Really interesting subject, hop rhizomes actually travel laterally, the reason they do this is they are looking for a host plant (tree) something for the bines to climb up. The root is split into sections the root cap is the tip of the root which senses the environment and protects the root, next is the Meristem this is region where the cells rapidly divide elongate and bend next is the transition zone which is electrically active and is thought to be the nerve centre of the plant and where the oxygen is used and what some believe is the brain of the plant.
Darwin was the first to suggest plant had a brain in the root, and they know the difference between movement from the wind or something touching it, the hops first cousin is notorious for this, touch one plant and they all start to give off a scent I suppose its something like a pheromone that's why they have extractor fans in a grow room.
And I wish I could stop referring to cones as buds.