My best friend is getting married in August. I am in her wedding and making the cupcakes as well. She sent me this picture of what she wanted from the knot... exactly what tip should i use to make these? Thanks for your help!

This, I beleive is the rose making tip. Sorry, Im horrible with the numbers. But I used to make daisys this way.
What you do is angle the largest side of the rose tip down on the cupcake and pull it in to the center. You can kinda have the tip to an angle also to create a petal with some dimension. Very easy to do! HTH

It's probably a #101 or a #102 petal tip for teh petals and a #18 star tip for the center.. personally I think a round tip might look a little more finished for the center, but if she is set on these it's a star tip. HTH's

Yup, they'll be a bit of work. But I agree with jkalman on it being a 101 or 102. Here are the instructions using the 104:

http://www.wilton.com/decorating/basic/daisy.cfm

You can see the petals are a little bit bigger using that tip. The opening of the tip will be nearly parallel to the surface of the cupcake: the wide end will touch the cake, the narrow end will be just slightly above the surface. Just drag from outer edge of cupcake towards the center. GL.