Ontario Trees & Shrubs website

The Monday Garden
Ailanthus & Staghorn Sumac

Issue No. 148 - January 23, 2005
by Sue Sweeney

Ailanthus (Ailanthus altissima), the Tree of Heaven, Asia, and Brooklyn is often considered by naturalists and homeowners alike to be a menace to society with little redeeming value for wildlife. In contrast, the staghorn sumac (Rhus tyhina) is a great native American, as useful to humans as to the smaller residents of the sub/urban environment. The black walnut (Juglans nigra), another great native American, is cultivated in the wild by squirrels who adore these tall, graceful hardwoods as much as humans do. The ailanthus is from the Quassia family of tropical plants, the staghorn sumac is a cashew family member, and the black walnut comes from the walnut family which includes hickories and pecans.

Picture: In the Hoyt Street Alley, young ailanthus (Ailanthus altissima) leaf out in front of the alley’s resident wild crabapple and shaggy bark hickory. Note the bright red-orange color of the new leaves; the greenness of the young trunks and the polka-dot pattern of the lenticels (pores). Stamford CT 2004

The ailanthus, staghorn sumac and black walnut come from totally different families and backgrounds, but can you tell them apart? All three have long, palm-like compound leaves but there are difference in flower, fruit, bark, bud, and leaf shape. This article covers the ailanthus and the sumac. The black walnut will be the subject of a future article.

AILANTHUS: Graceful, tropical-looking ailanthus is the tree that grows in Brooklyn, and just about everywhere else (including Africa and Australia). It’s as much a part of the urban landscape as the Norway rat, the cockroach, and the feral cat. Ailanthus was featured in "A Tree Grows in Brooklyn" where this arboreal immigrant’s determination to survive and flourish despite all odds gave inspiration to immigrants of the human species. In Brooklyn, I once saw a ghostly ailanthus sapling growing out of the dirt floor in a lightless sub-basement. Ailanthus saplings waving from roof gutters and fire escapes are common inner-city sights.

pictures: mature ailanthus at Stamford Cove Island. Summer and fall 2003; January 2005.
As a long-time Brooklyn resident, I have a fondness for my old neighbor, the "Tree of Heaven", as it is known in its native China. In China, the mature trees are valued as ornamentals; and the tree is used for lumber, firewood, medicine, and silkworm farming. (The wood, by the way, is similar to ash in look and quality, and actually is quite useful.) Conversely, in Virginia, where it threatens new forests, ailanthus is known as “stink-tree”.
Unfortunately, like many back-alley denizens, ailanthus is “armed and dangerous”. Ailanthus uses its wind- and water-borne winged seeds (samaras) to spread into surrounding neighborhoods. Once it gets established, it spreads into a grove by means of underground shoots. Ailanthus is a proven allelopath; it uses chemical warfare to control its turf. The chemicals it makes can ward off at least 70 other species that could compete with it for space.
pictures: new ailanthus seeds at Cove Island are very red; the older ones on Stamford’s 3rd Street have faded to tan –gold.

Detail of seeds.

picture: Tropical looking ailanthus “under-planted” with mugwort Cov e Island Summer 2003
pictures: ailanthus’ up-swept branches Cove Island, Hoyt Street Alley and Cove Island, Winter 2004-05; Morgan Street Summer 2004
Ailanthus, however, can not tolerate deep shade, so despite its chemical armaments, it can’t compete under the thick forest canopy. Instead, ailanthus tends to grow in the sub/urban environment where few trees can compete with ailanthus for ability to withstand urban pollution. Ailanthus can also out-compete native trees when the forest canopy has been disturbed by logging or fire, and it can gain a foot-hold at the forest’s edge by out-competing and poisoning other “pioneer” and edge-of-forest plants. According to the US Forest Service, in China, ailanthus only grows “in a densely populated area of China where no wild lands are left.” Chilling thought.
picture: short, stubby curved branches of a mature ailanthus; the feathery structures are last year’s flower stalks. Hoyt Street Alley, January 2005.
Ailanthus was first imported into North America, they say, in the 1700's, and was widely planted in cities (on purpose!) because it was pollution-hardy. Today, ailanthus is found in this hemisphere, in Zones 4 to 8, from Argentina to Canada. In the USA, it’s found everywhere except the really cold places such as Alaska, Idaho, the Dakotas, and Minnesota. Ailanthus is still useful for ground stabilization in pollution-prone industrial sites but I doubt anyone has to take the time to plant it.

