Ecoprints on Paper

I'm working on a sketchbook for the Art House Sketchbook Project, and I did some ecoprints on paper. It's a 4" x 6" watercolor sketchbook, and the leaves print beautifully on watercolor paper. I get more yellows on the paper than I do on cotton or linen fabric, and I'm wondering why. Could it be the acid content of the paper or something?

This first one is mulberry leaves:



I don't know what type of tree these leaves are from. I'm going to have to look it up.



This is eucalyptus:



Rose-scented geranium:



And Liquid Amber, a type of maple tree:

New Ecoprints

Here are some new ecoprints that I unwrapped the other day. I don't know what kind of tree these first leaves were from, but they sure print well.



This one is fallen leaves from a Mulberry tree.



And this is fallen leaves from the Evergreen Pear trees in my backyard.



All on linen.