I had a little play yesterday with transfer inks. They work on polyester fabrics, also on a polyester mix but less well - it absorbs less of the ink. It works so well on Evolon (a woven polyester fabric) which is the heart labelled number 2. I also used the Evolon with the plant material.
Basically you paint the inks onto copy paper then iron it onto fabric so you can paint solid colour or paint a design onto the paper or cut shapes out of the painted paper. With the plant material you place it onto the fabric, put the painted paper on top then iron over it. Also transferred some of the ink to organza ribbon shown at the bottom here.
I've also made some organza flowers, one made using a tea-light to shrivel the edges of the organza and the other 2 using a heatgun.