Nut is a simple enough word, yet it has many meanings. Nut is the name of the ancient Egyptian goddess of the sky, a hardware fastening device, “nuts and bolts”, a piece of metal wedged into rocks for protection by rock climbers and a source of food.
Even that’s not enough meanings for a simple three letter word. If we look more closely at how we define a nut in the food sense, more definitions start to appear!
What is a nut?
The botanical definition of a nut in its simplest form is a seed contained within a hard shell, which is indehiscent – it does not naturally open to release the seed on maturity.
The culinary definition of a nut is much more obliging and incorporates a whole range of edible plant parts. It is often considered to be any edible kernel surrounded by a shell.
Seeds that are commonly through of as nuts
Despite nut being in the name, peanuts are not nuts, at least not in the botanical sense. The peanut grows underground, in a pod like peas and lentils. This means it is not classified as a nut but rather as a legume, which is reflected in the “pea” part of the name.
The cashew nut grows on the cashew tree, which goes to extraordinary lengths to prevent it from being eaten. Cashew nuts grow at the bottom of the cashew apple in a pod filled with an acidic liquid which will burn any unsuspecting grazer. This extreme method is employed by the tree to protect its seed – the cashew.
The botanical definition for nut means many foods we call nuts are not nuts, but in fact seeds. Almonds, Brazil nuts, cashews, macadamias, pecans, pistachios, pine nuts and walnuts all fall into this trap. The term tree nut is often used to cover this group of seeds we so instinctively think of as nuts.
What is a seed?
A seed is a mature fertilised ovule of a plant, consisting of three parts: the embryo, a food store and a protective coating. A seed may also go by the name of kernel, pip, pit or stone depending on its source.
A nut can also be a seed but a seed by definition is not a nut.
Nuts that are commonly thought of as seeds
Two common trees in the UK produce nuts which masquerade as seeds: hornbeam and beech.
One of the most common nuts to be mistaken for a seed is beech mast. When mature, beech trees have mast years every two to three years, when they produce a bonanza of nuts.
The UK National Tree Seed Project faces many challenges in order to collect and store seeds. We have even collected a few of the sneaky nuts posing as seeds from beech trees. Our work is not finished though and some help with a few seed collections left to make this year would be greatly appreciated. You don’t have to be an expert on seeds and nuts, but you do need to know your trees.