Black willow (Salix nigra): what the agencies record

This page reports what US federal publications say about one tree. It does not identify trees from descriptions or photos and does not say what should be done with any tree. The family overview, tree species in the agency records, explains the sources and holds the comparison table.

At a glance

Item	What the source records
Scientific name	Salix nigra Marsh., willow family (Silvics)
Other names	Swamp willow, Goodding willow, southwestern black willow, Dudley willow and sauz (Silvics)
Native status, USDA PLANTS	Native in Canada and in the lower 48 states
Size, Silvics	Tallest trees 43 m (140 ft) and largest diameters about 122 cm (48 in); in the north and on poor sites in the south generally 9 to 18 m (30 to 60 ft) tall and 15 to 46 cm (6 to 18 in) in diameter
Age, Silvics	Greatest age recorded 70 years for a sound tree and 85 years for an unsound tree; average tree mature at 55 years
Green weight of the wood, NRS-38	51 lb per cubic foot, without bark

Native range and where it grows

The Silvics of North America handbook (Agriculture Handbook 654, 1990) calls black willow the largest and the only commercially important willow of about 90 species native to North America, and says 27 species reach tree size in only part of their range. It records a range through the eastern United States and adjacent parts of Canada and Mexico, from southern New Brunswick and central Maine west through Quebec, southern Ontario and central Michigan to southeastern Minnesota, south and west to the Rio Grande just below its confluence with the Pecos River, and east along the Gulf coast through the Florida panhandle and southern Georgia. The handbook says the tree reaches its maximum size in the lower Mississippi River Valley and the bottom lands of the Gulf Coastal Plain, and that some authorities treat Goodding willow as a variety, which would extend the range to the western United States.

Silvics says strict needs for seed germination and seedling establishment limit black willow to wet soils near water courses, especially floodplains, where it often grows in pure stands. It is most common on river margins and in swamps, sloughs and along bayous and ditches, and the handbook says it flourishes at or slightly below water level and is not appreciably damaged by flooding and silting. It names one forest cover type for it, Black Willow (Society of American Foresters Type 95), a temporary pioneer type.

Flowers, seed and cuttings

The species is dioecious. Silvics says flowering runs from February in the south to late June at the northern limits, with catkins appearing at or just before leafing out and pollination mainly by insects. Small light-brown capsules split open 45 to 60 days after pollination. The handbook says seed production starts at about 10 years, the best seed-bearing age is 25 to 75 years, and good crops come almost every year. Minute seeds with silky hairs travel very long distances by wind and water, and unless the seed lands on water it must reach a seedbed within 12 to 24 hours because a few days of dry conditions greatly reduce viability. The handbook calls propagation by cuttings the usual method of artificial regeneration, and says post-size willow cuttings have been rooted for use in flood projects.

Growth and roots

In natural stands of the lower Mississippi Valley, Silvics gives average trees of 15 m (49 ft) in height and 14 cm (5.6 in) in diameter at 10 years, and 31 m (101 ft) and 49 cm (19.4 in) at 40 years. In well-stocked stands on the best alluvial soils the trunk is acceptably straight and clear of limbs for an average of 12 m (40 ft), while open-grown trees and those in swamps are generally limby. The handbook calls black willow a very weak tree, especially prone to breakage, and says almost all large trees have large broken limbs. It describes the roots as shallow, especially on clay-capped alluvial soils, and says floods can bury the trunk while new roots form from buds on the buried part. It classes the tree as very intolerant of shade and says stands not properly thinned may lose up to 50 percent of their volume over 5 to 8 years.

Wood

The Wood Handbook (FPL-GTR-282, 2021) says most black willow comes from the Mississippi Valley, from Louisiana to southern Missouri and Illinois, and that it is the only willow marketed under its own name. The heartwood is grayish brown or light reddish brown, often with darker streaks, and the sapwood is whitish to creamy yellow. The wood is uniform in texture, somewhat interlocked in grain and light in weight, with exceedingly low strength as a beam or post, moderately soft and moderately high in shock resistance. Silvics lists boxes and crates, furniture core stock, turned pieces, table tops, slack cooperage, novelties, charcoal and pulp, and says the wood was used extensively for artificial limbs because it is lightweight and does not splinter easily. It also reports that the glucoside salicin was isolated from willow in 1829.

Wood Handbook figure	Green	At 12% moisture content
Specific gravity (Table 5-3b)	0.36	0.39
Modulus of rupture, lbf per square inch (Table 5-3b)	4,800	7,800
Side hardness, lbf (Table 5-3b)	Not published	Not published

The green weight is in the NRS-38 table, the same figure used in the log weight calculator.

Damaging agents the handbook names

Silvics says several insects attack live willow but few cause serious damage.

Defoliators. The forest tent caterpillar, gypsy moth, cottonwood leaf beetle, willow sawfly and imported willow leaf beetle, which sometimes partly and occasionally completely defoliate willows, reducing growth but seldom killing.
Borers. The cottonwood borer, which attacks stems and may kill by girdling the base, and the willow-branch borer, which feeds on branches and causes deformities.
Diseases. Willow blight (scab and black canker) from Pollaccia saliciperda, transmitted by borers; bleeding canker from Phytophthora cactorum, which can kill if it girdles the trunk; cytospora canker, which the handbook says is of little consequence under forest conditions but can cause heavy losses in weakened trees (see cytospora canker); leaf rust on seedlings; and mistletoes that damage and deform but seldom kill.
Fire and rot. Hot fires kill entire stands, and slow light fires wound trees and let wood-rotting fungi in. The handbook says top and branch rot account for 86 percent of the cull in willow.

For who takes reports of regulated pests, see reporting a pest in the United States, and pests and diseases by country sets out which ones agencies regulate.