The other day, I found a new plant that looks similar to my favourite wild fruit, Sand Apples or Dwarf Mobola Plums and when I found out what it was, I was fascinated to learn that these plants are called geoxyles and they are in fact underground trees.
Pygmaeothamnus zeyheri are also called Sand Apples but in another local language, they are referred to as "goorappels" - the word "goor" means "nauseating" and although these are not poisonous, they aren't edible either. When you find these types of plants in the wild, they generally occur in fairly large patches, like the Mobola Plums below, and I always thought that the patches were just systems of underground stems.
What I didn't know is that there is in fact an entire tree underground and what makes these trees particularly fascinating is that it is another adaptation to fire that is found in plants that live in grasslands. Although the rainfall in the area is actually high enough to support a forest, it is a grassland and the trees are living underground! Fires happen in winter, during the dry season and the only trees that survive are those with fireproof bark or those that live in among the rocks but there is yet a third way. Trees have gone underground and grass fires only burn their dry leaves in winter, allowing them to sprout again once summer comes. I always thought it odd that fruit similar to what you'd find on a tree grows close to the ground and now I know why.