he remembered her stories of the dark temples , of vigils kept , of days wandering the cliff paths looking for a rare herb , that could be picked only at the waning of the moon ; she used to sing him asleep with the qualities of the plants , and he could still remember the names - ratbane , the monarch , butterfly , cloudflower , fox-ivy , chalk-holly , silver-feather , thousand-leaf , augur 's staff - though he could n't recognise a single plant , and had forgotten , if he had ever known , what they were good for .