CUPULIFERAE  , a botanical

order, or, in recent arrangements, group of orders, containing several familiar trees . The plants are trees or shrubs with simple leaves alternately arranged and small unisexual flowers generally arranged in catkins and pollinated by wind-agency . The generally one-seeded nut-like fruit is associated with the persistent often hardened or greatly enlarged bracts forming the so-called cupule which gives the name to the group . The group is subdivided as follows, and these subdivisions are now generally regarded either as distinct natural orders or the first two as sub-orders of one natural order . Betuleae or Betulaceae . Female flowers arranged, two to three together on scale-like structures formed by the union of bracts, in catkins; ovary two-celled; fruit small, flattened, protected between the ripened scales of the catkin . Includes Betula (birch) and Alnus (alder) . Coryleae or Corylaceae . Female flowers in pairs, the bracts enlarging in the fruit to form a membranous cup (hazel), or a flat three-lobed structure (hornbeam) . Ovary two-celled . Includes Corylus (hazel) and Car pinus (hornbeam) . Fagaceae (Cupuliferae in a restricted sense) .

Bracts forming a fleshy or hard cupule which envelops the one to several fruits . Ovary three-celled . Includes Quercus (

oak), Fagus (beech), Castanea (sweet-chestnut) . Detailed accounts of the trees will be found under separate headings .