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Plant reproduction and Growth
Transcript of Plant reproduction and Growth
Pollination in an Acacia
Structural adaptations for pollination and seed dispersal of an Acacia
The Acacia has taken on the structural adaptations of a brightly coloured flower and legumes to attract animals to pollinate the plant along with scented flowers. These adaptations are what draw the animals in along with the nutritionally rich nectar. The plant is also resistant to heat and lack of water to handle harsh weather conditions.
Pollination of an Pink Hyacinth orchid
Pollination of a Pink Hyacinth orchid begins when the insects pick up pollen from one flower and carry it with them to another orchid flower of the same species nearby. It is these pollination mechanisms, resulting in such beautiful flowers.
Structural adaptations for pollination and seed dispersal of an Pink Hyacinth Orchid
The Pink Hyacinth Orchid has taken on the structural adaptations for pollination and seed dispersal by attracting pollinators in three different ways - offering nectar as a reward to visiting insects, by appearing to offer nectar as a reward (called visual mimicry), or by sexual mimicry in which orchid flowers have evolved to look like, and in some cases smell like, female insects which results in the attracting of male insects of the same (or very closely related) species to land on them and attempt to mate with them. This causes the insects to brush against the plant and away take some pollen with it until it reaches the next plant of the same species where it rub's its pollen off onto that plant resulting in pollination and germination.
Pollination in an Acacia occurs due to insects such as; beetles, wasps and bees pollinating the nectar to other Acacia plants. However, the native Australian bee along with the European bee are the common pollinators of the plant.
What is Pollination?
Pollination is the transfer of pollen from an anther of male to the stigma of a female plant. This can be done by wind, animals, insects or by hand in artificial pollination.
What is seed dispersal?
How does pollination occur?
Pollination occurs in flowering plants by the male gametes from the male anther to the female stigma. A pollen tube will then grow down through the female style and into the female ovule where fertilization occurs.
Gametes- Sperm in pollen
For species to survive, their seeds must be widely dispersed away from themselves to prevent overcrowding and to create new colonies in areas suitable for their germination and survival.
How seed dispersal occurs
Catching a lift
Drop and roll
Some plant's have adapted to using wind dispersal by having small seeds which can be carried away with the wind; Such as sycamore "Helicopters" or dandelion "clocks".
The seeds of the plant suddenly bursts open trowing the seeds in all directions; Such as, peas, laburnum or gorse.
Some plants dry out and contain little holes all around the top like a poppy seed head. These type of plants shake with the wind which causes the seeds to be thrown out of the plant through the holes.
Some plants are situated near water and when there seeds fall off they are carried away by the water current to an area where they can germinate. An example of this is coconuts.
Animals brush past plants which contain seeds know as burrs and distribute them to a new site. The burs get caught on the animal’s fur or feathers due to the barb like structures which allow it to get tangled easily. Bathurst bur is an example of such a plant.
Some animals eat fruit which contain seeds, these seeds are eaten by the animal and travel through their digestive tract where they are then disposed of with the animal’s faeces in a new area.
Drop and roll is the simple seed dispersal of seeds simply dropping from the plants they come from and rolling away to another area nearby to germinate as a colony.
Adaptations for pollination and seed dispersal
Plant life takes on adaptations over a period of time to ensure the survival of a species and sufficient germination. Plants take on specific traits to adapt to the conditions and environment around them.
This is done through the plants developing attributes of brightly coloured flowers and specific smells (e.g. strong lavender smell) to attract the same type of species or animal to the flower (e.g. a bee).
The plants seeds also adapt features such as being covered in sweet fruit, light weight or having a barb like structure to enhance the possibilities of animals catching the seeds in their fur or feathers or being eating and released by the animal as faeces in a new location. It also creates the option of the plant being self-pollinated or cross-pollinated.
Is fertilization by transfer of pollen from the anthers to the stigma of the same flower.
Is fertilization by transfer of pollen from the anthers of one flower to the stigma of another.
Cross-pollination is a much more advanced way for a plant to pollinate as the plant produces more seeds to disperse and germinate.
Neither self-pollinating or cross-pollinating plants can be pollinated by pollen of a plant from another species. (e.g. an apple tree cannot pollinate a rose.)
Plants have adopted features to prevent being given pollen or trying to pollinate with other species such as; smell and colour of flowers to attract specific species of birds and insects to transport their pollen to another plant of the same species.
These types of adaptations ensure that the plant is being pollinated by the same species of plant and not being insufficiently by another species.
Adaptions for the prevention of pollination by 'non-species' pollen
Acacia's disperse their seeds by bursting as the heat of the sun influences the legumes to eject the seed as it opens up. In some cases however the seeds may remain hanging by the brightly coloured red to orange legume. These bright colours attract birds which then digest the seed and allow it to germinate else where.
Seed dispersal in an Acacia
Adaptations for the prevention of pollination by 'non-species' pollen of an Acacia
Acacia's have a lot of sub-species that are similar; however, Acacia's have developed the adaptation of preventing 'non-species' by having slightly different pollen or nectar along with a difference in physical structure. The pollinators of the Acacia also only really pollinate very different species prveneting such a pollination.
Seed dispersal of an Hyacinth orchid.
Seed dispersal in a Pink hyacinth occurs by wind as there are vast numbers of seeds produced which are light weight and can travel on the wind for thousands of kilometers. These seeds can also be knocked out by insects pollinating the flower causing them to drop or shake out.
By Tissy Elsley 2013
Adaptations for the prevention of pollination by 'non-species' pollen of a Pink Hyacinth Orchid
Adaptations that the Pink Hyacinth Orchid has taken on to prevent the pollination by 'non-species' plants are; the smell and colour along with the choice of unsuccessful cross-pollination the plant can choose to self-pollinate.
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