Cashew
Anacardium occidentale
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The Cashew (Anacardium occidentale) is a tropical evergreen tree in the family Anacardiaceae, renowned for its distinctive kidney-shaped nut and the fleshy, pear-shaped accessory fruit (cashew apple) to which it is attached. Native to northeastern Brazil, the cashew is now widely cultivated throughout tropical regions for its nuts, which are a globally significant commercial crop. The tree is a resilient, multipurpose plant, providing food, medicine, and industrial raw materials.
Taxonomy
Kingdom
Plantae
Phylum
Tracheophyta
Class
Magnoliopsida
Order
Sapindales
Family
Anacardiaceae
Genus
Anacardium
Species
Anacardium occidentale
The cashew tree is native to the coastal regions of northeastern Brazil. Its domestication and dispersal are closely tied to human history.
• Indigenous peoples of Brazil, such as the Tupi, utilized the cashew long before European contact, calling it 'acaju' (meaning 'nut that produces itself').
• Portuguese explorers introduced the tree to other tropical regions in the 16th century, initially to India and Mozambique, to control coastal erosion and later for its commercial value.
• From India, it spread throughout Southeast Asia and eventually to West Africa.
• Today, major producers include Vietnam, India, Côte d'Ivoire, and Brazil.
• Indigenous peoples of Brazil, such as the Tupi, utilized the cashew long before European contact, calling it 'acaju' (meaning 'nut that produces itself').
• Portuguese explorers introduced the tree to other tropical regions in the 16th century, initially to India and Mozambique, to control coastal erosion and later for its commercial value.
• From India, it spread throughout Southeast Asia and eventually to West Africa.
• Today, major producers include Vietnam, India, Côte d'Ivoire, and Brazil.
The cashew tree is a spreading, evergreen perennial that typically reaches a height of 10–14 meters, though dwarf cultivars (around 6 meters) exist for commercial production.
Trunk & Canopy:
• The trunk is often gnarled and irregular, branching low to the ground.
• The canopy is dense and broadly spreading, providing significant shade.
Leaves:
• Simple, alternate, obovate to oblong, 10–20 cm long and 5–10 cm wide.
• Leathery texture with prominent veins and a smooth margin.
Inflorescence & Flowers:
• Borne in terminal panicles, 10–20 cm long.
• Flowers are small, 5–8 mm in diameter, and fragrant, with five pale green to reddish petals.
• The species is andromonoecious, meaning each panicle contains both male (staminate) and bisexual (perfect) flowers.
Fruit (Drupe & Accessory Fruit):
The cashew produces a unique two-part structure:
• The Cashew Apple: A fleshy, swollen pedicel (false fruit or accessory fruit), pear-shaped, 5–11 cm long, with waxy yellow, orange, or red skin. It is juicy, fibrous, and highly perishable.
• The Cashew Nut: The true fruit, a kidney-shaped drupe about 3 cm long, attached to the apex of the cashew apple. Its hard, double-layered shell contains a single edible kernel.
Trunk & Canopy:
• The trunk is often gnarled and irregular, branching low to the ground.
• The canopy is dense and broadly spreading, providing significant shade.
Leaves:
• Simple, alternate, obovate to oblong, 10–20 cm long and 5–10 cm wide.
• Leathery texture with prominent veins and a smooth margin.
Inflorescence & Flowers:
• Borne in terminal panicles, 10–20 cm long.
• Flowers are small, 5–8 mm in diameter, and fragrant, with five pale green to reddish petals.
• The species is andromonoecious, meaning each panicle contains both male (staminate) and bisexual (perfect) flowers.
Fruit (Drupe & Accessory Fruit):
The cashew produces a unique two-part structure:
• The Cashew Apple: A fleshy, swollen pedicel (false fruit or accessory fruit), pear-shaped, 5–11 cm long, with waxy yellow, orange, or red skin. It is juicy, fibrous, and highly perishable.
• The Cashew Nut: The true fruit, a kidney-shaped drupe about 3 cm long, attached to the apex of the cashew apple. Its hard, double-layered shell contains a single edible kernel.
Cashew trees are hardy and well-adapted to tropical lowlands, often thriving in marginal soils where other crops struggle.
Climate & Soil:
• Optimal growth occurs in hot, humid tropical climates with a distinct dry season.