Ailanthus is a fast, fast growing tree that lives only 25 to 50 years but it can get very large - 60 to 100 feet--in that time. While the individual trees aren’t’ that long lived for trees, the ailanthus groves can sustain themselves for hundreds of years.

Most American wildlife hasn’t much use for the foreign-born ailanthus. Even white tail deer and grey squirrels aren’t partial to it. A couple of bugs of Asian origin munch on it (and presumably are then munched in turn by birds and small animals). Honeybees (a European import themselves), though, do relish the pollen which makes quality honey after it’s been aged.

Ailanthus is weedy and aggressive; it should be controlled for the sake of the environment. In particular, the female plants which send out the seeds should be kept cut to the ground. Further, the trees are not desirable around human dwellings. Larger trees can be a winter/wind hazard and the water-seeking roots have been known to interfere with sewer lines and wells. The roots are also said to give water an unpleasant taste. The males flowers have a strong order often considered disagreeable (hence the name “stink-tree”). Ailanthus sap can cause dermatitis and the tree is a 9 out of 10 on the bad-for-allergies scale. 

pictures: vertical striped grey- clay colored bark of a young ailanthus, detail of same Morgan Street Winter 1004-05
However, there’s good in all of us, and the USA Forest Service reports that “pharmacological research is focusing on possible use of ailanthus extracts for treating cancer, malaria, and HIV-1 infection.

STAGHORN SUMAC: Lovely, graceful, staghorn sumac (no relation to poison sumac) is valued in North America and Europe as a beautiful ornamental that also provides for winter survival food for wildlife. It is an important source of food for many wild ones including skunks, songbirds, grouse, deer, and rabbits.

pictures: staghorn sumac in the wind at Cove Island (note the light color to the underside of the leaves); in flower at Scalzi Park and in the fall at Cove Island. Stamford CT 2003.
Humans have also found use for the plant. Staghorn sumac berries are so high in tannin that they can be used for tanning. Native Americas made a lemonade-like drink from them. The European colonists reportedly used sumacs to make ink. The branches are easy to hollow out and useful as temporary pipes, kids’ toys, handicrafts, and the like.

Staghorn sumac’s natural range is eastern North America, from southern Canada to Georgia. It is hardy in Zones 4 to 8, just like ailanthus. Also like ailanthus, staghorn sumac is a “pioneer” and an edge-of-forest plant. Staghorn sumac seeds are carried between locations by the wild critters which eat its seeds, rather than by wind like the ailanthus. But like ailanthus, once established, staghorn sumac spreads into a grove by means of root suckers. Staghorn sumac likes rocky, sunny, dry hill sides and banks with a neutral or high PH (limestone) content. Ailanthus isn’t particular about soil conditions, so it does both wet and dry, acid and limey. However, staghorn sumac can probably survive in soil that is more alkaline than ailanthus can tolerate and, conversely, ailanthus’s range extends farther into acidy soils and wet soils than the staghorn sumac can tolerate.

Staghorn sumac, like ailanthus, is a sun-seeker that can’t tolerate dense shade. While ailanthus does in the competition with chemical warfare, sumac uses shade. Staghorn sumac groves create such dense shade that few other plants can survive underneath it. Ailanthus groves are also dense and shady. Both ailanthus and sumac groves are too shady for their own young to survive.

picture: staghorn sumac fruit; note the downy leaf and flower stalks
picture: trunks of young ailanthus mixed with young staghorn sumac on Bedford Street in Stamford CT January 2005. The sumac are a dusty red-purple; the ailanthus are greenish, gray, and orange-brown.
IDENTIFICATION: Staghorn sumac and ailanthus not only have several similar physical characteristics, they tend to grow in similar places. It’s very important to be able to tell the trash (ailanthus) from the treasure (staghorn sumac) when deciding which plants to destroy. While ailanthus and staghorn sumac have many similarities, if you look closely there are also differences.

