If you move your cursor over the parasite you'll see you can attack it, click on it and some monsters will appear, kill them, then click on the parasite again. Some of the nuts make paths through the tree, but you probably already know that, and some are like healing potions (I think).
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Goddess of Undress
Co-owner of the Evil Petting Zoo and Sorceress of the HADB
OLD COOTS eye candy and Disrobed Division of the ORT
And her sidekick Pink