It could be hope.

When its leaves turn brown.

It's a sign that it might die, anytime soon. Either that or that it's clinging on to whatever it has just to try to keep surviving. It could be due to too much sun, and drying, or that it didn't get the food and water it required. Or maybe the coke you poured in yesterday wasn't too good for its growth. Either way, it's a sign.

A sign that it's losing something important. That something in it has already died.