Height: Staghorn sumac seldom grows higher than 15 feet in the north and 35 feet in the south; so you can count on the tall ones (up to 80 feet), being ailanthus.

Form: Both ailanthus and staghorn sumac have slender, straight trunks, and upward curving branches with blunt ends. The staghorn sumac’s branches and leaf stalks have a velvet coating like deer antlers in winter, hence the name. Ailanthus branches come in whorled tiers; the staghorn sumac has a few stout branches, unusually arising at a “Y” angle from a single crotch. Mature ailanthus have rounded crowns; staghorn sumac’s are more flat-topped.


pictures: to the left is the lenticel pattern of a young staghorn sumac; center shows the sumac’s bud and dusty reddish bark; on the right is a young ailanthus – note the light colored lenticels and the smile-shaped leaf scars.
Bark- saplings: The young trunks on both plants have smooth bark dotted with lenticels (pores); the lenticels of the ailanthus are light colored and so pronounced as to give the trunk a polka-dot appearance. The sumac’s lenticels match the bark color. The young ailanthus bark is a grayish clay color or a bit orangey. The young staghorn sumac’s bark has a whitish bloom over a light colored, thin, smooth bark with purple undertones.

Bark- mature plants: the bark on “teenage” ailanthus has a diamond pattern sometimes compared to a cantaloupe’s skin; older Ailanthus become craggier and has a vertical pattern. The staghorn sumac’s bark develops horizontal streaks with age and darkens but remains smooth, and is sometimes scaly or peeling.

Leaves: Ailanthus and staghorn sumac have alternate, compound leaves that are 1 to 3 feet long with 9 to 29 leaflets. The 3” to 5” leaflets are odd in number – arranged in opposing pairs along the leaf stalk with a single terminal leaf. The ailanthus, though, has smooth-edged leaves, often with a single lobe at the bottom; staghorn sumac leaves are toothed.

Fall color: Ailanthus turns yellow and tan in the fall; staghorn sumac turns red, ranging into purples and oranges.

picture: left is a staghorn sumac; center and right are ailanthus twigs in winter. Note the sumac’s new buds are in the center of the scar from last years, leaf; the ailanthus buds are at the top of the old leaf scar.
Flowers and fruit: The two plants have completely different fruit. Both have greenish flowers at the branch tips. The ailanthus’ come in whitish-green foamy plumes. As mentioned the male flowers stink. The staghorn sumac’s flowers come in tight lime green pyramids. Ailanthus flowers mature, on the female plants only, into gold clusters of winged seeds tinged with rust (aging to light tan); staghorn sumac has fuzzy berries that go from lime to deep red.

Leave scars and buds: Believe it or not, comparing the leaf scars and buds points out the most interesting difference between these two trees and a few others. Ailanthus leaf scars are smile- or shield-shaped with the new bud at the top of the scar; staghorn sumac leaf scars are closer to heart-shaped and, amazingly, the new bud is right in the center of the old scar! The sumac buds are usually hairy if you look closely enough.

pictures: left is the terminal leaf of a staghorn sumac; to the right is the same for an ailanthus. Note that the sumac has a toothed leaflets, but the ailanthus’ has only lobes at the bottom of the leaflets.
pictures: left and center staghorn sumac; right is ailanthus.
picture: detail of emerging ailanthus foliage spring 2004.
From The Monday Garden. Copyright © by Sue Sweeney. Reproduced with permission. 

More articles from The Monday Garden

"The Monday Garden" is a FREE email publication published by Sue Sweeney. Visit The Monday Garden website