The Clinging-to-rock "Ishizuki" style of bonsai trees is one of the most challenging and rewarding forms of the art. It involves growing a tree on a rock, or embedding its roots into the crevices of a rock, so that it appears to be clinging to it for survival. The rock provides a contrast to the foliage and adds a sense of drama and realism to the composition. The tree must be carefully selected and trained to match the shape and texture of the rock, and the rock must be stable and porous enough to allow the roots to penetrate and absorb water and nutrients. The Clinging-to-rock style requires skill, patience and creativity, but the result can be a stunning display of harmony between nature and human intervention.