In this close up photo we can see how the orchid roots love to grow along and cling to the tree bark. Other than terrestrial orchids, this is how orchids grow. Growing in a pot must seem strange to the plant in comparison. This particular tree, with its craggy bark, is a classic spot for a happy orchid. We can see how the roots follow the uneven surface, finding support and water among the crevices. Orchid roots grown in a pot are round but mounted they flatten to grasp the mount.
The classic mount for orchids is cork which is available in plaques of varying sizes. Some orchids, particularly those with thin roots such as Oncidium are fond of tree fern mounts and we see their roots growing all the way through them. A branch from a tree that has been trimmed can make a good mount; we really like to set an orchid in the crook of a branch when possible. Wood slat plaques look something like the flat bottom of a vanda basket and can be used either as a vertical or horizontal mounts.