Scientific: Searsia lancea (formerly Rhus lancea)
Common: African sumac, willow rhus, black karee (indigenuous common name)
Family: Anacardiaceae
Origin: Southern Africa in Zambia, Namibia, Botswana, Zimbabwe, South Africa and Lesotho.
Invasive Alert: African sumac has a moderate to high invasive potential in urban areas and surrounding riparian habitats of central Arizona. Basically, seedlings can germinate anywhere there is constant or seasonal sources of water. Some people find Arican sumac to be a source of allergies due to the pollen from male flowers during desert winters.
Pronounciation: Se-ar CEE-a LAN-see-a
Hardiness zones
Sunset 8, 9, 12-24
USDA 9-11 (semi arid and arid ecoregions only
Landscape Use: Relatively dry landscape shade tree, transitional tree between oasis and xeric design motifs, informal large screen, hillside and/or embankment stablization and erosin control.
Form & Character: Assymetrically and informally rounded, rugged and wide spreading, sturdy yet awkwardly graceful and slightly pendulous, grey to chocolate brown trunk and large coarse schaffold branch architecture crown contrasts well with light green refined and pendulous canopy.
Growth Habit: African sumac is an evergreen, woody, broadleaf (actually leaflets quite narrow) perennial tree, moderately rapid grower to 30 to 40 feet in height with somewhat greater spread. Its growth rate and eventual mature tree size is directly related to overall water availability. Often produces a dense cluster of basal epicormic shoots when stressed (mostly by sunscald injury in Phoenix).
Foliage/Texture: Trifoliate leaf, leaflets are narrow and lanceolate to 4 inches in length, light green when young to dark green when mature; medium texture.
Flowers & Fruits: Dioecious trees (male and female flowers in separate trees), flowers greenish in winter, musty fragrance; undercanopy hidden fruit are small and reddish fading to brown in late summer.
Seasonal Color: None
Temperature: Hardy to 12oF. African sumac tolerates a wide range of temperature conditions from high heat of the desert summer to the cool maritime fog along the southern California coast.
Light: Full sun, no shade.
Soil: Tolerant of soil alkalinity.
Watering: Infrequent deep summer irrigations in desert areas. No supplemental irrigation needed in coastal maritime climates.
Pruning: African sumac will eventually extend a 'shrub-like' canopy of leaves to the ground if neglected. This means that the principal training of this tree throughout its life span will be to establish and maintain an upright and arborescent crown architecture through crown raising, LIMITED crown thinning, and removal of eipcormic basal shoots. Remember, excessive crown thinning (>20%) of trees like African sumac in lower desert locations usually causes trunk and branch sunscald injury during summer months.
Propagation: Very easy to germinate seeds.
Disease and Pests: Root and crown rots are prevalent, while aphids are a transient springtime problem.
Additional comments: African sumac is a good serviceable, small- to medium-sized landscape tree for tough urban sites that was quite popular in Phoenix during the later half of the 20th century.
Taxonomic factoid: The genus Searsia is named after Paul B. Sears (1891-1990) who was once head of the Yale School of Botany. The species name, lancea refers to its lance-shaped leaflets.