• Annual rainfall between 1,000 and 3,500 mm is suitable, but the tree is highly drought-tolerant.
• It shows a strong preference for well-drained, deep, sandy or loamy soils. It does not tolerate waterlogging.
• Saline and poor lateritic soils can also support cashew growth, making it valuable for land rehabilitation.
Pollination:
• Flowers are primarily insect-pollinated, attracting bees, flies, and ants.
• Both self- and cross-pollination occur, but cross-pollination typically results in higher fruit set.
Ecological Role:
• The extensive root system helps prevent soil erosion, a key reason for its initial introduction to coastal India and Africa.
Climate & Soil:
• Optimal growth occurs in hot, humid tropical climates with a distinct dry season.
• Annual rainfall between 1,000 and 3,500 mm is suitable, but the tree is highly drought-tolerant.
• It shows a strong preference for well-drained, deep, sandy or loamy soils. It does not tolerate waterlogging.
• Saline and poor lateritic soils can also support cashew growth, making it valuable for land rehabilitation.
Pollination:
• Flowers are primarily insect-pollinated, attracting bees, flies, and ants.
• Both self- and cross-pollination occur, but cross-pollination typically results in higher fruit set.
Ecological Role:
• The extensive root system helps prevent soil erosion, a key reason for its initial introduction to coastal India and Africa.
The cashew nut and cashew apple have distinct nutritional profiles.
Cashew Nut (per 100g, raw):
• Energy: ~553 kcal
• Total Fat: ~44 g (of which saturated fat is ~8 g, monounsaturated fat is ~24 g)
• Carbohydrates: ~30 g
• Dietary Fiber: ~3.3 g
• Protein: ~18 g
• Vitamins and Minerals: Rich in copper (~2.2 mg, >100% DV), manganese, magnesium, phosphorus, and vitamin K.
Cashew Apple:
• The cashew apple is rich in vitamin C, containing up to 5 times the concentration found in an orange (around 200–260 mg per 100g of fresh weight).
• It also contains significant amounts of antioxidants, including polyphenols and carotenoids.
• The high tannin content gives the raw fruit an astringent, puckery mouthfeel.
Cashew Nut (per 100g, raw):
• Energy: ~553 kcal
• Total Fat: ~44 g (of which saturated fat is ~8 g, monounsaturated fat is ~24 g)
• Carbohydrates: ~30 g
• Dietary Fiber: ~3.3 g
• Protein: ~18 g
• Vitamins and Minerals: Rich in copper (~2.2 mg, >100% DV), manganese, magnesium, phosphorus, and vitamin K.
Cashew Apple:
• The cashew apple is rich in vitamin C, containing up to 5 times the concentration found in an orange (around 200–260 mg per 100g of fresh weight).
• It also contains significant amounts of antioxidants, including polyphenols and carotenoids.
• The high tannin content gives the raw fruit an astringent, puckery mouthfeel.
The cashew nut shell contains a potent, caustic resin that poses a significant health hazard.
• Shell Liquid (CNSL): The shell contains cashew nut shell liquid (CNSL), which is rich in anacardic acid (structurally related to urushiol, the allergen in poison ivy).
• Effects: Direct contact with CNSL causes severe dermatitis, characterized by painful blistering and skin irritation. The fumes released during roasting are also highly irritating to the eyes and respiratory system.
• Processing: The 'raw' cashew nuts sold commercially are never truly raw. They have been processed by roasting, boiling, or steaming to destroy the toxic oil and make the shell brittle enough to crack safely.
• Shell Liquid (CNSL): The shell contains cashew nut shell liquid (CNSL), which is rich in anacardic acid (structurally related to urushiol, the allergen in poison ivy).
• Effects: Direct contact with CNSL causes severe dermatitis, characterized by painful blistering and skin irritation. The fumes released during roasting are also highly irritating to the eyes and respiratory system.
• Processing: The 'raw' cashew nuts sold commercially are never truly raw. They have been processed by roasting, boiling, or steaming to destroy the toxic oil and make the shell brittle enough to crack safely.
Cashew cultivation requires a long-term perspective, as trees are perennial and can bear fruit for decades.
Propagation:
• Seed Propagation: Seeds must be viable (sink in water) and are planted directly in the field or in polybags. They germinate within 1–3 weeks. Seedlings are typically grafted with scions from high-yielding varieties to ensure quality.
