They grow fruit using their magical energy, but there is usually no one to eat them. They were meant for the race residing in the holy lands (dryads), but the immortal race just had them accumulate. Moreover, the fruit being magical, does not rot no matter how much time passes. This fruit is sold as a rare ingredient in human markets. It’s really hard to find and can be sold for a large amount of money. The reason for the price is its abundant magical energy. Just one drop can keep you going for seven days. Without feeling hunger. Another reason for the high price is the fact that treants don’t interact with other races, and the troublesome dryads, who manage this product, give it out sometimes as a present.