On IRC: Freenode server
http://webchat.freenode.net/Join the #planeshift-contributors channel.
Talk to Botanic or I, we have plenty of things that we need help on (especially me, at the moment). I think if you were specific that you only wanted to draw flowers, that may be why you were turned down. If you branch out and tackle projects that are in the areas we need help, then you'll succeed.
On further note: I was turned down at first when I applied, but when the team saw that I could knuckle down and do some work, they reconsidered. Sometimes you just have to wait, and contributing while you wait will get your name recognised.