selective weed killer needed

Hi Miken, if the leaves and flowers are on the same plant then no. If you are trying to get rid of the leaves of plant A and not damaged the flowers of plant B yes it is possible by putting a little Roundup in a bowl, putting on a latex glove, dipping the gloved fingers into the bowl, rubbing fingers together to remove almost all the liquid, then (very carefully) just rubbing the leaves between your fingers - making sure you do not touch or allow the Roundup to touch the flowers.

Roundup (Glyphosate) will kill only the plant to which it is applied, but you need to find a way to get it on the leaves of the weed without it going on the the garden plant. I have in the past mixed it with thin wall paper paste (non-fungicide one, if you can still get it). You then paint the leaves with the solution and it sticks without dripping. This is a very laborious task though and only worth doing for a particularly precious plant.

Do as Owdboggy says, mix selective weedkiller with paste, made up with flour and warm water. Paste on both sides of the leaves with an artists brush.

What i've done before with bindweed close to a wanted climber is paint on Tumbleweed (another glysophate based weedkiller, but in a pot with brush) then cover the painted foliage with a plastic bag doing up with a rubber band or similar. Remove once weed is wilted. It's unsightly but at least it's only temporary and no danger to other plants.