Brent Cornell

    
Plants can reproduce in a number of different ways:

• Vegetative propagation (asexual reproduction from a plant cutting)
• Spore formations (e.g. moulds, ferns)
• Pollen transfer (flowering plants – angiospermophytes)

Sexual reproduction in flowering plants involves the transfer of pollen (male gamete) to an ova (female gamete)

• This involves three distinct phases – pollination, fertilization and seed dispersal

Pollination:

• The transfer of pollen grains from an anther (male plant structure) to a stigma (female plant structure)
• Many plants possess both male and female structures (monoecious) and can potentially self-pollinate
• From an evolutionary perspective, cross-pollination is preferable as it improves genetic diversity

Fertilisation:

• Fusion of a male gamete nuclei with a female gamete nuclei to form a zygote
• In plants, the male gamete is stored in the pollen grain and the female gamete is found in the ovule

Seed dispersal:

• Fertilisation of gametes results in the formation of a seed, which moves away from the parental plant
• This seed dispersal reduces competition for resources between the germinating seed and the parental plant
• There are a variety of seed dispersal mechanisms, including wind, water, fruits and animals
  • Seed structure will vary depending on the mechanism of dispersal employed by the plant

Plant Reproduction Stages

    
Cross-pollination involves transferring pollen grains from one plant to the ovule of a different plant

• Pollen can be transferred by wind or water, but is commonly transferred by animals (called pollinators)

Pollinators are involved in a mutualistic relationship with the flowering plant – whereby both species benefit from the interaction

• The flowering plant gains a means of sexual reproduction (via the transference of pollen between plants)
• The animal gains a source of nutrition (plants secrete a sugar-rich substance called nectar to attract pollinators

Common examples of pollinators include birds, bats and insects (including bees and butterflies)

• Flowers may be structured to optimise access for certain pollinators (e.g. tube-shaped flowers for birds with long beaks)

Cross-Pollination