Background
Sersia lancea, the African sumac, is a common tree around the valley - the strong fragrance of its diminuitive flowers remind me strongly of spring time as a kid growing up in Phoenix. The tree is relatively unassuming, no showy flowers in the spring and no vibrant colours in the fall. Like most invading trees, it was originally brought to the valley in the 60s as a landscape tree. I’d venture to guess that most homes built in the 60s and early 70s had an African sumac planted prominently in the front yard or back yard.
As can probably be deducted from the common name, it is one of the most common trees in South Africa. In the native range, livestock that graze too heavily on the leaves will develop a foul taste in their milk. The bark, leaves, and twigs provided indigenous groups with a valuable source of tannin for leather making. The sumac’s hard wood was used for making bows and weaponry, and also as fenceposts - and it’s easy to see why when looking at the long, slender water sprouts.
The African sumac is in the Anarcadiacea family, which is the same family as cashews, mangos, pistachios, and poison ivy. I’ve read in various online sources hints that the peppercorns of the African sumac have been used as a spice, and even used as one of the main ingredients in a type of honey mead - although despite my best googling I was unable to find more information to back up this claim.
The African sumac’s botanical name, Sersia lancea, was formally Rhus lancea. Rhus is the latin word for sumac, and lancea was a type of spear used by Roman infantry - a reference to the shape of the leaflets. The tree was formally renamed to Sersia in the early 90s in honor of the botanist and author Paul B. Sears.
The tree is very easily propogated by the peppercorn-like seeds, which is a problem because birds love these seeds. So, naturally, in any area in Phoenix where there is water, you’ll see these trees sprout up. Unlike the lead tree, they don’t grow excessively fast, and they do not reach maturity and start producing pods as rapidly. If there is a regular source of water, like a drainage ditch or desert wash, these trees will establish themselves and easily crowd out the much slower growing native vegetation.
Identification
Sersia lancea, in the Phoenix area, is an evergreen tree, that usually grows to be between 20ft and 25ft (6 to 8m) tall. It will, however, with regular water (like in a grassy lawn or with flood irrigation) grow much larger - easily surpassing 30ft (9m) tall.
The easiest way I’ve found to identify this tree is by its leaves. It is by far the most common tree in the valley with trifoliate leaves, which to me look like chicken feet. The leaflet margins (edges) are entire (smooth), the top of the leaves are dark olive green, and the bottoms are a pale olive green. During the warm summer months the tree will shed an almost obscene amount of dry, dead leaves.
The bark of this tree is usually rough and fissured, with younger wood being smooth and light brownish grey. The flowers are small and unassuming, and branch out diagonally from the stems amoung the foliage and on the ends (axillary and terminal). The flowers have a distinct fragrence, sweet and warm. The seeds are technically a drupe, and are usually seen as clusters of white peppercorns (don’t eat them!).
There aren’t too many trees that look similar to this tree - although at a casual glance it could be mistaken for a willow acacia (Acacia salicinia). The leaves of the willow acacia look very much like the leaflets of the African sumac - but that’s about it. Willow acacias are usually much taller, and have a much more upright form than the usual splayed out form of the African sumac.
Sources and further reading: