Reproduction: How it increases population size

The Birds and the Bees:
    The Macadamia tetraphylla is a seeded vascular plant.  This means that it reproduces via seeds.  In addition, it is part of the group Magnoliopsida, which means that it also flowers and has covered seeds.

    Similar to most (if not all) plants, the Macadamia tetraphylla has an alternation of generations life cycle.  What does this mean?  At multiple points in its life cycle, this plant will have two different multicellular structures.  The sporophyte is the diploid multicellular structure, and the gametophyte is the haploid multicellular structure.  They each have their own respective duties within the plant's life cycle.

     The general life of a plant is as follows: we start as a haploid spore or egg.  The spores are transported via wind, water, or animals- in the case of Macadamia tetraphylla, wind, water, and small rodents like squirrels- to the stigma of the flower.  From there, the spore (which is the sperm cell) makes its way down the style into the ovary of the flower.  Then, it fertilizes the egg inside the ovary and produces a diploid zygote.  The zygote grows into a seed which is then dropped and waits for the right growing conditions.  These seeds can last up to 4-6 months and still be able to produce a plant.  When good conditions arise, the plant begins to grow and emerge from the seed.  The plant grows into a sapling (shown right) and then into an adult tree which is also known as the sporophyte.  In order to produce spores or eggs, specific cells in the tree undergo meiosis.  Those spores are then transported while the eggs are kept in the ovary.  That completes the cycle and then the whole process begins all over again. 

    The Macadamia tetraphylla flowers in the months of August to September.  In addition, it produces its fruit from March to April.  This species has a juvenile period of about six years.  This means that the plant does not fruit for the first 6 years of its life (shown left is first fruiting of a plant).  In addition, they reach maturity around ten years of age.  Macadamia tetraphylla is used as a commercial crop for about 40-50 years of its fruiting life time.  They can, however, fruit for up to 100 years!



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