Zhongtou is one of the more ornamental leaf variegation types in orchid line-art variegation
Zhongtou is one of the variegation patterns in the leaf line-art variegation of Chinese orchids (guolan). It refers to a leaf whose central area shows a large expanse of white, yellow or creamy white, while the leaf margin retains a ring of green edging; overall the leaf center looks translucent and bright while the edge stays green, creating a very striking contrast. Because the translucent part runs through the main body of the leaf, it has traditionally been regarded as one of the higher-grade ornamental categories among line-art variegations.
In appreciation practice, zhongtou is often mentioned alongside concepts such as zhongban (central blotch), gao yi (striped variegation), fulun (rim variegation) and bian yi (edge variegation). In zhongban the blotches are scattered across the middle of the leaf and generally do not reach the leaf margin; gao yi appears as longitudinal lines; fulun and bian yi only edge the leaf margin; whereas in zhongtou the translucent area occupies the main body of the leaf with a complete green edge. Once these differences are grasped, it is not difficult to tell them apart. Zhongtou variegation can appear in many orchid species, such as Chunlan (Cymbidium goeringii), Lianbanlan (Cymbidium tortisepalum var. longibracteatum), Jianlan (Cymbidium ensifolium) and Molan (Cymbidium sinense), and its expression and stability differ somewhat from species to species.
Caring for zhongtou variegated plants takes more care than for ordinary green-leaved orchids. The translucent parts contain less chlorophyll, so strong direct sunlight should be avoided; it is best placed in a bright, diffused-light environment, otherwise tip burn or sunscald spots easily occur. In daily care, nitrogen fertilizer can be appropriately limited, attention should be paid to ventilation and the air permeability of the potting medium, and watering should follow the principle of watering when dry and letting it dry between waterings, to avoid long-term excessive moisture causing root rot.
It should be noted that variegation patterns are not fixed; light, temperature, fertilizer and water, and the plant's growth vigor can all cause the degree of zhongtou to advance or recede. The variegation of new shoots is sometimes brighter or paler than that of old shoots, which is a normal phenomenon. When selecting, plants whose translucent parts are clean, whose green edge is clear, and whose leaves are thick and glossy are preferable; combined with a sturdy plant shape, their ornamental value is higher.
