Tree, shrubs, or lianas; usually with tannins; well-developed vertical resin canals in the bark and associated with the larger veins of the leaves, often also in other parenchymatous tissues, the resin clear when fresh but drying black, often causing dermatitis. Hairs various. Leaves usually alternate and pinnately compound, but sometimes trifoliate or unifoliolate, leaflets entire to serrate, with pinnate venation; stipules ± lacking. Flowers almost always unisexual (plants usually dioecious), radial, small, often with well-developed staminodes or carpelodes. Sepals usually 5, distinct to slightly connate. Petals usually 5, distinct or slightly connate ± imbricate. Stamens 5-10, occasionally more numerous or reduced to a single fertile stamen; filaments usually glabrous, usually distinct; pollen grains usually tricolporate or triporate. Carpels typically 3, sometimes 5, variously connate; ovary usually superior, sometimes all carpels fertile and gynoecium multilocular with axile placentation, more commonly only 1 carpel fully developed and fertile (and others typically represented merely by their styles) and gynoecium asymmetrical and unilocular with apical placentation; stugmas usually capitate. Ovules 1 in each locule, or in 1 in the single fertile carpel. Nectar disk present, intrastaminal. Fruit an often flattened asymmetrical drup; embryo curved to straight; endosperm scanty to lacking (figure 8.99)

Floral Formula:
Staminate: *, 5, 5-10,3(-5)•

Carpellate: *,5, 5-10•, 3(-5);drupe

Distribution: Mainly tropical, with a few species in temperate regions.

Genera/Species: 70/600. Major Genera: Rhus (100 spp.), Semecarpus (50), Lannea (40), Toxicodendron (30), Schinus (30), and Mangifera (30). Noteworthy genera of the continental United States and/or Canada include Cotinus, Metopium, Rhus, Schinus, and Toxicondendron.

Economic plants and products: Fruits of Mangifera indica (mango) and Spondias (mombin, hog plum) are eaten, as are the roasted seeds of Anacardium occidentale (cashew) and Pistacia vera (pistachio). Fruits of several species of Rhus are used in drinks. A black liquer is obtained from Toxicondendron vernicifluum (varnish tree). A few are ornamentals, including Cotinus (smoke tree), Rhus (sumac), and Schinus (Brazilian poepper). Finally, the group is of medical signifiance because of so many of its taxa, particularly Toxicodendron (poison ivy, poison oak, poison sumac) and Metopium

(poisonwood), promote dermititis in susceptible individuals due to the phenolic compound 3-n-pentadecycatehol in the resin. It is worth noting
that mangoes and cashews, even though edible, may still cause an allergic reaction.

Discussion: Anacardiaceae and Burseraceae both have resin canals, biflavones, and clearly form a clade based on their rbcL nucleotide sequences (Gadek et al. 1996). Anacardiaceae are tentatively considered to be monophyletic on the bassis of a reduced number of ovules, other morphological features, and rbcL sequences (gadek et al. 1996; Terrazas and Chase 1996), although the recognition of Burseraceae may make Anacardiaceae paraphyletic.

The family is composed of two major subclades Spondiadae, which have retained many pleisomorphic features such as gynoecia with usually five carpels, multiloculelar ovaries, and fruits with thick endocarp usually composed of lignified and irregularly oriented sclerids, may form a clad based on their septate fibers (Terrazas and Chase 1990, 1991). The remaining genera of the family form alarge clade, clearly supported by gynoeci with three or fewer) carpels, unilocular ovaries with apical plancentation, and fruits with an endocarp that is composed of discrete and regularly arranged layers of cells. Rhus and Toxicodendron have often been confused, and some botanists have united these two genera (and several others) Fruits of Rhus are gladular-pubescent and red, while those of Toxicondendron are glabrous and greenish to white. In addition, the resins of Rhus are not poisonous while those of Toxicondendron cause a "poison ivy" rash. If combined, the resulting group would not be monophyletic. The small, nectar-secreting flowers of Anacardiaceae are pollinated by various insects. Outcrosing is promoted by the more or less dioecious condition of members of this family. The large to small drupes are dispersed by various birds or mammels (including bats).

References:
Brizicky 1962a; Cronquist 1981; Gadek et al. 1996; Gillis 1971; Terrazas and Chase 1996; Wannan and Quinn 1990, 1991.