Distinguishing Salix caroliniana from Salix nigra

This simple post is for distinguishing Salix caroliniana from Salix nigra, whose ranges overlap and, indeed, can be found growing in the same pond or along the same stream.

Why do we care about these two species?  Both are excellent re-vegetation species for anywhere with copious moisture, but the Salix caroliniana is more useful and suitable for backyard, detention basin, and other moist soil applications where the size of Salix nigra would prove unsuitable or unwelcome.

Salix caroliniana

Salix caroliniana is described as a small tree, but most often grows as a nice multi-stemmed shrub along the margins of ponds, streams, and lakes.  There seem to be three separate major populations; one centered in Missouri and Arkansas, one along southeastern coastal US, and a disjunct population scattered along the Appalachians in VA, WV, and PA; other populations are apparent from the map below. The most isolated population, in Erie County PA, might still exist; Salix caroliniana is considered endangered in Pennsylvania.

Salix nigra

Salix nigra is a far more common and ubiquitous species across its range and most always grows into a tall tree even it starts its life as a few-trunked shrub.

Distinguishing Salix caroliniana from Salix nigra

There are three fairly obvious distinguishing features between these two species.  Salix caroliniana and Salix nigra can hybridize and produce offspring showing characteristics of both species, so this post is not a definitive guide.

Salix caroliniana has reddish twigs and roundish microphyllus leaves along the stem

Note the distinctive reddish color of the branch tips and the small, roundish bract-like leaves growing at the base of the main leaves in the image below.  Click any image for a larger view.

Salix caroliniana leaves have whiter undersides and slightly more minute hairs than Salix nigra

Granted, these differences are likely highly variable in the field and unless observable side-by-side, will be hard to distinguish one from another.

Salix caroliniana is more of a multi-stemmed shrub than Salix nigra

The picture below shows the typically-found growth habit of Salix caroliniana.  Actually this picture shows both Salix caroliniana and Salix nigra; the caroliniana is on the left and the nigra is on the left. Note the darker leaves overall and the reddish tint to the branchlet tips and emergent leaves.

This picture better shows the typically-found form of Salix caroliniana with a large Salix nigra behind and to the left.

Botanical Descriptions of Salix caroliniana