Plants are monoecious (rarely dioecious). The plants are dioecious, rarely monoecious. The flowers are unisexual, some species are monoecious, others dioecious. They have usually unisexual flowers and can be both monoecious or dioecious. The plants can be monoecious or dioecious. They may be monoecious or dioecious. The trees can be monoecious or dioecious. Species are characterized as monoecious or dioecious based on their gonophores. They can be either monoecious or dioecious. Most conifers are monoecious, but some are subdioecious or dioecious; all are wind-pollinated. It is unclear whether glossopterids were monoecious or dioecious. Notably, there is no clear split between dioecious and monoecious lineages. Maple species, such as "Acer rubrum", may be monoecious, dioecious or polygamodioecious. These plants are functionally dioecious, flowers imperfectly unisexual. Subdioecy (the occurrence of monoecious individuals and dioecious individuals within the same population) is widespread.