Been thinking a bit about taproots as a good model for stubborn ideas.
Most plants start with a taproot, which is one main root forming from the enlarging radical of the seed. The tap root can be persistent through out the life of the plant but is most often replaced later in the plants development by a fibrous root system.A persistent taproot system forms when the radical keeps growing and smaller lateral roots form along the taproot; often the radical dies some after seed germination causing the development of a fibrous root system which lacks one main downward growing root. Most trees begin life with a taproot, but after one to a few years the main root system changes to a wide-spreading fibrous root system with mainly horizontal growing surface roots and only a few vertical, deep anchoring roots. A typical mature tree 30–50 m tall has a root system that extends horizontally in all directions as far as the tree is tall or more, but well over 95% of the roots are in the top 50 cm depth of soil.
– thanks wikipedia