Anacardium. (From Greek ana, up, and kardia, heart.) Anacardiaceae. Eight species of trees and shrubs. Leaves spiral or alternate, expistulate, entire; petiole simple. Inflorescence terminal or axillary, paniculate or corymbose; flowers unisexual or bisexual; calyx 5-lobed; petals 5, imbricate, puberulous; stamens 7-10, one or two longer and stouter than the others, filaments subulate, basally connate, glandular-pubescent; ovary superior, obovoid, glabrous, unicarpellate, uniovulate, rudimentary in male flowers; style filiform, stigma obscure. Fruit a drupe; receptacle or peduncle enlarged and fleshy. Tropical America, naturalised throughout the Tropics. Oil extracted from the nut is used in lubricants, and the wood yields a gum used in inks, dyes and varnishes. Z10.

Anacardium species are native to the American tropics, where temperatures rarely fall below 15ºC. It occurs on stony, sandy soils at about 600m. Anacardium occidentale, the cashew, has become widely naturalised through cultivation. Its swollen receptacle, the cashew apple, is also edible and is used in jams and jellies. Ths shell of cashews is poisonous in the same way as poison ivy; the toxin, sometimes used as a termite repellant, is destroyed on roasting. Anacardium species tolerate soils too low in fertility to support most other crops, and are sometimes used in erosion control, and as a support for cultivated vanilla. They accept a pH range of 4.5-6.5 and are drough resistant, surviving in areas with rainfall as low as 50-380mm, although requiring a range 500-900mm to fruit well. They crop from 4-5 years of age, requiring little in the way of aftercare. Anacardium is a tree for hot semi-arid, frost-free climates. It crops poorly in equable climates like that of southern Florida, but it makes a useful evergreen shade tree, and is an attractive ornamental when in fruit. It is sensitive to cold when young and in the continental US should be protected by hessian bark wrap.

The rarely grown caja-acu, Anacardium spruceanum, native to forests of northern Brazil and Venezuela is an attractive tree, the foliage showing little green, being rose-coloured above fading to white, and spangled with scarlet fruits. The ornamental value of these trees is outweighed by the presence of urushiols that cause severe dermatitis.

In temperate climates grow as a hot glasshouse specimen, minimum temperature 16-18ºC, with direct sunlight and low humidity in a low-fertility loam-based mix. Water by drenching thoroughly and allow to dry out moderately between waterings.

Propagate from seed which germinates in a month or less at 21ºC, or by air layering. Large cuttings of ripe shoots with their leaves intact will root in a sandy medium, in a closed case with bottom heat. Choice commercial varieties are propagated by shield budding, onto seed raised understock, sown in situ. Anacardium are susceptible to anthracnose fungus.

CASHEW; MARANON; ACAJOU. Tree to 12m, andromonoecious. Trunk rarely straight; bark smooth, brown. Leaves 4-22 x 2-15cm, obovate to broadly elliptic, coriaceous, glabrous; petiole 5-20mm. Inflorescence a panicle or corymb, to 26cm, pubescent; bracts ovate-oblong, 5-10mm; pedicel 2-5cm; calyx lobes unequal, to 5mm, ovate-lanceolate; petals 7-15mm, linear, pale green striped red, becoming entirely red. Fruit to 3 x 2cm, reniform, grey-brown; seed reniform. Flowering continuous. Tropical America, naturalised Malaysia.