Spices are plant parts that are more densely loaded with flavour than most other ingredients used in cooking. Whereas herbs always come from leafy parts, spices tend to derive from seeds, fruits, roots, stems, flowers, or bark, and are usually dried. That said, some strongly flavoured leaves, such as bay and curry leaf, can be considered spices because they are used more as a potent background flavouring than as a fresh addition.
Spices have been valued throughout history, in religious ceremonies and medicine as much as in cooking. Science has shown us that these once-mystical plant parts are in fact the vessels of chemicals known as flavour (or aroma) compounds, generated to help plants survive and reproduce, performing roles such as repelling animals or protecting against bacteria. By happy coincidence, many of these compounds have aromas that are pleasant to humans.
The stem of a plant distributes water and sugars to where they are needed. Few spices derive from stems: lemongrass is the stalk of a tropical grass and little-known mastic is the dried resin collected from lentisk trees; more famously, cinnamon and cassia are dried pieces of inner and outer bark, respectively, of Cinnamomum trees.
Roots And Underground Stores
Roots are a plant’s lifeline to water and nutrients, and rhizomes, corms, and bulbs are storage chambers with the ability to produce new shoots and roots. Liquorice comes from dried roots and asafoetida is derived from dried root sap. Turmeric, ginger, galangal, and garlic are all examples of underground stores
The seeds of flowering plants are contained in fruits. Many have evolved to be sugar-rich so that they make an appealing meal for animals, who thereby distribute the seeds over a wide area. Numerous spices are derived from fruits, including allspice, sumac, vanilla, and chillies. Several “seed” spices are technically fruits, including dill and ajwain.
The majority of spices are seeds; think of cumin, cardamom, mustard, and fenugreek, or less obviously nutmeg, which is a seed kernel. It is little wonder that plants frequently concentrate their strongest-tasting defensive chemicals in seeds, since these are the precious packets of new life that will sprout into the next generation of plants.
Many flowers are known for their attractive aromas, which have evolved to entice insects into paying a visit and pollinating the flower as they do so. Only a few have strong enough appealing flavours to be considered a spice, most famously saffron, whose red strands are pollen-receiving female sex parts (stigmas) of a crocus flower. Another notable flower spice, it may be surprising to discover, is clove.