Evolution

•  Flowers
  

The flowers, which are the reproductive organs of flowering plants, are the most remarkable feature distinguishing them from other seed plants. Flowers aid angiosperms by enabling a wider range of evolutionary relationships and broadening the ecological niches open to them. This has allowed flowering plants to largely dominate terrestrial ecosystems.

• Stamens with two pairs of pollen sacs

Stamens are much lighter than the corresponding organs of gymnosperms and have contributed to the diversification of angiosperms through time with adaptations to specialized pollination syndromes, such as particular pollinators. Stamens have also become modified through time to prevent self-fertilization, which has permitted further diversification, allowing angiosperms eventually to fill more niches.

• Reduced male parts, three cells

The male gametophyte in angiosperms is significantly reduced in size compared to those of gymnosperm seed plants. The smaller pollen decreases the time from pollination – the pollen grain reaching the female plant – to fertilization of the ovary; in gymnosperms fertilization can occur up to a year after pollination, while in angiosperms the fertilization begins very soon after pollination. The shorter time leads to angiosperm plants setting seeds sooner and faster than gymnosperms, which is a distinct evolutionary advantage.

• Closed carpel enclosing the ovules (carpel or carpels and accessory parts may become the fruit)

The closed carpel of angiosperms also allows adaptations to specialized pollination syndromes and controls. This helps to prevent self-fertilization, thereby maintaining increased diversity. Once the ovary is fertilized, the carpel and some surrounding tissues develop into a fruit. This fruit often serves as an attractant to seed-dispersing animals. The resulting cooperative relationship presents another advantage to angiosperms in the process of dispersal.

• Reduced female gametophyte, seven cells with eight nuclei

The reduced female gametophyte, like the reduced male gametophyte, may be an adaptation allowing for more rapid seed set, eventually leading to such flowering plant adaptations as annual herbaceous life cycles, allowing the flowering plants to fill even more niches.

• Endosperm

Endosperm formation generally begins after fertilization and before the first division of the zygote. Endosperm is a highly nutritive tissue that can provide food for the developing embryo, the cotyledons, and sometimes for the seedling when it first appears.
These distinguishing characteristics taken together have made the angiosperms the most diverse and numerous land plants and the most commercially important group to humans. The major exception to the dominance of terrestrial ecosystems by flowering plants is the coniferous forest.

Thanks to Wikipeida 

Plants & History

Ever since Early Man rubbed two sticks together to make fire, plants have played a vital role in the history of mankind.
The cultivation of grain changed nomads into village dwellers, wooden boats allowed civilisations to explore new lands, and precious spices were used from earliest times to trade between nations. Later on, it was Christopher Columbus’s search for new spice routes that led to his discovery of the Americas and their colonisation by Europeans.
Plants have been used as medicines, but also as instruments of death. The famous Greek philosopher Socrates drank hemlock when sentenced to death in ancient Athens. The Roman emperor Claudius was murdered using a plate of lethal mushrooms.
A plant allegedly even influenced the laws of physics! Our understanding of the way that gravity works came about because Isaac Newton saw that apple fall in 1665!
Plants have had far-reaching effects on many civilisations, the impact of which we still feel today. The slave trade arose out of the need to supply the sugar cane plantations in the West Indies with cheap labour. And the failure of the potato crop due to blight was a contributory factor in the Irish famine of the 1840s, which in turn led to mass emigration to America.

See the top 10 plants that we think have made the biggest difference to this category.

Thanks to: http://www.plantsandus.org.uk

Photosynthesis

Photosynthesis

Part 1 : Introduction

* When you get hungry, what do you do? You might decide to raid the refrigerator or try to convince your mom to take you to a fast food restaurant. You do those things because you are a heterotroph (or consumer). Heterotrophs are organisms that need to get their energy from the foods they eat. Humans and animals are heterotrophs — so are parasites like fleas, ticks, and tapeworms!
Conifers, like other green plants, can't just reach in the fridge for a quick snack. They have to make their own food. Green plants are called autotrophs (or producer). Autotrophs use light energy from the sun to produce the food they need. To understand how this works, we need to learn about photosynthesis.

