Aromas of pine, cinnamon, and clove commonly waft through the air during the holiday season. However, the woodsy, earthy fragrance of frankincense and warm, spicy aromas of myrrh are ancient scents used in religious rites for 5,000 years. In Christian tradition, they are known as two of the three gifts of the Wise Men. In ancient Egypt, myrrh and other oils were used for embalming corpses. Myrrh was also burned as a type of incense long ago by the Romans at funeral pyres. Because ancient societies of Egyptians, Greeks, and Romans burned frankincense or myrrh incense during rituals, these resins were in high demand and expensive due to the tolls, taxes, and labor expenses incurred when transporting them across treacherous routes to markets. These resins were so valuable that laborers who processed frankincense were strip-searched daily to prevent looting. Today, resins and oils from frankincense and myrrh trees are used in perfumes, cosmetics, aromatherapy, and medicines, especially in China. The demand for frankincense oil remains high, making it a $7 billion industry.
Figure 1 Resin of frankincense (left) and myrrh (right) trees.
Frankincense resin is harvested from woody species in the Boswellia genus grown in arid climates, such as Ethiopia and Somalia in eastern Africa and Oman and Yemen on the Arabian Peninsula. Closer to home, Boswellia sacra trees can be found growing in the University of Arizona campus arboretum and elsewhere in warm, arid regions in the United States. This frankincense species is a slow-growing, small tree or large shrub that grows to 16-20 feet-tall. It thrives in sandy or rocky, well-drained, calcareous soil. Sparse, compound leaves grow on scrubby branches and trunks have papery, peeling bark. In the spring, trees produce showy cream-colored flowers with 5 petals with red centers. Other frankincense species include B. serrata grown in India, B. ferenana found in the Horn of Africa, and B. papyrifera present in Ethiopia, Eritrea, and Sudan.
Figure 2 A frankincense tree at Wadi Dawkah Natural Park near Dhofar, Oman. Photo courtesy of Mauro Raffaelli. Wikimedia Commons
Most frankincense trees start producing resin at about eight to ten years of age. Incisions in trunks cause sap to ooze from these wounds as droplets or "tears." The oozing sap hardens into resin, which is scraped from the trunk. To prevent damage, trees are scored fewer than 13 times per year. In Somaliland, it is illegal to overharvest trees, but in other countries trees are unprotected. Not only are some Boswellia trees threatened by over-exploitation, but they are also vulnerable to livestock grazing and infestations of long-horned beetles. For more information, Boswellia: Sacred Trees of Frankincense by Jason Eslamieh is an interesting book.
Figure 3 A botanical illustration of Commiphora myrrha. Wikimedia Commons
Myrrh resin is primarily collected from Commiphora myrrha and other species of this genus native to Ethiopia, Kenya, Oman, Saudi Arabia, and Somalia.Commiphora myrrha is a small tree that grows 9 to 13 feet-tall. This species has greyish-green trifoliate leaves and there are long spines on its branches. Papery bark exfoliates from its trunk. Trees favor shallow soil over limestone. Like Boswellia, the bark of Commiphora trees is scored to produce resinous myrrh, which exudes from the incisions.
Seeds and plants of frankincense and myrrh are in short supply in the United States. However, nurseries that specialize in desert plants sell some species of Boswellia and Commiphora. To germinate seeds, lightly cover them with about ¼ inch of pulverized limestone in a warm area. Water seeds using a fogging nozzle daily. Germination usually occurs in about 3 weeks, but fogging should continue until the seedlings are about 8 inches-tall. Plants can also be propagated by cuttings.
Even though frankincense and myrrh trees are unsuitable for Missouri's climate, don't despair. There are many commonly-available oils, incense, and perfumes that diffuse the enticing, mystical aromas of these species not only during the holiday season but also throughout the year.