I have had to keep the Zucchini trimmed back some to keep it in the 4 by 4 foot space I've given it and the squash got planted later but is also starting to fill it's 4 by 4 space. When I first started seeing flowers I knew that they were either male female but I couldn't tell until which until I finally noticed a female flower. On the inside there are five little fingers like the one below.
To pollinate your flowers take a small soft paint brush to the center of the male flower and then lightly dust the pollen into the center of the female flower.
So far these plants are doing amazingly well and they are huge and beautiful! Not to mention the Zucchini is delicious;)