“Junk trees” to some. “Weeds” to others. “An amazingly versatile gift from Nature…filling up space outdoors for free” to me. This is the genus Rhus (Sumac). In the Northeast staghorn sumac (Rhus typhina) or one of its relatives will be among the first trees in the seed bank to sprout and reach for light, or spread from a remnant stand, after mowing is abandoned in a field or lawn. Late to leaf out, they are the earliest and probably the most vibrantly red fall color.
Native sumacs are all cloning species, and if left to grow, form the characteristic soft rounded mounds of that growth habit…mother stems the tallest in the center, and younger stems subsequently shorter and shorter toward the edges.
The cloning habit is a blessing where you need the species to do its thing, and a nuisance where you don’t. It also makes the plant very hard to dig (with owner’s permission), because most stems in any one clone will have roots that look like a T, connected to one older and one younger stem and without feeder roots, each member supported by the vitality of others. It may also be the reason this genus is difficult to find in nurseries. This may change, because Rhus cultivars (called “upgrades” in the article) have just been featured in the August issue of Landscape Architecture Magazine. And for a pioneer species that can thrive in poor and excessively well drained soil, I rarely see a successful stand where it has been specified to be planted en masse, such as a highway right-of-way. In other words, if you have it on a site and want to keep it, favor what is there and let it expand, rather than count on replanting.
Sumac is especially welcome in children’s play gardens or schoolyard habitats, as it grows fast, and even as a young plant can seem like a forest to a pre-schooler. So the effect of woodland is achieved, and the custodian, who usually worries about taller trees and their leaves in the gutters, need not be concerned. A sumac stand is very resilient and can take the inevitable trampling, but one innovative pre-school director simply laid strips of old carpet along paths over a low earth mound populated by volunteer sumac.
We have encountered the common misconception about all sumac species, however, when a PTO member expressed the concern “But it’s poisonous!” Understandable mistake, but not true in most situations. There are some toxic Rhus species, now named Toxicodendron, but the two tree/shrub forms are in swamp habitats – T. vernix (Poison sumac) and T. toxicodendron (Poison oak). On the other hand, poison ivy (T. radicans) is frequently a problem, but is easy to identify.
Most of the Rhus species that volunteer in Massachusetts are native to every county, with northerly and southerly ranges overlapping. Rhus typhina (Staghorn sumac) is the taller tree-form and ranges throughout zone 3a in the northeast quadrant of the US and southeastern Canada. Its dominance is replaced by the thickety tall shrub, R. copallinum (Flameleaf, Shining, or Winged sumac), in zone 5a south of Pennsylvania and Wisconsin. The slightly smaller tree-form, R. glabra (Smooth sumac), has the widest distribution of all, pretty much the entire easterly half of the US in zones 2 through 8.
All of these sumacs share the characteristic compound leaf and upright terminal cluster of flowers and fruit. Smooth and staghorn sumac are dioecious (male and female flowers on separate plants – or perhaps easier to remember, “in two houses”).
Shining sumac is monoecious and has glossy leaflets on a winged leaf stem.
Rhus aromatica (Fragrant sumac) is a shrub in that special design niche of three-foot-tall woody plant and is common to circumneutral soils in eastern mountains plus south-central US (zone 4a). Its recumbent branches grow long and then curve up at the ends…it is beautiful as a low hedge at the top of a retaining wall, where the branches can hang down.
It is most commonly dioecious, and its three leaflets more resemble poison ivy than its tree-sumac cousins. The leaflets, when crushed, have a pleasant smell.
Be careful – this one is often mislabeled in a nursery, when it is actually R. trilobata, aptly named ill-scented sumac or skunkbush, which grows stiffly upright to six feet from the get-go and unpleasant-smelling leaves when crushed. This is one case when I would specify the cultivar R. aromatica ‘Gro-Low’ to assure the desired species and low height.
Britton, N.L. and A. Brown. (1970) An Illustrated Flora of the Northern United States and Canada, Vol. II. Dover Publications, Inc., NY.
Hightshoe, Gary L. (1988) Native Trees, Shrubs, and Vines for Urban and Rural America: A planting design manual for environmental designers. Van Nostrand Reinhold Company, Inc., NY.
Sorrie, Bruce and Paul Somers (2000) The Vascular Plants of Massachusetts: A County Checklist, MA Dept. of Fisheries and Wildlife, Natural Heritage and Endangered Species Program (but out of print).
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