Stretch the stained fabric over a bucket. Sprinkle with bicarbonate of soda, be generous. Finally, wet stain by sprinkling with white vinegar, just enough for the bicarb to bubble. Leave in sun for about 4 hours...This worked a cinch, after I read that having washed the fabric, it would be impossible to remove the stain, I was frantic, as this was one of my husband's favourite white cambric shirts, of which he had stained the entire front while carrying an arrangement with yellow tiger lilies.
Another good tip to prevent pollen disasters is the moment your floral arrangement is in the vase, get some tissue and scissors and snip off the bits of pollen into the tissue and toss in the bin - you can avoid the nasty stuff altogether.
Don't go near it with water! Gently blow off any pollen, then roll some sticky tape around your fingers, and use the tape to dab off the pollen. Keep rotating the tape and dabbing until it all comes away.
Similar to sticky tape, and works first time, every time...bread. Just rub the pollen with any type of fresh bread and the pollen disappears! Then all you have to do is clear up the crumbs!