowledge/library/pests-and-pollinators-23564436/

Biotic Pollinators are pollinators that are alive

Insect
- Bees
- Flies
Birds - like the Tui
Bats
Geckos

Plants that are pollinated by insects and birds will usually have a colorful petals to attract the pollinators as well as a smell to attract them

Often co-evolution will occur in which the plant and pollinator evolve in unison

Why do flowers smell?Most gardeners know that plants produce scents to entice pollinators, but there’s more to the complex relationship between plants and scent than meets the nose.

The prettiest pollinators: A guide to rare and common butterflies of New ZealandIn New Zealand, there are 46 species of butterfly which are found nowhere else on earth. How many have you seen?

Bird pollination in New ZealandDave Kelly of the University of Canterbury explains abiotic pollination by wind and biotic pollination by animals. He shows the characteristics of bird-pollinated flowers and the birds that carry out their pollination, with footage of tūī and bellbird feeding. Dave also explains the meaning of the ecological term ‘mutualism’.

Wind vs Biotic Pollination

Toetoe

Wind pollinated Flax

Long stamen to catch the wind
Large amounts of pollen

Harakeke

Bird pollinated Flax

bright colorful flowers
small stamen with sticky pollen that attaches to the tui's beak

Learning Intention 4

What is fertilization?

Define fertilization
State the differences between cross and self-fertilization
Describe the benefits and disadvantages of each
Describe the stages of fertilization:
- pollen tube
- microphyle
- sperm
- ovule
- zygote
- endosperm

Fertilization

Fertilization is when two gametes fuse to create a zygote

Gametes = sex cells = made via Meiosis = sperm and egg cell
Zygote = first cell of a new organism

Self-fertilization vs Cross-fertilization

Self-fertilization and cross fertilization is a result of self-pollination and cross-pollination.

Self-fertilization

Self-fertilization is the result of self-pollination. So, the plant is breeding with itself.
The benefits are rapid proliferation of the plant in a new location.
Self-fertilization results in a small amount of variation due to independent assortment of chromosomes and cross over.
This small amount of variation means that the plant species is more specialized to its niche and less able to adapt to changes in the environment
By variation, I mean that if a plant with white flowers self pollinates then self fertilizes itself, then all of its offspring will have white flowers

Cross-fertilization

Cross-fertilization is the result of cross-pollination. So, the plant is breeding with other plants
Its benefits are genetic diversity, and thus greater physical diversity within its species. This makes its species more likely to survive should the environment change.
By variation, I mean that if a plant with white flowers cross pollinates and cross fertilizes with a plant that has red flowers, then its off spring might have white flowers, red flowers, pink flowers, or even orange flowers

Plant Fertilization

After the birds and the bees

Fertilization is the step after pollination.

For fertilization to occur, the pollen that landed on the stigma during pollination now needs to grow. The steps are listed below:

The sugar on the stigma stimulates the pollen tube to grow - and provides nutrients for this growth
It grows a pollen tube down the style of the other plant
The pollen tube grows though the style by releasing digestive enzymes at its leading edge that digest the style
The pollen tube then absorbs the nutrients, using them to sustain its own growth
The sperm cell travels down the pollen tube to the ovary, then to the ovule
The pollen tube combines with the ovule at the microphyle
The male gamete, the sperm leaves the pollen tube and enters the ovule at the microphyle
In the ovule, the sperm cell will meet the female gamete, the egg cell, creating a zygote.
The ovule will now develop into the seed

Double Fertilization

This is what usually happens in flowering plants (Angiosperms) for both monocots and dicots

Two sperm cells are released from the pollen tube at the microphyle
One sperm cell combines with the egg cell creating a zygote
One sperm cell goes to the two polar nuclei within the large central cell in the middle of the ovule - most of the ovule or embryo sac is this large central cell
Once here the now three nuclei fuse together creating the endosperm nucleus
The endosperm develops as a food reserve for the embyro
The zygote becomes the embryo