Evolution of Australian Biota Describe the mechanisms used by Australian Flora for Pollination, Seed Dispersal and Asexual Reproduction

Pollination  Definition: The transfer of pollen grains from the anther to the stigma  Two different processes: Self-pollination and Cross- Pollination  Two main groups of land plants involved:  Gymnosperms(cone- bearing plants)  Angiosperms(flowering plants)

Pollination  Self-Pollination: occurs within the same flower  Cross-Pollination: the transfer occurs with another plant of the same species  This allows for increased variation in species  Methods of Pollination:  Through wind  By insects  By other animals

Pollination  By wind:  Usually cone-bearing or dull-coloured flowering plants.  The increased surface area enabled by the feathery stigma allows for a higher chance of pollen landing on it.  Stamen droop outwards in order to increase wind exposure.  An Australian example of a wind pollinated plant is the Themeda triandra (Kangaroo Grass).

Pollination  By insects:  Most insects initially source pollen by odour however they can also be attracted by plants by their shape, colour and texture.  Some native flowers grow in inflorescences (clusters) which attracts insects and improves pollination efficiency.  An Australian example is the Lamberta formosa (Mountain Devil), form inflorescences, are rich in nectar and brightly colour drawing in bees.

Pollination  By other animals:  Other animals that are known to pollinate include possums, bats and small rodents.  An Australian example of a plant that is pollinated by an animal it the Dryandra quercifolia (Oak- leaved Dryandra) which is pollinated by the Australian Honey Possum (Tarsipes rostratus).

Seed Dispersal  Definition: the ability for a plant to spread its seeds over a wide distance in order to reproduce  Five main seed dispersal adaptations:  Wind  Animals  Fire  Water  Explosion

Seed Dispersal  By wind:  An common adaptation which seeds dispersed by wind have are tiny wings, blades, parachutes etc.  An Australian example of a wind dispersed seed is the Banksia ericifolia (Heath-leaved Banksia).

Seed Dispersal  By animals:  Seeds which are dispersed by animals have various features in order to be dispersed. These include:  Hooks and barbs to cling onto fur and feathers  They are brightly coloured which attracts animals, particularly birds  Passing through the digestive systems of animals  An Australian example of a seed which is dispersed by animals is the Nitraria billardieri (Nitre Bush) which relies on the digestive system of an emu in order to germinate.

Seed Dispersal  By fire:  Seeds are stored in the plant until fire burns up the organism.  Seed pods open due to the intense heat and then the seeds inside are dispersed via wind.  An Australian example of a seed that is dispersed by being burned is the Banksia prionotes (Acorn Banksia).

Seed Dispersal  By water:  Seeds float upon the currents of rivers, estuaries and seas in order to disperse.  An Australian example of a water dispersed seed is the Syzygium francisii (Water Gum).

Seed Dispersal  By explosion:  Some seeds violently explode from the pod of a plant, which cause the seed to vastly disperse itself. This is caused by the contraction and drying of the plant pod.  An Australian example of this is the Acacia cultriformis (Knife- leaf Wattle) which can disperse itself up to 2 metres via explosive dispersion.

Asexual Reproduction  Definition: reproduction which is brought about by mitosis  Offspring are genetically identical to their parents providing little opportunity for variations in a species  Three types of asexual reproduction:  Budding  Vegetation Reproduction  Apomixis

Asexual Reproduction  By budding:  An asexual reproduction process where an organism can develop from outgrowing it’s parent plant.  An Australian example of budding is the Kalanchoe which can produce buds along the sides of its leaves which will eventually outgrow, ground themselves in soil and reproduce.

Asexual Reproduction  By vegetation reproduction:  An asexual reproduction process where flora is cloned from adult cells using rhizomes, suckers and runners DefinitionExampleImage RhizomesHorizontal stems which root themselves underground, near the parent plant, in order to germinate Anigozanthos flavidus (Tall Kangaroo Paw) SuckersSprout-like shoots which are produced at the end of plant roots and can dispatch to reproduce Phragmites australis (Common Reed) suckers in aquatic habitats RunnersLong, thin stems which reproduce on the top of soil Spinifex hirsutus (Spinifex Grass) produce plantlets on soil surfaces

Asexual Reproduction  By apomixis:  The asexual reproductive process where the embryos in the seeds are produced separate, however are still identical to, the parent cell.  This process also has the advantage as a method of seed dispersal.  An Australian example of apomixis is the Citrus limon (Lemon Tree).