Bio4Kids

* Photosynthesis takes place in the chloroplasts in plant cells. Chloroplasts contain a green substance called chlorophyll. This absorbs the light energy needed to make photosynthesis happen. Plants can only photosynthesise in the light.

Chloroplast

Part 2 : The Process

* Photosynthesis is a process. It's a set of steps that happen in a certain order inside the cells of green plants. Let's think of photosynthesis as a recipe — the plant version of a making a batch of chocolate chip cookies!
Before you begin cooking, you need to be sure you have all of the ingredients. Then you can get started! It's the same with plants.

* There are many things that the plants need for Photosynthesis:
Carbon Dioxide
Water
Sun Light

1- The chlorophyll in the cell of the plant absorbs light from the sunlight.

2-The sun's energy splits the water molecules into hydrogen and oxygen.

3-The hydrogen joins with carbon dioxide to make sugar (Food)

4- The sugar is carried to other parts of plant.

Note that: The extra oxygen is released into the air

* With every process there is a result :
Oxygen
Glucose

* Without chlorophyll a plant would not be able to make the food it needs. Chlorophyll is a pigment found in green plants. It's what makes the needles of a TREE look green.
Chloroplasts are special parts of most green plant cells. They are where you find chlorophyll.
This is where the action of photosynthesis takes place.

Leaf

Plant Organs

Structures of flowering plants are well-adapted to varied environments, including water.

The body of a vascular plant is organized into two general kinds of organs: a Root System (the roots) and a Shoot System (the stems and leaves) . These organs all contain tissue systems, but they differ in the way the cells are specialized to carry out different functions.

Roots, stems, and leaves are the vegetative organs of plants; flowers, seeds, and fruits are reproductive structures.

EMC

Root System

A plant's root system is underground.
The root system is primary root plus the branch roots.
It is generally equal in the size of the shoot systems, the part above ground.
Root systems have the following functions:

• Roots anchor a plant in soil and give support.
• Roots absorb water and minerals from soil, root hairs are central to this process.

* Root hair cells are in a zone near the root tip.
* Root hairs are numerous to increase the absorptive surface of a root.
* Transplanting plants damages a plant when the root hairs are torn off.
* Water and nutrients absorbed are distributed to the plant.
* Roots produce hormones the must be distributed to the plant.

Perennials "Die Back" to regrow the next season; root of herbaceous perennials store food (carrots, sweet potatoes)

UIC

Shoot System

The shoot system is above ground and includes the organs such as leaves, stems, and the branches.

Stems

1. The stem forms the main axis of the plant, along with lateral branches.
2. Upright stems produce leaves and array them to be exposed to as much as possible.
3. A node occurs where a leaf attaches to the stem and an internode is the region between nodes; nodes and internodes identify a stem even if it is underground.
4. The stem has a vascular tissue to transport water and minerals from the roots and the sugar form leaves.
5. Nonliving cells from a continuous pipeline through vascular tissue.
6. A cylindrical stem expands in girth and length; trees use woody tissues to strengthen stems.
7. Stems may function in storage : cactus stems store water and tubers are horizontal stems that store nutrients.


Leaves

1. A leaf is the major organ of photosynthesis in most plants.
2. Leaves receive water from roots by way of the stem.
3. Broad, thin leaves have a maximum surface area to absorb CO2 and collect solar energy.
4. A blade is the wide portion of a leaf with the most photosynthetic tissues.
5. The petiole is a stalk that attaches a leaf blade to the stem.
6. the leaf axil is the upper acute angle between petiole and stem where an axillary (lateral) bud originates.
7. Some leaves protect buds, attach to objects (tendrils), store food (bulbs), or capture insects.

-=-=-=-=-=-=-=-=-=-=-
Questions:

1. Name the two general kinds of organs of a plant?
2. Name one function of the following : Root - Leaves - Stems
3. What is Perennial ?
4. Why the stem has a a vascular tissue?

Plant Basics

If you're not a microbe and you're not an animal, chances are you are a plant. There are loads of species of plants on Earth. Just as there is a system of classification for animals, there is also a system of classification for plants. Because plants adapt so well to any climate, scientists need a way to organize the hundreds of thousands of species.

Welcome Massage

Welcome

I hope you enjoy the course