The figure above illustrates how compound leaves could be derived from a simple tree fern-like leaf. Stangeria, Bowenia, and the multipinnate forms of Cycas have been added to show how cycads continue to adapt, developing more efficient leaf designs. Not shown are species such as Macrozamia stenomera, M. diplomera, and the relatively recently discovered genus Chigua that also have developed multipinnate leaves. Such a leaf architecture increases the amount of photosynthetic surface of a leaf, while keeping wind- loading to a minimum. The potential for serious structural damage by insects would also be reduced. Since cycads produce new leaves no more than once or twice a year on average, they need to protect such a major metabolic investment from damage.