• Vegetative Propagation: Grafting, budding, and air-layering are common commercial methods to propagate superior cultivars and dwarf varieties.
Spacing & Planting:
• Standard spacing is 7 m x 7 m to 10 m x 10 m, allowing for the broad canopy.
• Planting is best done at the onset of the rainy season.
Pruning:
• Formative pruning in the first 2–3 years is essential to develop a strong, well-shaped framework.
• Regular removal of dead, diseased, or crossing branches maintains tree health and facilitates harvesting.
Pests & Diseases:
• Key pests include the cashew stem and root borer, tea mosquito bug, and thrips.
• Anthracnose (Colletotrichum gloeosporioides) is a major fungal disease affecting leaves, inflorescences, and young fruits, causing significant yield loss in humid conditions.
Propagation:
• Seed Propagation: Seeds must be viable (sink in water) and are planted directly in the field or in polybags. They germinate within 1–3 weeks. Seedlings are typically grafted with scions from high-yielding varieties to ensure quality.
• Vegetative Propagation: Grafting, budding, and air-layering are common commercial methods to propagate superior cultivars and dwarf varieties.
Spacing & Planting:
• Standard spacing is 7 m x 7 m to 10 m x 10 m, allowing for the broad canopy.
• Planting is best done at the onset of the rainy season.
Pruning:
• Formative pruning in the first 2–3 years is essential to develop a strong, well-shaped framework.
• Regular removal of dead, diseased, or crossing branches maintains tree health and facilitates harvesting.
Pests & Diseases:
• Key pests include the cashew stem and root borer, tea mosquito bug, and thrips.
• Anthracnose (Colletotrichum gloeosporioides) is a major fungal disease affecting leaves, inflorescences, and young fruits, causing significant yield loss in humid conditions.
The cashew tree is a classic example of a multi-purpose crop with uses spanning food, industry, and traditional medicine.
Food Uses:
• Kernel: Consumed as a roasted and salted snack, and used extensively in confectionery, baking, and as a base for vegan dairy alternatives (milks, cheeses, creams).
• Cashew Apple: Processed into refreshing juices, syrups, jams, chutneys, and alcoholic beverages like cashew feni (a specialty of Goa, India) and cashew wine.
Industrial Uses:
• Cashew Nut Shell Liquid (CNSL): A valuable byproduct used in the manufacture of brake linings, clutches, varnishes, paints, epoxy resins, and industrial laminates.
• The shell residue after CNSL extraction is used as fuel.
Traditional Medicine:
• Various parts of the tree are used in traditional medicine systems across the tropics.
• Cashew apple juice is used as a remedy for scurvy due to its high vitamin C content.
• Leaf and bark extracts are utilized for their antimicrobial, anti-inflammatory, and astringent properties to treat ailments like toothaches, sore throats, and dysentery.
Food Uses:
• Kernel: Consumed as a roasted and salted snack, and used extensively in confectionery, baking, and as a base for vegan dairy alternatives (milks, cheeses, creams).
• Cashew Apple: Processed into refreshing juices, syrups, jams, chutneys, and alcoholic beverages like cashew feni (a specialty of Goa, India) and cashew wine.
Industrial Uses:
• Cashew Nut Shell Liquid (CNSL): A valuable byproduct used in the manufacture of brake linings, clutches, varnishes, paints, epoxy resins, and industrial laminates.
• The shell residue after CNSL extraction is used as fuel.
Traditional Medicine:
• Various parts of the tree are used in traditional medicine systems across the tropics.
• Cashew apple juice is used as a remedy for scurvy due to its high vitamin C content.
• Leaf and bark extracts are utilized for their antimicrobial, anti-inflammatory, and astringent properties to treat ailments like toothaches, sore throats, and dysentery.
Fun Fact
A cashew apple is not a true fruit but a swollen flower stalk (pedicel), making the cashew nut the actual fruit. The nut's dangerous shell contains a resin so chemically aggressive that it is used industrially to make brake fluid and anti-termite treatments for wood. The reason cashew nuts are never sold in their shell, unlike almonds or walnuts, is precisely because of this toxic, blistering liquid that must be carefully removed through a process of high-heat roasting, which makes the nut safe to eat.
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