The Dilleniidae
Family Overview - The Salicales
Salicaceae - the Willow Family

Diversity:  Only three genera, with willows (Salix - ca. 400 species) and poplars (Populus - ca. 35 species) in the North American flora but, as was the case with taxa of the Hamamelidae, the relatively small number of species includes many with a wide distribution and, as a result, plants of the family - all woody (shrubs or trees) are conspicuous elements of a given flora and frequently encountered.

Distribution:  Throughout temperate parts of the World with maximum diversity toward the north and a strong ecological preference toward habitats associated with water.  In our local flora, taxa of both genera will be found beside ponds and along streams and rivers.  The Texas flora includes 17 species and 6 infraspecific taxa.

Floral structure:

Significant features:  Floral structure of the Salicaceae is an expression of extreme reduction.  The pistillate flower is represented by only a single, compound pistil and the staminate flower is, in Salix species, just two stamens.  These imperfect flowers are produced in catkins and most species of the family are dioecious.  While the reproductive adaptive syndrome of the Salicaceae mimics that of the Hamamelidae, there is general agreement that this similarity is not based on common ancestry and most classification systems place this family in a position well removed from families of the Hamamelidae.  This points out the importance of the gynoecium in that the primary structural difference between this family and the other 'amentiferous' flowering plants is the capsular fruit.  As indicated by the local name for our most common poplar - 'cottonwood' - seeds emerging from capsules of the Salicaceae are comose (with a tuft of trichomes) and, as a result, all reproductive events - pollination, fertilization and dispersal of the product - are wind-mediated in this family.

 The single representative of Salix in our local flora - S. nigra:

Staminate catkin at anthesis Pistillate catkin at anthesis Pistillate catkin with fruit and comose seeds


kohler pop
Staminate catkin of Salix with dark bract subtending each flower Populus nigra - overview -  from Kohler's Medicinal Plants


The aspen (Populus tremuloides) is a rhizomatous woody perennial.  A single plant can therefore produce many shoots and a 'stand' of aspen often represents a single plant.  The relatively recent capability to employ molecular markers to identify individuals has allowed large 'clones' to be defined and, given the growth rate for this plants, some of the larger aspen clones might be the oldest living individuals.

More information on the Salicaceae

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