Rhus aromatica, Fragrant Sumac- 5 (1)

By Catherine Siddall

My earliest encounter with fragrant sumac (Rhus aromatica) taught me that fragrant does not necessarily mean sweet-smelling. I was asked to prune some unruly specimens that were encroaching on a stairway and I left smelling pungent with the shrub’s peculiar earthy, resinous odour. A few of fragrant sumac’s other names – polecatbush and skunkbush, for instance – make reference to what some have called its “malodorous” qualities. I wouldn’t go that far, but neither would I recommend sticking your nose in the blooming flowers to sample their fragrance or rubbing the leaves for pleasure.

In fact, some people come away with itchy skin after contact with this plant and my exposed forearms did develop a temporary rash after my pruning efforts. This characteristic is not unexpected when you realize that fragrant sumac is a close relative of poison ivy (Rhus radicans, synonymous with Toxicodendron radicans). The list of North American tree species in the same family includes several plants with “poison” in their common names, although these have been helpfully grouped under the genus Toxicodendron – a name that should warn of the plants’ nasty properties. To help with identification, fragrant sumac has three-part compound leaves, like poison ivy. Both differ from the innocuous taller sumacs whose large pinnately compound leaves can have as many as 27 leaflets.

Although the fragrance may be unappealing, and the allergenic properties a possible concern, I have developed a great admiration for the many useful and distinctive qualities of fragrant sumac. It shares with the other sumacs characteristics we easily identify with this group of plants: compound leaves that turn variable colours (orange through deep red) in fall, fuzzy red fruit, curving branches and a suckering habit. However, it is distinctly different in other respects. It matures to about 1.5 metres (five feet) in the more northern part of its range (from Manitoulin Island to the west and Ottawa Valley to the east in Ontario). By contrast, I have seen staghorn sumac specimens (Rhus typhina) over three metres or 10 feet high. (Some references say they can grow over 12 metres or 40 feet.)

While the larger sumacs tend to sucker prolifically, and rapidly form colonies in full sun locations, fragrant sumac is slower to develop suckering growth and will eventually form a dense shrub even in a fair bit of shade. It is not prone to any serious pests or diseases. I have never even seen a nibble on the leaves, a testament to the plant’s tough nature. These characteristics alone make it an excellent choice for difficult shady spots in low-maintenance gardens or naturalized sites. What’s more, like the other sumacs, fragrant sumac is tolerant of a wide range of soil conditions and is often found in infertile soils that receive little moisture. It has a great ability to cling to slopes, serving to stabilize the soil with its shallow fibrous root system. It is a relatively short-lived pioneer species that will thrive in difficult conditions, preparing the way for longer-lived trees and forest plants.

Like other members of the Rhus genus, the female R. aromatica bears a fuzzy red cluster of fruit, but it’s smaller: the round terminal mass of fruit is only four centimetres (about 1 1/2 inches) in diameter. The yellow clusters of flowers appear early in spring. The tan-brown male catkins develop during the summer and persist through fall and winter. I have never found any plants identified as male or female when purchasing them from nurseries. To increase the odds of planting at least one female that will produce fruit, it is recommended that you purchase a minimum of two specimens. Although birds obviously don’t relish the sumac’s fruit as much as they do serviceberries (Amelanchier spp.) or other tastier types, both the stems and fruit are eaten by many species of wildlife. A manual for environmental designers on North American native trees and shrubs, written by Gary Hightshoe, rates fragrant sumac’s wildlife value as very high, saying it provides “winter food for many upland game birds, songbirds, large and small mammals, hoofed browsers”.

Humans have also found many uses for fragrant sumac over the centuries. First Nations Peoples took advantage of the astringent properties of the leaves and bark by making poultices. The root was made into a concoction to treat diarrhea. The bark and berries were used in medicines. Due to the high tannin content of the leaves and bark, fragrant sumac was used for dye and for tanning leather. The fruit can be made into a tea that tastes rather like lemonade.

Fragrant sumac has an extensive range that includes all of the United States east of the Rockies as far south as Kansas and Louisiana, and north into Ontario and southwestern Quebec. Although there is little concern about its rarity throughout most of its range, in Quebec the small population is listed as threatened. Rhus aromatica is cold-hardy to USDA Zones 3 or 4.

Virtually all the gardens and naturalization projects I have designed include fragrant sumac. I find there are always one or more areas that will benefit from the addition of this tough plant with its fall colour interest. Often it is relegated to a “trouble spot” with low light levels, poor soil and dry conditions. I have used it successfully on a steep south-facing slope under oaks and maples where little else survived.

Fragrant sumac is growing well on a strip of inhospitable land sandwiched between a railway corridor and a busy Toronto street. My business partner, Michelle Cope, and I designed this particular naturalization project for local residents who had raised the money and enthusiasm to plant these public lands with native plants. In another of our projects, Rhus aromatica is expected to survive in an area in a small park that is exposed and dry, and has had trucks run over it several times. Fragrant sumac has a greater chance of taking the abuse than the other plants and may act as protection for them.

Michael Dirr, author of The Manual of Woody Plants, says of fragrant sumac that although it is “somewhat of a second-class citizen”, he “cannot remember any (of the hundreds he has seen over the years) that were offensive”. He adds: “I suspect that when a planting becomes overgrown it can be easily rejuvenated with a large mower, bush hog or other instrument of destruction”. I hope nothing like this happens to any specimens I’ve planted, but then again, I won’t object or worry if deer decide to chow down on them over winter.

Catherine Siddall designs, builds and maintains gardens. She is a long-time member of the Toronto and Parkdale Horticultural Societies and NANPS. Catherine is a partner in Siddall and Cope which offers services to groups wanting to establish community gardens or naturalization projects. Call her at (416) 531-2253 or siddall.c@sympatico.ca