These seeds only germinate in very wet climates and grow into huge trees which branch out and link to other trees. In this way all the trees share their nutrients with each other and all of them can grow taller faster. Their rate of growth increases at an exponential rate throughout their lifespans until they eventually die, leaving behind seeds that are a great and rare delicacy. They would be very rare indeed if it wasn't for the fact that torrent leeches always collect and hoard them as an important source of food and so the seeds can always be found somewhere. Not edible to heroes.