This miniature ecosystem has been thriving in an almost completely isolated state for more than forty years. It has been watered just once in that time.
The original single spiderwort plant has grown and multiplied, putting out seedlings. As it has access to light, it continues to photosynthesize. The water builds up on the inside of the bottle and then rains back down on the plants in a miniature version of the water cycle. As leaves die, they fall off and rot at the bottom producing the carbon dioxide and nutrients required for more plants to grow.