The Botanical Classification: Drupe Seed vs. True Nut
Botanically, a true nut is a dry, hard-shelled fruit containing a seed that doesn't open on its own, like acorns or hazelnuts. Cashews do not fit this definition; they are classified as drupe seeds. Drupes are fruits with a fleshy exterior and a hard inner layer (endocarp) enclosing a seed, such as peaches or plums. Cashews, along with almonds and walnuts, are considered drupe seeds where we consume the seed. The cashew grows uniquely, with the seed encased in a kidney-shaped drupe that protrudes from a structure called the cashew apple, which is actually a swollen stem. This growth pattern distinguishes it from a true nut.
Other Common "Nuts" that Aren't Nuts
- Almonds: These are seeds within a drupe fruit.
- Walnuts & Pecans: Also drupes, the part we eat is the seed.
- Peanuts: These are legumes, related to peas and beans, growing in pods underground.
The Culinary Context: Why We Call Them Nuts
Despite their botanical reality, cashews are grouped with nuts in cooking because of their similar taste, texture, and nutritional value. They are often used interchangeably in recipes and are a good source of healthy fats, protein, and minerals.
Botanical Comparison: True Nuts vs. Drupe Seeds vs. Legumes
| Feature | True Nut | Drupe Seed (e.g., Cashew) | Legume (e.g., Peanut) |
|---|---|---|---|
| Botanical Class | Dry, indehiscent fruit | Single seed from a fleshy fruit | Edible seeds within a pod |
| Edible Part | Fruit and seed in one unit | The seed within a stony pit | The seeds within a pod |
| Shell Type | A hard shell that does not open | A hard shell (endocarp) covering the seed | A pod that splits open to release seeds |
| Growth Location | Typically grows on a tree | Grows on a tree (hanging from a pseudofruit) | Grows in a pod, often underground |
| Examples | Acorns, hazelnuts, chestnuts | Cashews, almonds, walnuts | Peanuts, peas, beans |
The Journey from Tree to Safe Snack
The cashew's shell contains urushiol, a toxic resin also found in poison ivy. This requires cashews to be heated (roasted or steamed) to remove the toxin before they are safe to eat. This is why truly raw cashews are not sold and even those labeled “raw” have undergone heat processing. The toxic oil also has various industrial uses.
The Versatile Cashew Apple
The cashew apple, the fleshy part the cashew nut hangs from, is a valuable but less-exported part of the cashew plant. Rich in Vitamin C, it is consumed fresh, as juice, or fermented into drinks in tropical regions. Its delicate nature limits its availability elsewhere.
Health and Nutritional Benefits
Cashews are very nutritious, offering healthy fats, protein, fiber, and minerals like magnesium, phosphorus, and copper. They are linked to benefits for heart health, blood sugar, and energy. Magnesium is also important for sleep and bone health.
Conclusion: A Seed of Distinction
In summary, why are cashews not considered a nut? Their botanical classification as a seed of a drupe fruit and their specific growth and processing requirements distinguish them from true nuts, even though we use them like nuts in food. Their unique characteristics only add to the appeal of this popular and nutritious snack. For detailed nutritional information, resources like Healthline are available.
Keypoints:
- Botanical Identity: Cashews are not true nuts but are botanically classified as drupe seeds.
- Unique Growth: The edible cashew seed grows inside a kidney-shaped drupe, which hangs from the end of a fleshy pseudofruit called the cashew apple.
- Toxic Shell: The outer shell of the cashew contains a toxic resin, urushiol, requiring careful heat processing before consumption.
- Culinary Classification: Despite botanical facts, cashews are treated as nuts in cooking due to their flavor, texture, and nutritional similarities.
- Processing Safety: The heat treatment of cashews makes them safe to eat, eliminating the risk of exposure to the urushiol in their shell.
FAQs
Q: What is a drupe? A: A drupe is a type of fruit with a fleshy exterior and a hard stone or pit inside that contains a single seed. Examples include peaches, olives, and mangoes, as well as cashews, almonds, and walnuts.
Q: How are cashews harvested and processed? A: Cashews are harvested from tropical trees, and the nuts are separated from the cashew apples. They are then steamed or roasted to neutralize the toxic urushiol in their shells before being cracked open and packaged for sale.
Q: Are peanuts botanically true nuts? A: No, peanuts are legumes, which are part of the pea and bean family. Unlike nuts that grow on trees, peanuts grow in pods underground.
Q: Can you get a rash from a cashew? A: Not from a properly processed cashew. However, the raw shells contain a potent irritant called urushiol, the same substance found in poison ivy. This is why you should never try to open a raw cashew from a tree.
Q: Is the cashew apple edible? A: Yes, the fleshy cashew apple is edible. It is rich in vitamin C and used in juices, jams, and other products in the regions where it grows, though its short shelf life makes it uncommon elsewhere.
Q: Are cashews and mangos related? A: Yes, the cashew tree belongs to the Anacardiaceae family, which also includes mangos, as well as pistachios and poison ivy.
Q: Why are store-bought “raw” cashews safe to eat? A: Even “raw” cashews have been heat-treated (steamed or roasted) to destroy the toxic urushiol in their shells. The term “raw” simply means they haven’t been roasted or salted after this initial processing.
