Female flowers have the little fruit which will turn into a big fruit behind the flower. The male flowers have just a plain stalk coming up to the back of the flower. Inside the flower, the male has a sticky up thingy (as you might expect

) which is yellow and will be covered in pollen. The female flower has another slightly different yellow sticky up thingy (you can tell I didn't do botany at school

) which is divided into about 3 parts I think, which doesn't have any pollen on until it is fertilised. Each female flower is open for only a day, in fact so are the male flowers, so if they are not pollinated then that flower will go brown and drop off, but lots more will form.