I picked a light green specimen from a fenceline and used a light green filter (+ 1/2 stop) to increase contrast and separate its values from the rest. N+ development helped bringing out the texture.
Thanks for your comments ! I have a cropped version of this image, but I don't like it as much as the full negative. While the lower two thirds are the richest part, without the top it loses context, or ar least that is my impression, since I remember the plant in its surroundings.@Michael: I try to compose all my images full viewfinder/groundglass. I guess its a bad habit when you don't have an enlarger.