Anacardiaceae

The Anacardiaceae is a large family of flowering plants. People often call them the cashew or sumac family. This group is very diverse and includes about 83 different genera. There are about 860 known species within this family. These plants are very important to humans for food and industry. They include many trees and shrubs found in warm regions. Some members are economically significant because of the products they provide.

Most members of this family share specific internal structures. They possess resin canals located in the inner fibrous bark. These canals are part of the fibrovascular system in stems, roots, and leaves. Many species also have resin canals in the pith. Some species even have them in the primary cortex or regular bark. Many plants also contain widespread tannin sacs. These structures help define the family's anatomy. Some plants also produce urushiol, which is a known skin irritant.

The physical appearance of these plants varies quite a bit. Most are trees or shrubs with inconspicuous flowers. The leaves can be deciduous or evergreen. They are usually arranged in an alternate pattern. Some leaves are imparipinnate, which means they have leaflets arranged along a stem. Other leaf types include trifoliolate, simple, or unifoliolate. The venation, or the pattern of veins, is also very diverse. Cladodromous venation is considered a diagnostic feature for this family.

Flowers in the Anacardiaceae have specific parts. They grow at the ends of branches or from where leaves join stems. The flowers often have a calyx with three to seven cleft sepals. They also have a similar number of petals. The stamens are usually twice as many as the petals. These stamens are inserted at the base of a fleshy, cup-shaped disk. The ovaries can be single-celled or have multiple cells. The fruits are most often drupes, which are fleshy fruits with a single seed.

Scientists have spent centuries classifying these plants. In 1759, Bernard de Jussieu arranged plants in the royal garden at Versailles. His nephew, Antoine Laurent de Jussieu, published a scheme in 1789. In 1818, Robert Brown described a subset called Anacardeæ. He used a herbarium collected by Christen Smith during a Congo River expedition. Augustin Pyramus de Candolle expanded this in 1824. Finally, John Lindley adopted the name Anacardiaceæ in 1831. He described the "essential character" of the Cashew Tribe.

This family is mostly found in tropical and warm regions. Many species are native to the tropical Americas, Africa, and India. The genus Pistacia and some Rhus species live in southern Europe. Rhus species are also found in much of North America. The genus Schinus lives exclusively in South America. Some members are highly useful for humans. We eat cashew nuts, mangoes, and pistachios. The genus Pistacia was once its own family, Pistaciaceae. However, molecular studies now include it in the Anacardiaceae.

Beyond food, these plants provide many industrial materials. The Chinese lacquer tree produces a sap used for lacquerware. Some members produce a viscous fluid used for varnish. This fluid can be used for tanning or as a mordant for red dyes. The name Anacardium comes from Greek roots. "Ana" means upward and "cardium" means heart. This refers to how the nut or heart of the fruit is located outwardly. This connection between biology and human use makes the family very important.