Pistachios: Are they nuts or fruits?
If you were asked to name a few nuts, the first ones that will come to your mind would most likely be pistachios, cashews and almonds. Right? But technically, your answer would be wrong. Why? Because these are not nuts. Rather these are drupes. True nuts are acorns, chestnuts, and hazelnuts.
What is a nut?
In botanical terms, a nut is a dry fruit with a hard inedible shell, covering a single seed. For example, some true nuts are acorns, chestnuts, and hazelnuts. If you all try and apply the definition above to these three, they fit perfectly. They have a hard shell that cannot be eaten and they have a single seed inside. This shell does not open by itself to release the seed. What we consume is this seed.
Pistachios are actually drupes
Now think of pistachios. The hard shell that you see outside is actually a dried fruit and not an inedible shell. The pistachio trees develop grape-like clusters of green-coloured wrinkled fruits. The husked fruit contains a thin, ivory-coloured, bony shell that splits longitudinally along its sutures when mature. Inside this shell is the kernel or the seed. This is what is ‘mistakenly’ referred to as the nut. The kernel ranges in colour from yellowish to bright green, the more prized specimens being the more vibrantly hued. These husked fruits are picked, hulled, dried, and often roasted before being sold in the market. Therefore, pistachios fall into the category of ‘drupes’.
What are drupes?
So technically, drupes are fruits that are fleshy on the outside and have a shell covering as well as a seed on the inside. In the case of pistachios, we discard their fruit flesh and consume the tasty seed which is inside. The same goes for the fruits of the cashew and almond plants. Since they are the seed covered by a fleshy fruit, they are not true botanical nuts.
What about walnuts? Well, it is still not very clear — they have characteristics of both nuts and drupes, but don’t completely fulfill the criteria for either. They are often referred to as “nut-like drupes” or “drupaceous nuts”.
But how did we get it so wrong? Well, it is not your fault. As a consumer, you would consider what's on the grocery shelf. If a woody shell-encased food is small, roundish, natural, dry and crunchy, you are likely to call it a nut. But a botanist considers the whole plant.
Origin of pistachios
The pistachio is native to Western Asia and the Middle East. Historical evidence indicates that they have been around for over 8,000 years. Who produces the most pistachios in the world today? Since they grow well in dry climates, you will find their maximum production in Iran, few parts of the US, and Mediterranean countries.