This reminds me ofa combination of the Asterix book 'Mansions of the Gods' (with the magically-treated acorns that grow into trees in seconds) and a high-level Druid spell from D&D that makes acorns into hand grenades...
(
Tribs 🦇 ↓ dn ʎɐʍ sᴉɥʇ ↓🦇,
Thu 11 Feb 2010, 21:00,
archived)