The cashew tree (Anacardium occidentale) is a tropical evergreen species native to northeastern Brazil. Its cultivation has since spread across tropical climates worldwide. The tree is known for its complex structure and adaptability, thriving in warm, often dry, environments.
General Appearance and Vegetative Structure
The cashew tree is typically a medium-sized plant, reaching heights between 8 and 14 meters in mature specimens, though dwarf cultivars exist for commercial farming. It possesses a short, often irregularly shaped trunk that branches low to the ground. This contributes to a wide, dense, and often asymmetrical canopy that can spread up to 12 meters in diameter. The bark is rough and somewhat fissured, appearing light gray or brown, and it contains a resinous sap.
The leaves are large, simple, and alternate, clustering near the ends of the branches. They exhibit a leathery texture and an obovate shape, meaning they are wider toward the rounded tip. Mature foliage is a deep, glossy dark green. New growth often displays a pale green or reddish-bronze color before transitioning. Leaves typically range from 10 to 22 centimeters in length and 4 to 15 centimeters in width.
The Cashew Tree’s Flowering Process
The tree’s reproductive cycle begins with terminal inflorescences, which are large, branching clusters of flowers called panicles. These panicles emerge at the tips of the branches and measure between 10 and 26 centimeters long. They contain hundreds of tiny, individual flowers, each measuring less than a centimeter in diameter.
The flowers have five slender petals that are initially pale green, transitioning to a yellowish or reddish tint as they mature. The panicles contain both male and hermaphroditic flowers, an arrangement known as andromonoecy. A mild, sweet fragrance attracts insects like bees and flies that facilitate pollination.
The Distinctive Cashew Fruit Complex
The cashew tree’s fruit complex consists of two distinct parts. Botanically, the true fruit is the kidney-shaped structure that hangs suspended below a much larger, fleshy body. This true fruit is a drupe, often referred to as the cashew nut, and it contains the single, edible seed within a hard shell.
Attached directly above the true fruit is the vibrant, fleshy, pear-shaped structure known as the cashew apple. This is not a true fruit but an accessory fruit, or hypocarp, which develops from the swollen pedicel and receptacle of the cashew flower. The true fruit develops first, and then the stalk tissue rapidly expands to form the apple.
The cashew apple is soft, juicy, and thin-skinned, ripening into shades of yellow, orange, or red. It measures between 5 and 11 centimeters in length and is highly perishable once harvested. The attachment of the nut, positioned outside and below the fleshy apple, creates a highly unusual appearance that distinguishes the cashew tree. The shell of the raw nut is gray-brown and contains a caustic resin called cashew nut shell liquid, which requires careful processing before consumption.