a screenshot with the text "cherry blossoms get their color from anthocyanins, so do hydrangeas. a higher pH results in a more red/pink color, and a neutral pH affects the color much less. limestone can naturally keep water in a roughly 6.5-8.5 range. 7 is completely neutral. less sunlight, and warmer weather can cause cherry blossoms to be more dully colored as well. so we assume the water is lined with limestone, keeping the pH neutral-high. There is little sunlight in the cave-thing, and it traps heat well. therefore the flowers are less pigmented, and so is their dryad after staying here."
a screenshot of a web browser with several tabs open, all about cherry blossoms, flower coloration, or limestone. The displayed page is the wikipedia page for anthocyanins - specifically the pH subsection
not to spoil one of the puzzles but... god forbid I just say 'the dryad is magic, don't worry about it' no no I just *had* to spend an hour researching the coloration of cherry blossoms and how to affect them.
speculative biology my beloved <3