Types of Tea Explained: Black, Green, White, Oolong and Rooibos
Pick up five different boxes of tea and you'll find five different leaves inside: some dark and wiry, some pale and downy, some twisted into tight little balls. It looks like five different plants. It almost always isn't.
Quick answer: black, green, white and oolong tea all come from the same plant, Camellia sinensis. What separates them is how long the leaf is left to oxidise after picking, not where it was grown or how it's packaged. Rooibos and most "herbal teas" aren't tea at all botanically; they're infusions made from a different plant or from herbs, flowers and fruit, brewed the same way but classed separately by the UK Tea & Infusions Association.
It all starts with one plant
Camellia sinensis is the tea bush. According to the UK Tea & Infusions Association, there are roughly 1,500 cultivars of it grown across some three dozen countries, from China to Kenya to Argentina. Black, green, white and oolong all start as leaves picked from this same plant. The flavour, colour and name you end up with depend almost entirely on what happens to the leaf in the factory in the hours after it's plucked.
The single biggest variable is oxidation: a natural browning reaction that starts the moment a leaf is bruised or broken and its cell walls are exposed to air. Leave it to run its full course and you get black tea. Stop it almost immediately and you get green tea. Everything else sits somewhere in between.
How oxidation turns one leaf into four different teas
| Tea type | Oxidation | What happens to the leaf |
|---|---|---|
| White tea | Minimal to none | Young buds and leaves are simply withered and dried, with no rolling or bruising step to trigger oxidation. |
| Green tea | Stopped almost immediately | Fresh leaf is steamed or pan-fired within hours of picking, which destroys the enzyme responsible for browning. |
| Oolong tea | Partial (10% to almost 80%) | Leaf is bruised, then oxidised for a controlled period before firing; the exact time decides the style. |
| Black tea | Full | Leaf is rolled or cut to release its juices, then left to oxidise fully before drying. |
Those oxidation ranges come from the UK Tea & