Fertilization

Fertilization a pollen tube grows down the style carrying the male gametes to fertilize the ovule inside the ovary  the fertilized ovule develops into a seed and the ovary develops into a fruit

stamen male part

so it can catch grains of pollen

When a seed germinates, a young plant is formed that grows roots, stems and leaves called vegetative structures  This vegetative phase last until a trigger causes the plant to switch into its reproductive phase and produce flowers  This happens because the meristems in the shoot start to produce parts of flowers instead of leaves.  The main trigger is the day length/dark period (although temperature can also play a role)

Parts of the Flowering Plant  The flowers are the structures that allow for sexual reproduction in plants.  male gametophytes (the pollen grains) are produced on the stamen (the male part of the flower)  stamens consist of a thin stalk called a filament and an anther, where the pollen grains are formed  female gametophyte is found within the pistil, the female part of the flower  the pistil consists of three parts; the stigma, style and ovary.  the style is the stalk connecting to the ovary, the stigma is the sticky part at the tip of the style, and the ovary is where the egg cells are kept

Mutualism an association between two organisms where both organisms benefit. ex Pollinators gain food from the nectar and plant gains a way to transfer its pollen to another plant

in long-day plants, the active form of the pigment phytochrome leads to transcription of the flowering time gene (called FT gene). The mRNA transcript of this gene then flows through the phloem to the shoot apical meristem where it gets translated into the FT protein, which leads to the activation of flowering genes to transform the leaf- producing apical meristem into a reproductive meristem.

 seeds often travel long distances from the parent plant to help reduce competition and spread the species  dry and explosive (e.g. milkweed)  fleshy and attractive for animals to eat (e.g. berries)  feathery or winged to catch the wind (e.g. maple trees)  hooked to cling to animals coats (e.g. burrs)

Photoperiodism Only the active form of phytochrome (P fr ) can cause flowering, however its action differs in certain types of plants  Plants can be classed as short-day or long-day plants – the critical factor in determiningtheir activity isnight length Short-day plants require the nights to reach a critical length to flower.  In short-day plants,P fr inhibitsflowering and hence flowering requires low levels ofP fr (i.e. resulting from long nights) Long-day plants require the nights to be less than a critical length to flower.  In long-day plants,P fr activatesflowering and hence flowering requires high levels ofP fr (i.e. resulting from short nights)