Sweet Chestnut (Castanea sativa) catkins. Two types of flowers are produced. First are a great number of staminate catkins (male only) which are followed by a smaller number if bisexual catkins which are found at the apical part of the annual branch. The female flowers are found at the base of the bisexual catkins. The pale yellow catkins are the male catkins. The colouration is due to the numerous stamens and the pollen that they carry. Bisexual catkins can be seen low on the right. On these catkins, a small number of female flowers can be seen but the male flowers have not yet opened. The abundant production of pollen suggest that this species is anemophilous (wind pollinated). However, the flowers are scented and the pollen is heavy and sticky, which is typical of entomophilous plants (insect pollinated). Research suggests that insects do indeed play a significant role in pollination.