12 November 2010

Spotlight On...Skunkbush Sumac

Skunkbush Sumac
Rhus trilobata
Anacardiaceae (Sumac Family)
Quick ID:  

Look for shrubs with wide, dense crowns, generally no more than 4' high but spreading out to 8'.  The alternate leaves are downy, dark green above and pale below, and divided into three coarsely toothed ~1" leaflets.  In spring, beginning before the leaves appear, tiny yellow flowers cluster at the ends of the stems.  These give way to clumps of hairy little red-orange fruits around mid-summer, which hang onto the stems long after the leaves have dropped.  New twigs are covered with an ochre velvet much like new antlers.  It's easy to see the plant's progression of growth when looking at the branches; each previous year's wood is smoother, more inflexible, and colored differently.  Like counting tree rings, examining the length, form and character of branches' annual growth can be an interesting peek into recent history.  Call it another way of reading, or of listening, or call it a chilly botanist's daydream on a grey November morning....
               Here is the drought year.  That piece is the summer the giant Ponderosa Pine fell down, opening the canopy to let the sunshine fall through.  This is last spring, when a mule deer nibbled the soft spring growth, see how it branches out?  And here, this fuzzy tip is what has appeared since things woke up this spring.
And so it goes... 
There are at least four varieties of Rhus trilobata found in North America (some sources recognize six), most of which are mainly clustered in the deep southwest.  Rhus trilobata var. trilobata is the only one found in Montana; its range spans from the Pacific coast eastward to the tallgrass prairie states, from southern Canada to northern Mexico, up to about 7000' elevation.  Varieties tend to be more branched and compact in the southwest part of their range, and taller in the north.  Sumac can grow in a wide diversity of habitats, from dry to mesic (moderately wet) areas, on slopes, in thickets, canyons and stream banks.
What's in a Name?
The family name Anacardiaceae is in reference to Anacardium, the cashew, and its vaguely heart-shaped fruits (cardium=heart).  Rhus, in turn, is the Greek name for sumac, which itself is ultimately derived from the Syrian summaq, "red".  The specific epithet trilobata refers to the three-lobed leaves.  Skunkbush sumac is also known as Rhus aromatica, for its supposedly horrible, skunky-smelling leaves.  Me, I've squished and sniffed these leaves a thousand times, and don't think it's disagreeable at all.  They smell green, resinous, a little like acrid pine.  Some folks won't go near it though, so, as LB likes to say, "You don't have to take my word for it."  Best to sniff for yourself.
As usual, there are too many common names of R. trilobata to list here, but depending where you live, you might also hear it called sourberry, three-leaved sumac, fragrant, ill-scented or stinking sumac, squawbush, quailbush, lemonade sumac, basketbush, polecat bush or lemita. 
This is a plant with a long history of edible, medicinal and functional uses.  Like other sumacs, the berries are super-duper sour, and fun to pop in your mouth on a hot summer day.  They taste like lemony pine needles, and can be used in drinks, bread, soup, etc.  The leaves and inner bark can be used in teas and poultices for such diverse ailments as colds, itches, stomach problems and hair loss.  A black or orange dye can be make from the roots and berries, respectively, and the flexible young branches are good for basket-weaving.
The family Anacardiaceae is full of irritating or otherwise dangerous plants, including poison sumac, poison ivy, and poison oak.  (Thanks to Fabric Guy for the informative picture.)  Poison sumac doesn't grow in the west, and wouldn't be mistaken for skunkbush even if it did.  The ranges of poison ivies and oaks, however, do overlap, and the three-leaved nature of these plants can make them hard to distinguish from skunkbush (especially the shrubby poison oak).  In general, poison oak (Toxicodendron diversilobum) and poison ivy (T. radicans) have a stalked middle leaflet, while R. trilobata's has no stalk.  They also have greenish flowers and white fruits, as opposed to yellow flowers and red fruits.  Even with well-honed ID skills, people who are super-sensitive to poison ivy should stay away from any member of the Anacardiaceae family.  Sadly, this also includes mangoes, which a lot of people are sensitive to.  I once ate so many mangoes my lips swelled up like a grouper, but that's a story for another day.
Wild Gardening:  
With its soft texture in winter, bold spring greenery, glistening red berries and brilliant fall color, Rhus trilobata is an absolute pleasure all year long.  It's fairly easy to find commercially, and naturalizes well to form windbreaks or shelterbelts.  Because of its strong root system, it's a good choice for erosion control.  Plants need full sun to part shade, room to spread, and good drainage, but will tolerate nearly any type of soil, cold, or drought.  
One of the joys of gardening with native plants is the opportunity it provides for observing backyard wildlife.  Keeping a list of birds and their arrival dates each year, discovering a cache of winter food or watching pollinators busy with their summer tasks are a delight in themselves, and knowing that you're helping conserve essential habitat by providing food and shelter is just icing on the nature-cake.  In this spirit, skunkbush sumac thickets provide great hiding and nesting cover for small mammals, and the persistent berries are an important source of food for winter songbirds and upland gamebirds.  Here at the Nature Adventure Teaching Garden, the golden Rhus, tawny chokecherry (Prunus virginiana) and evergreen mahogany (Cercocarpus ledifolius) make for a fall display that just couldn't be prettier.    

    Spotlight On... features Montana native plants that are currently on display in our natural areas.  Have a plant that you'd like to see featured?  Let us know!

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