The order is generally placed in a position near the Flacourtiaceae, the basal family in the Violales. The compound salicin, which is common in the Salicaceae, is also found in Idesia and some other flacourt genera. While wood and pollen feature support this relationship, seed morphology points more towards the Tamaricales. By 1926 Engler himself admitted that the flowers of Salicaceae are reduced rather than primitively simple, but he put forward the curious argument that the great floral reduction of the family indicates its great age and therefore supports its assignment to a position as the beginning of the taxonomic sequence. Such a view makes hash of efforts to integrate phylogenetic thinking into taxonomy.
All modern groups are of the same age, if their remote ancestors are taken into account.
Differing ages can be assigned only by considering the time when the essential features of the modern group were acquired. A phylogenetic arrangement properly takes as basal those taxa that are least modified from the common ancestral type, instead of starting with those that are most modified. 2 or 3 genera and perhaps as many as 400 species. Arctic and temperate regions especially in the Northern Hemisphere but also in southern South America, southern Africa and portions of southern Asia. The Salicaceae various greatly in habit.