The Canopy Song

Restore an old harmonic measurement at the Highroot canopy.

Requirements

Find the bard at Highroot Bank
The bard reads the forager's note and nods slowly. 'The canopy song was a measurement. Sing it true and the canopy answers in time. If it doesn't, something below is pulling on it. Help me set it up again.'
Gather canopy specimens at the grove
You pick six leaves from six heights, the way the bard's notes ask for. Two of them are the wrong colour underneath. She'll want to see that.
Set up the harmonic at the court
The bard tunes three pipes to the leaves and sings the old line. The canopy answers a full beat late. 'That's the wrong answer. The roots aren't keeping time.'
Re-measure under the western canopy
Same lag here. Worse, even. The bard marks it in her notes with a small dry sound. 'Whatever's wrong runs under the whole grove. We need to talk to the ents at Stillbark.'
Bring the notes back to the bank
The bard seals the new measurements in a tube. 'The ents won't speak to strangers. Take these to their council at Stillbark and don't rush them. They keep their own time.'