Some species, including the sycamore, are far more susceptible than others to malformations. Likewise, fasciation is also common in the sycamore, including fasciation of branches, twigs, petioles, inflorescences, and flowers. Young sycamores have short and long shoots, while mature trees have only short shoots. At its widest, the fasciation is about 5cm wide and curved, and usually branches into several shoots. At this point the arrangement of leaves, buds and twigs does not show any distinct pattern, but by looking at the longest shoots it is possible to see a change in the position and the number of leaves and buds along the length of the stem.
Buds occur at the base of the leaf petiole and, like the leaves, normally occur in whorls of two.
In sycamore it appears that the increase in the number of parts eventually leads to the production of fasciation. This suggest that there is a lack of hormonal control in the growing point and, as the trait appears to be more come in some areas than other, that the environment strongly affects its expression. More recent work on the causes of fasciation include Albertsen et al . Genetic Fasciation Fasciation of the stems of the 'mummy pea' was one of the original seven Mendelian pairs of characters. This character is often controlled in plants by a single recessive gene, but inheritance can also be non-Mendelian.