The purple bubble tree (now driven to extinction) got pushed out of the Huggs Temperate Forest due to all the broad-leaved plents. To cope with this, it evolved into the bubble arch. It can survive in poor soil and high winds. It developed an arch to keep it stable in those high winds. The bubble tree was already small, but, in fact, it grew a bit to get as much sunlight it can from its trunk. It still has tiny leaves around the bubble seeds, but they are tiny. Any desperate herbivore will still have to deal with its exploding hydrogen seeds. It can kill its own nibbling herbivore prey. It uses the burnt carcass as fertilizer to help in growth, thus enriching the poor rocky soil. It is completely fire retardant now to deal with wildfires in the rocky cliffs. Many other plants will catch on fire during the summer, but the bubble arch will stay virtually unaffected, only loosing its seeds, which quickly grow back. This actually clears away the annoying stickyballs in the area, thus giving the other plants a chance to grow.