Avocado trees can be tall or spreading, and they have elliptic to egg-shaped leaves that are 10–30 cm (4–12 inches) in length. The small greenish flowers are borne in dense inflorescences and lack true petals. The flowers have nine stamens, arranged in three series, and a one-celled ovary. Interestingly, there are two types of avocado flowers, A and B, depending on the cultivar. These flowers are dichogamous (male and female parts mature separately), and each flower opens only twice. Type A flowers are functionally female in the morning, close at midday, and then reopen as functionally male in the afternoon of the following day. Type B flowers are functionally female in the afternoon, close in the evening, and then reopen the following morning as functionally male. When the two flower types are grown together, this temporal overlap of mature male and female parts encourages cross-pollination and, thus, greater fruit production.