| General Description | S. nigra is the largest, most commercially important willow in Canada. It is extremely hardy, and can survive a full submersion in water for days at a time. It is short-lived, maturing at approximately 50 years and living for 75. The average recorded height is 12 m, however it may range from 10 – 30 m depending on environmental conditions. The most impressive and vigorous specimens are located in the United States of America near the Mississippi river. |
| ID Characteristic | The colour of S. nigra's leaf is one of its main identifying characteristics, especially when differentiating between members of the Salix genus. The leaf is a deep green on both sides, where other willows generally have a paler underside. The leaves also have a tendency to curve back at the tips. Near the base of the petiole, one can see persistent reniform stipules. When leaves are not present, one can note the dark-grey, almost black colour of the bark. One of S. nigra's biggest look - alikes is the crack willow (Salix fragilis). |
| Shape | S. nigra can come in both single and multi-stemmed forms. It tends to develop the multi-stemmed vase-like shape when given the room to spread. Otherwise, it holds its domed crown above the ground on a single, longer trunk. S. nigra self-prunes very well, and lower branches are removed through breakage. Its tendency for its spreading branches to break away gives the more mature trees an irregular, broad, spreading crown. |
| Landscape | S. nigra is not recommended for urban landscape use. This is due to the large amount of debris it leaves behind. It can be used if you have a depressed, poor draining area in the land you would like to scape, however there are “cleaner” options for that location.
S. nigra is particularly picturesque when leaning over a pond or river bend. S. nigra is well suited for naturalization projects. As the tree matures, it drops more material, which benefit the soil and soil-life when they rot. S. nigra's dense, sturdy root system makes it ideal for erosion-control projects in naturalized areas.
S. nigra is very shade-intolerant, except within its first year of growth, where adequate shade is required for germination. Being a tree which requires constant moisture also lends it the benefit of being flood tolerant. The Black Willow provides food for some wildlife, including snapping turtles, deer, rodents, beavers, and rabbits (bark, tender twigs, and buds). Birds may nest in the Black Willow, and bees eat the nectar of the flowers which it pollinates. |
| Propagation | The seeds of Salix nigra are very small (approximately 1 mm) and short-lived, remaining viable for only a couple of days after being exuviated by the tree. The seeds, which are produced when the tree is about 10 years old, need no cold stratification and would likely not survive such treatment for very long (about 1 month). When the seed pods (3 - 6 mm) yellow in June, the seed pods and capsule are borne unto the wind by downy white material, to settle upon the seed bed. Should this seed bed be adequately moist and shaded, most of the seeds will germinate. The seeds are also buoyant and can germinate while floating on the water. The seeds can then land on a riverbank and establish themselves.
S. nigra can be propagated by both hardwood and softwood cuttings, and by both stem and root cuttings extremely easily. Few plants can rival S. nigra’s ability to root so vigorously. Where twigs and branches break off, it is not unusual to see multiple saplings surrounding the parent tree. Some pieces of furniture, walking sticks, and other items created from Salix nigra have been known to become rooted.
Often twigs and branches float down a river and root along the bank, creating stands of genetically identical black willows.
|
| Cultivation | Black Willow will grow in many different soils as long as they are consistently wet. It has been shown that entire stands will die when the water table becomes too low.
To maximize growth, full sun, rich extremely moist soil, and a Ph of 6 - 8 should be provided.
S. nigra is shade intolerant, drought intolerant, flooding tolerant, and has a reduced lifespan in environments containing high levels of salt and pollution. |
| Pests | Bruce span worm, fir- willow rust, and hemlock-willow rust are the most serious of the willow pests and diseases, although none cause lasting, serious damage.
Other pests which can effect the aesthetics and longevity of S. nigra are: moesch, Asian longhorn beetle, flea weevil, silk moth, and the yellow bellied sap sucker. |
| Notable Specimens | In Westminster ponds, an environmentally sensitive area of London Ontario, around the marsh - thicket area of Saunders pond there are stands of red-osier dogwood (Cornus sericea), eastern cottonwood (populus deltoids) and Black Willow (Salix nigra). |
| Habitat | Wet areas with rich soil are ideal for S. nigra. Very rarely is it found in areas where seasonal drying occurs. Mostly occurring on the banks of streams and rivers, swamps, flood plains. S. nigra will flourish in any areas of full sun and constant moisture, and it is intolerant of shade. S. nigra also grows alongside: red maple (Acer rubrum), silver maple(Acer platanoides), cottonwood(populus deltoids), green ash (Fraxinus pennsylvanica), white elm (fraxinus Americana) and other willows (Salix genus). The most impressive specimens occur along the Mississippi river in the United States of America. |
| Bark/Stem Description | Black Willows are dark grey - almost black, deeply furrowed and scaled, more so in mature trees. Generally, the older the tree is, the darker and more furrowed its bark will be.
Frequently damaged by boring insects and birds, resulting in many bulbous protrusions from where the tree has healed past wounds.
|
| Flower/Leaf Bud Description | The bud is narrow, conical, sharp, pointed, shiny brown - yellow. Flower buds are larger than leaf buds. Usually, S. nigra lacks a true terminal bud. It has 1 bud scale which entirely covers the bud. Bud is a small ovoid shape which lies flat against the twig on which it is growing. |
| Leaf Description | Lanceolate, alternate, finely serrate, simple leaves with persistent reniform stipules and small (3 - 6 mm) petioles. Pinnate venation, 8 - 14 cm long, minuscule, downy hairs are on the petiole, and the base of leaf is rounded. The leaves are much more narrow than other willow species, have a long, back-curving tip, and are a key identifying feature between S. nigra and the crack willow (S. fragilis), a non-native but pervasive species. There is one leaf per node along the stem. The leaves are deep green, and have the same colour on each side. |
| Flower Description | Diocious flowers presented upon catkins (3-8 cm) which are insect pollinated, the green pods ripen to bright yellow. S. nigra is very important to honeybees as S. nigra is one of the first plants to flower in the spring.
The female flower has stigma, style, and ovary. The male flower has anther and filament, and flower buds are much larger than leaf buds. The flower lacks petals and does not produce flashy fruit, but rather a dry-seed-filled capsule.
|
| Fruit Description | The fruit comprises of brown – yellow seeds, but white before the capsule naturally splits to release them. The seeds are attached to cottony wisps to aide with wind dispersal. It takes 45 – 60 days for seeds to ripen after pollination. The minute, rounded seeds come from dry, brown, ovoid capsules. Male flowering trees do not produce seed. Catkins are 3 – 8 cm long. |
| Colour Description | The leaves are deep green on both sides, (most willows have a silvery or paler green underside). The autumn colour of the leaf is bright yellow. Young twigs can be a golden yellow – orange to an orange – red, more mature branches and stems all have a brown undertone but are considered dark grey – black when differentiating from other barks.
The buds are bright, dull brown – yellow, seeds can be brown, yellow, or white. Seed wind dispersal aide is white.
|
| Texture Description | The bark is very course and deeply furrowed, and the leaves are glossy and have a mild leathery feel. New, young twigs are smooth. The roots form a fibrous mat, and the seeds have downy, soft wisps. The small lenticles do not add greatly to the texture. |