Tea began as a medicine and grew into a beverage. In China, in the eighth century, it entered the realm of poetry as one of the polite amusements. The fifteenth century saw Japan ennoble it into a religion of aestheticism Teaism. (Kakuzo Okakura, The Book of Tea)

So what exactly is this drink that has been so highly revered for centuries by those on the path to enlightenment, that has been fought over in wars and used to commit great treachery, that defines nations in its very preparation, and commands such ceremony and ritual across the World?

Tea refers to the leaves or the infusion made with the leaves of the Camellia Sinensis plant.

Many people are surprised to find that all tea – be it white, green, oolong, black or pu-erh – come from the one plant family, the Camellia Sinensis.

Yes. All the same plant family. Much of what makes a green tea green, a black tea black etc is in the processing.

Strictly speaking, the leaves from a single bush harvested on any given day could be used to create white, green, oolong, black or pu-erh tea. In reality it doesn't happen like that because tea growing and tea making are very specialised activities.

Without getting too technical, there are two main subvarieties of Camellia Sinensis used to make tea – one is Sinensis (native to China) and the other Assamica (native to the Assam region in India – although ancient tea trees of the Assamica variety can be found in Yunnan, China).

Within these two subvarieties there are many different varietals and cultivars, and these contribute to the enormous diversity in the world of tea.

What about Herbal 'Teas'?

It might be a good place to make a distinction between tea and what we often refer to as herbal tea. Herbal teas are technically not 'teas', but can be made from many different kinds of botanicals. This should in no way detract from their status as a delicious beverage, and it is not a crime to call them 'teas' … but now you know.

You can demonstrate your knowledge of this point by using instead, the terms 'herbal infusion' or 'tisane'. Incidentally, a tea blended with botanicals (such as Soulful Sun or Mellow Mornings) can be referred to as a 'fusion'.

If all teas come from the Camellia Sinensis, what makes them different from one another?

Much of what makes the teas in each category different from each other is in the processing. The key aspect of processing that creates the difference is the level of 'oxidisation' of the tea leaves –also (somewhat incorrectly) referred to as 'fermentation'.*

What is oxidisation?

Oxidisation occurs when something is left exposed to the air and becomes brown – similar to what might happen to a piece of fruit left exposed to the air. If the fruit is cut open or damaged, it will brown more quickly. Although it might be less attractive to look at, generally it will become sweeter as a result of this process. This principle can be applied to some extent with teas.

Fruit becomes oxidised when exposed to the air

Teas can undergo oxidisation both naturally and intentionally in the tea factory.

White tea

White tea was most probably the first type of tea to be drunk thousands of years ago in China. It is produced with very little processing – it is essentially withered and left to dry, or dried using warm air. The leaves may undergo a small degree of oxidisation naturally while they are being dried. This is why some white teas like Pai Mu Tan consist of various coloured leaves – green, white and brown.

White teas like Pai Mu Tan can have varied leaf colour

Other white teas, such as Silver Needles consist of only the bud, or new growth of the tea leaf, and are more uniformed in colour and shape. This style of white tea typically has a very light and delicate flavour, while a white tea like Pai Mu Tan will generally be fuller flavoured.

Green tea

Green teas are unoxidised teas.

A High Mountain Green Tea stretching and breathing in water

Thinking back to the example of fruit that becomes brown when left to the open air, imagine instead that the fruit is baked soon after cutting it open (like the apple in an apple pie) – it remains white. That is because the baking at high temperature halts the natural oxidisation process. Green tea is like the apple in an apple pie.

Leaves are withered and then heat-treated so as to kill the enzymes in the plant that would lead to oxidisation. Chinese style green teas are pan-roasted, and Japanese style teas (like Sencha) are steamed.

There are many different styles of green tea, which undergo various processes of drying and shaping. In China, the shape or appearance of the leaves is often considered a 'trademark' of a particular region, achieved by artisan tea makers whose skills have been passed down to them from many previous generations.

For example Long Jing (Dragonwell) is one of the top 10 famous Chinese teas and is known for the distinctive shape of the leaves created by artisans in Zhejiang Province. It is said that it takes three years for an apprentice to master the 13 hand strokes to create this tea.

Oolong

Oolong teas are partially oxidised.

What they lack in appearance oolongs make up for in taste!

These are the most complex teas to make, and certainly the most diverse. Each different oolong has its own unique set of characteristics, not only in terms of terroir, plant variety and tea making style – but when you add varying combinations of oxidisation and roasting, you have an infinite spectrum of flavours that are as different from each other as they are from teas in all the other categories!

Oxidisation for oolongs may be as little as 10 per cent or as much as 90 per cent (depending on which country you're in and who you're asking).

Oolongs typically have more complex flavour profiles than teas in the other categories – they may be floral, fruity, 'rocky', biscuity or faintly sweet.  Oolongs are like the browned fruit – what they lack in appearance they surely make up for in taste!

Black tea

Black teas are 100 per cent oxidised teas.

The leaves are withered, then rolled and crushed to release enzymes, which turn black through oxidisation. They are then dried.

Black teas are referred to in China as 'red' teas. The Chinese began producing black tea mainly to supply the English market, and did not traditionally consume much of this category of tea themselves. When the English began cultivating tea in India and Sri Lanka, it was black tea that was produced in those countries.

Pu-erh

Pu-erh is tea that has been aged and fermented – that is, it is fermented in the true sense of the word (using microbes and multiflora), rather than simply oxidised.

Pu-erh is produced in the Yunnan province of China, typically using the larger leafed Assamica variety of Camellia Sinensis. Depending on the style of Pu-erh, it can be aged for as little as a few months or for many years. Small amounts of decades old Pu-erh tea can fetch many thousands of dollars.

Like other aged products, such as wine and cheese, good Pu-erh teas improve in taste and aroma (and increase in value) as they mature.  They are loved for their earthy and woodsy flavours and aromas.

Pu-erh tea

Although, tomes can, and indeed have, been written, this post was designed to be read over a single cup of tea. If you have any questions or comments, feel free to email anytime.

*Fermentation is an industry term, the use of which is strictly speaking incorrect. The only type of tea that is truly fermented is Pu-erh.