My friend Anne W made a special trip to my house to deliver some rhubarb leaves as she knew I was interested in trying them for dyeing.
India Flint in her book Eco Colour says rhubarb leaves are both a mordant (oxalic acid) and a source of yellow.
I took a piece of fine wool cloth , wet it, and laid onto it some casuarina leaves and some rosemary stalks, then the rhubarb leaves and then more casuarina and rosemary leaves. I folded the fabric on itself and rolled it firmly then bound it tightly with string. I then placed it in an aluminium pot with water and additional rhubarb leaves. There was some residual cochineal colour in the pot left over from a previous dyeing session. Despite several washings of the pot some of the cochineal had remained. I could see it but didn’t expect it to manifest itself in the new bundles of cloth.
I brought the pot to the boil and simmered it for one hour. It was then cooled overnight and unwrapped in the middle of the next morning.
Here are images of the result after washing in Lux Flakes, drying in the shade, and ironing.

Lightweight wool, casuarina leaves, rosemary bunches and rhubarb, simmered in rhubarb and water , in the presence off some small amounts of cochineal.
Next I want to try a similar dyeing exercise using casuarina leaves pre-soaked in iron water to see if I can maintain the gold but get more defined and darker casuarina markings.
Gorgeous!