Evil holly trees were a class of Evil Tree encountered in the Land of Holly and Hawthorn, in the holly area surrounded by holly trees that couldn't be interacted with in any way. They appeared during the Holly and HawthornEaster Event. They were slain like normal evil trees, but with no firemaking or woodcutting requirement, and with no experience gained. Their slaying also contributed to the balance of the seasons with the Land of Holly and Hawthorn, and the appearance of the Season Tree.
If you searched a fallen evil holly tree with the fake year in your inventory, a chat box message appears, stating "You must help to fell an evil holly tree before you can claim rewards." This would be shown even if the player has contributed to killing it, causing some confusion. This is most likely a glitch.
Evil holly trees could be struck by lightning if it stands for too long, just like normal evil trees, and players would still be able to receive the fake year as long as they contributed to killing it.