The cashew family is more abundant in warm or tropical regions with only a few species living in the temperate zones.[4] Mostly native to tropicalAmericas,Africa and India.Pistacia and some species ofRhus can be found in southernEurope,Rhus species can be found in much ofNorth America andSchinus inhabitsSouth America exclusively.[5]
Trees or shrubs, each has inconspicuous flowers andresinous or milkysap that may be highlypoisonous, as inblack poisonwood and sometimes foul-smelling.[5]Resin canals located in the inner fibrousbark of thefibrovascular system found in the plant's stems, roots, and leaves are characteristic of all members of this family; resin canals located in thepith are characteristic of many of the cashew family species and several species have them located in the primary cortex or the regular bark.Tannin sacs are also widespread among the family.[6]
The wood of the Anacardiaceae has the frequent occurrence of simple small holes in the vessels, occasionally in some species side by side with scalariform holes (inCampnosperma,Micronychia, andHeeria argentea (Anaphrenium argenteum). The simple pits are located along thevessel wall and in contact with theparenchyma.[6]
Leaves aredeciduous orevergreen, usually alternate (rarely opposite),[4] estipulate (withoutstipule) and imparipinnate (rarely paripinnate or bipinnate), usually with opposite leaflets (rarely alternate), while others are trifoliolate or simple or unifoliolate (very rarely simple leaves are palmate). Leaf architecture is very diverse. Primaryvenation is pinnate (rarely palmate). Secondary venation is eucamptodromous, brochidodromous, craspedodromous or cladodromous (rarely reticulodromous) Cladodromous venation, if present is considered diagnostic for Anacardiaceae.[5][7]
Flowers grow at the end of a branch or stem or at an angle from where the leaf joins the stem and havebracts.[5]Often with this family, bisexual and male flowers occur on some plants, and bisexual and female flowers are on others, or flowers have bothstamens andpistils (perfect). Acalyx with three to seven cleftsepals and the same number of petals, occasionally no petals, overlap each other in the bud. Stamens are twice as many or equal to the number of petals, inserted at the base of the[4] fleshy ring or cup-shaped disk, and inserted below the pistil(s).[5]Stamen stalks are separate, and anthers are able to move.[4]Flowers have theovary free, but the petals and stamen are borne on the calyx.[5]In the stamenate flowers, ovaries are single-celled. In the pistillate flowers, ovaries are single or sometimes quadri- or quinticelled. One to three styles and one ovule occur in each cavity.[4]
Fruits rarely open at maturity[5]and are most oftendrupes.[4]
In 1759,Bernard de Jussieu arranged the plants in the royal garden of the Trianon at Versailles, according to his own scheme. That classification included a description of an order called the Terebintaceæ, which contained a suborder that includedCassuvium (Anacardium),Anacardium (Semecarpus),Mangifera,Connarus,Rhus, andRourea. In 1789,Antoine Laurent de Jussieu, nephew of Bernard de Jussieu, published that classification scheme.[8]
Robert Brown described a subset of the Terebintaceae called Cassuvlæ or Anacardeæ in 1818, using theherbarium that was collected byChristen Smith during a fated expedition headed byJames Hingston Tuckey to explore theRiver Congo. The name and genera were based on the order with the same name that had been described by de Jussieu in 1759. The herbarium from that expedition contained only one genus from the family,Rhus.[9]
John Lindley described the "essential character" of the Anacardiaceæ, the "Cashew Tribe" in 1831, adopting the order that was described by de Jussieu, but abandoning the name Terebintaceæ. He includes the genera that were found in de Candolle's Anacardieæ and Sumachineæ:Anacardium,Holigarna,Mangifera,Rhus, andMauria.[5]
The genusPistacia has sometimes been separated into its own family, the Pistaciaceae, based on the reduced flower structure, differences in pollen, and the featherystyle of the flowers.[3]The nature of its ovary, though, does suggest it belongs in the Anacardiaceae, a position supported by morphological and molecular studies, and recent classifications have includedPistacia in the Anacardiaceae.[3][11][12] The genusAbrahamia was separated fromProtorhus in 2004.(Pell 2004)
The family has been treated as a series of five tribes by Engler, and later intosubfamilies by Takhtajan, asAnacardioideae (including tribes Anacardieae, Dobineae, Rhoideae, and Semecarpeae) andSpondiadoideae (including tribe Spondiadeae). Pell's (2008) molecular analysis reinstated the two subfamilies without further division into tribes (Pell 2004). Later, Min and Barfod, in theFlora of China (2008) reinstated the five tribes (four in Anacardioideae), and the single tribe Spondiadeae as Spondiadoideae.[citation needed]
The nameAnacardium, originally from the Greek, refers to the nut, core or heart of the fruit, which is outwardly located:ana means "upward" and-cardium means "heart").[citation needed]
Aguilar-Ortigoza, Carlos; Sosa, Victoria; Angeles, Guillermo (April 2004). "Phylogenetic relationships of three genera in Anacardiaceae:Bonetiella,Pseudosmodingium, andSmodingium".Brittonia.56 (2):169–184.doi:10.1663/0007-196X(2004)056[0169:PROTGI]2.0.CO;2.S2CID25623042.
Pell, Susan K.; Mitchell, John D.; Lowry, Porter P.; Randrianasolo, Armand; Urbatsch, Lowell E. (1 April 2008). "Phylogenetic Split of Malagasy and African Taxa ofProtorhus andRhus (Anacardiaceae) Based on cpDNAtrnL–trnF and nrDNA ETS and ITS Sequence Data".Systematic Botany.33 (2):375–383.doi:10.1600/036364408784571545.S2CID86329117.