THE POPLAR / WILLOW FAMILY (Salicaceae)

This is a family of woody shrubs or trees with both deciduous and evergreen species that may build clones via underground runners and rhizomes. As so often, phylogenetic studies have recently resulted in an expansion of the ‘membership’ which confuses the picture and makes description of characteristics difficult.

The young and older leaves of some Salicaceae differ in form (heterophylly). Most have leaf stems (pedicels) and are arranged alternately and spirally on the stem, occasionally oppositely. In most original members of the family each plant is either male or female, carrying only one single-sex type of flower. Both are found in spike-like clusters, either hanging (catkins) or upright. (This is not typical of the newcomers to the family however). The willow catkins, both male and female, posess nectaries and are insect pollinated whereas the poplars do not and are wind pollinated and flowering in this case usually occurs before the leaves develop in spring (early flowering).

(source: Wikipedia)