African Sumac

Cashew nut, mango, pistachio

African Sumac ( _Rhus lancea_, syn. _Searsia lancea_) is one of the most commonly planted evergreen shade trees in Arizona and one of its most distinctive allergy contributors because of when it blooms. While most Arizona allergens peak in spring, summer, or fall, African Sumac releases pollen during the heart of winter, with peak bloom confirmed by the UA Arboretum in January and February. This makes it a primary driver of Arizona’s winter allergy season, alongside Juniper and Arizona Cypress, and a tree that catches many residents off guard when their symptoms persist through the cooler months.

The tree is dioecious (only male specimens produce pollen) but because male and female plants are visually indistinguishable when young, and because the species has naturalized extensively in Arizona riparian areas and urban landscapes, pollen exposure is difficult to avoid. The Southwest Valley Municipal Authority (SWVMA) notes that it “produces copious amounts of allergenic pollen,” and the Sinus & Allergy Wellness Center specifically flags it as an Arizona allergen that causes “constant sneezing” in reactive individuals. ASU’s landscape plant guide states that “some people find African sumac to be a source of allergies due to the pollen from male flowers during desert winters.” Three Timbers Landscape Materials, a Phoenix nursery, advises customers to plant it away from primary outdoor living areas if allergies are a concern.

As a member of Anacardiaceae, African Sumac shares allergenic protein similarities with cashew, mango, and pistachio. Published cross-reactivity literature lists the _Rhus_ genus alongside these Anacardiaceae members, suggesting that patients sensitized to African Sumac pollen may have overlapping sensitivity to these tree nuts and fruits. It is not related to Poison Sumac ( _Toxicodendron vernix_) and is not toxic on contact, though its leaves have a faint resinous aroma when crushed.

Beyond its allergy profile, African Sumac carries a notable ecological concern in Arizona. ASU classifies it as having “moderate to high invasive potential in urban areas and surrounding riparian habitats of central Arizona,” with seeds germinating readily wherever seasonal water is available. UA Cooperative Extension explicitly recommends considering its removal. For allergy-sensitive homeowners, lower-pollen native alternatives like Desert Willow, Desert Ironwood, or Chitalpa offer comparable shade performance without the winter pollen burden or invasive spread risk.