From low elevation streams to alpine meadows some form of Willow abounds in the Four Corners region.  But many Willows, especially the shrub Willows, are difficult and very time-consuming to identify.  Here is what William Weber has to say about Willows in his Colorado Flora: Western Slope

Willows are difficult to identify because the important characters are ephemeral.  One needs to know young leaves, mature leaves, flowering and fruiting catkins, and stipules.  These parts appear, mature, and fall at different times of the year; in order to see them all one must tag a bush or tree and return to it through a season.  Twig color and plant height are also important.  Most of us do not have enough patience....  Anyone living near Willow stands and in search of a productive hobby would do well to study them.  They actually are easy to know if the species are seen in all seasons.

Intermountain Flora states it this way:

The notorious difficulty of identifying specimens of Salix arises from several sources.  Staminate flowers, pistillate flowers, fruits, and leaves all provide useful taxonomic characters, but these are frequently not all available at the same time....  Vegetative characters are frequently plastic.  Leaves of vigorous young shoots are not only unusually large, but they tend to have disproportionately large stipules.  A number of species that usually have entire leaves sometimes have the leaves toothed, and vice versa....   Several species that usually have pubescent ovaries sometimes have the ovaries glabrous....  Finally, the specific limits are frequently blurred by hybridization, sometimes between species that do not appear to be very closely related.

Following are some of the observations one needs to make in order to identify Willows: 

1) Does the plant flower before the development of leaves, at the same time, or after? 
2) Are the seed capsules glabrous or hairy?
3) What is the leaf color and what is the shape of the leaf and margin?
4) Are the twigs and branchlets glaucous, hairy, glabrous?
5) What is the shape, size, and duration of the stipules?
6) What are the dimensions of the catkins?

Unfortunately, even if one makes notes about the above characteristics, one still should be quite careful in identifying Willows because there often is a wide range of variation in plant characteristics.  For instance, leaves of a particular species might be hairless, oval, blunt-tipped, and smooth-margined or hairy, long and narrow, pointed at the tip, and serrated. 

As Weber indicates above, it is best first to learn those Willows closest to home, i.e., those Willows one sees and can study most often.  Then one can pick other Willows which have unusual characteristics, such as the drier land growth habitat preference of Salix scouleriana.  One has the best chance of keying species in the spring.

The botanical key that you use to identify Willows can also make quite a difference in your ability to arrive at a satisfying answer.  Some botanical keys, such as Weber's Colorado Flora, are all inclusive, i.e., one must look at the Salix species for numerous characteristics at the same time.  But if those characteristics are not present when one is attempting to key, one is just not able to identify the plant.  Other botanical keys, such as Welsh's A Utah Flora and Cronquist's Intermountain Flora, provide three separate keys: a key to Salix when male flowers are present, a key when female flowers are present, and a key when no flowers are present, i.e. a vegetative key. (Click for a vegetative key.)

Birds and deer donít seem to mind the identification problems; they use Willows for nesting sites and browse without ever knowing the exact species.  

Native Americans utilize Willows (and Aromatic Sumac, Rhus aromatica) in basket making. 

And, of course, Willows are often planted as ornamentals throughout the Four Corners region, the United States, and in many other parts of the world.

The genus, Salix, was named by Linnaeus in 1753.  "Salix" is the classical Latin name for "Willow".

This is a native species.

Salix scouleriana
Salix scouleriana (Scouler's Willow)
Salicaceae (Willow Family)

Montane. Woodlands.  Summer. La Plata Canyon, June 22, 2010.

Salix scouleriana grows to about twenty feet tall and can have stems to 5, 10, or even 15 inches in diameter. But thickets of much smaller plants (as shown in the photographs) are the norm.

Weber indicates  that Salix scouleriana is the only Willow in the Four Corners area growing in forest areas away from wetlands on what Intermountain Flora calls "well drained open slopes... from the foothills to middle or occasionally fairly high elevation in the mountains.... This is the only Intermountain Willow that could be considered an upland Willow growing on drier sites." Welsh's A Utah Flora agrees that the plant can grow on well-drained slopes but indicates that it also grows in wetlands.

John Scouler (botanist, physician, professor) discovered this species for science (probably in 1824-1825) near the Columbia River. Joseph Barratt named the species and William Hooker described it in 1839.

(Click for more biographical information about Scouler.)

Salix scouleriana

Salix scouleriana (Scouler's Willow)
Salicaceae (Willow Family)

Montane. Woodlands.  Summer. La Plata Canyon, June 22, 2010.

Leaf blade shape and hairiness vary widely from plant to plant and with the age of the leaves on individual plants.

Salix scouleriana

Salix scouleriana (Scouler's Willow)
Salicaceae (Willow Family)

Montane. Woodlands.  Summer. La Plata Canyon, June 22, 2010.

Female flowers (and young branches) are softly hairy.

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Questionable presence

Salix scouleriana

Range map for Salix scouleriana