That is Cleome also known as spider plant or cats whiskers. It is an annual, easy to grow from seed, will reseed itself the following year. The seedpods are forming below the flower--the long green things, when they turn brown the seeds are mature and can be collected.
Wow, you did that very fast. Thank you so much! It's growing like an alien plant! I was beginning to fear that it would eat someone! :-)! And you're right. It's easy to grow if I grew it. It's got so many new growths already. Can I cut this down or something? And a friend wants to have a piece of this? Can he cut it somewhere to grow or does he have to wait until it's seeds turn brown. Bear in mind that our summers last until October/November.
Tip: Be sure the seed pods are fully ripe (brown) but not opened yet to save the seeds. Cut them off the stem carefully, perhaps holding an envelope underneath as the pods may rupture. I save mine in a paper envelope to make sure they fully dry and do not mold. My cleome didn't re-seed, but I am in Zone 6; thankfully, I saved seeds last year!