Staghorn Sumac (Rhus Typhina)

Issue: 
March-April 2009

THERE TENDS TO BE SO MUCH SUMAC in our landscape that familiarity leads to oversight. Yet, look around – roadsides, old fields and disturbed places are home to thickets of this small tree bearing its stout terminal twigs plush with velvet. In the fall, the leaves turn bright scarlet and all winter long, the fruits make a ruddy splash of colour. It seems that the name “sumac” derives from Arabic and that the Arabic word refers to the colour, even if of a different species. Often overlooked because it is so common and because it is plant of weedy sites, staghorn sumac has lots to commend itself.

The species owes its name to the aforementioned velvety stout terminal branches. They look like stag’s antlers before the velvet is shed. Unlike most deer (caribou and reindeer are the exceptions), both male and female plants sport velvety antler-like branches. Yes, the plants generally come in two sexes. The differences between the sexes can be seen in early summer when the plants bloom, and especially late in summer through winter when only the female plants support the bright red, tight and conical clusters of small fruits. The approximate sizes of the clonal thickets can be estimated by the sexual expression, though there is no reason to suppose that more than one clone of a given sex should not grow mingled with, or alongside, another of the same sex.

Rehabilitation & Landscape Agents
Staghorn sumac may be a weed to some, but it is a boon to others. Because it grows in disturbed sites, it is an important agent of environmental rehabilitation. Sumacs colonize road cuts, embankments, old fields, rights of way, gravel pits – anywhere the soil is poor and disturbed. The seeds germinate readily after passing through the alimentary tracts of birds. The young plants grow rapidly and establish, becoming well branched treelets (that is, mostly with a single trunk rather than multiple stems that characterize shrubs) that rarely exceed 6 m in height and with trunks around 10 cm in diameter.

Once established, they propagate themselves into thickets by their shallow, wide-spreading and suckering root system. They bind the soil, contribute carbon to soil rebuilding, allow other sun-intolerant trees to establish in their shade, provide wildlife habitat and food, and die young to allow for the release and growth of the longer-lived and larger trees they have sheltered.

Yes, the same aggressive traits that allows staghorn sumac to establish and grow so vigorously can be a problem if its thickets expand into places where the treelets are not wanted, but its environmental worth outweighs its nuisance. In fact, staghorn sumac is advocated as an ornamental. The “cutleaf” sumac laciniata is a natural variant of staghorn sumac and can be used for visual effect. Its leaflets are deeply dissected, but otherwise similar to those of the normal plant.

Staghorn sumac is as “tough as nails,” drought hardy, makes a thick privacy stand for property boundaries, can be pruned for bordering, and is underappreciated for its landscaping and horticultural potential. Some landscapers remove all the branches except those of the crowns and the resultant form is said to resemble a palm. The fall leaf colour is also much appreciated, as are the clusters of fruits and the birds that use them.

Basic Biology
The leaves of the usual type of staghorn sumac are characteristically large and pinnately compound (feather-like). Each leaflet, bright green above and silvery below, has a serrate (saw-toothed) edge. Each leaf, with its mid- and lateral- veins finely covered with hairs may have up to 39 leaflets (always an odd number because of the terminal singleton) and reach half a metre long. The leaves are characteristically compound. When they are broken, they exude a pale milky sap. The leaves are borne alternately on the branches below the flowering structure (inflorescence).

The pale yellowish-green flowering clusters of the male plants can reach about 30 cm long. They are much bigger, by half again, than the greener and more compact clusters of flowers of the female plants. Flowering starts in May and continues into June, and the fruits are ripe from July onwards. The flowers are highly attractive to a diverse array of insects that serve as pollinators. Many kinds of bees, wasps, flies and beetles can be found visiting the flowers. Staghorn sumac is a valued source of nectar for honey production. It is interesting that the flowers of the male plant provide both pollen and nectar to pollinators mostly in the morning, and the female flowers provide just nectar in the afternoon. Thus, the pollen is removed from the flowers of male plants in the morning, but after they stop secreting nectar, the insects switch their attention, and transfer pollen, to flowers of female plants when they secrete their nectar in the afternoon.

The fruits are small drupes, about 3 to 5 mm across, and combine to make a bright red, compact, conical infructescence on the tips of the branches. These characteristic bunches remain on the trees throughout winter. The colour of the fruits comes from the thin fleshy outer layer with its reddish acidic hairs. The taste is similar to unripe apples and can be quite thirst quenching on a hot summer day. That flavour is the basis for the name “vinegar tree” or “sumac vinaigrier” in French. Of course, the slatey-brown seeds within, one per fruit and up to 3 cm across, should be spat out. The ripe fruits can be steeped in water to make a sort of “lemonade” to which honey or sugar can be added to take the edge off the sour flavour. The whole fruits are generally fibrous and not that nutritious, but have been found to include about 5% protein. The fleshy outer layer contains some carbohydrate. Even though not a prime source of easily digested food, the fruits are important to many kinds of birds that feed on them, especially through the winter and early spring.

For wildlife, staghorn sumac is not only a source of fruits but also important browse for deer and moose in some places. Rabbits also eat young spring shoots, which are said to be consumed by people as salad greens.

Other Uses & Range
The wood of staghorn sumac can be used in specialty wood-working. It is light and brittle, but its orangish colour with greenish rays makes it attractive for carving and inlays. By punching out the central pith, the branches can be used as natural taps for collecting maple sap, pea-shooters for children, pipe stems, blowing tubes to brighten campfires, and perhaps even as whistles for playing music.

The bark, which is quite smooth and sometimes peals off, and leaves can be boiled down to make a dark brown ink. Adding some iron to the mash increases its quality and if iron salt is used, the ink is less likely to go mouldy. The high tannin content of the leaves and bark is useful for making natural dyes. The tannins also function as a mordant, improving the fastness of other natural dyes.

Staghorn sumac grows from the Maritimes throughout the St. Lawrence/Great Lakes forest regions of Quebec and Ontario. In the USA, it ranges from the eastern seaboard, across the Appalachian mountains into Minnesota, and south to Georgia. It has a number of close relatives in Canada including two other species of sumac, shining (R. copallina) and smooth (R. glabra), the notorious poison ivy (Toxicodendron radicans in the east) and poison oak (T. diversiloba in British Columbia) and its rare sister, poison sumac (T. vernix) which often are all placed in the same genus, Rhus (the latinized version of the Greek name of a Mediterranean sister species used for spice). All these plants belong to the same family as the cashew and mango of the tropics, the Anacardiaceae.

Our mission is to enhance and promote the care and benefit of trees for present and future generations in Ontario through education, research and awareness.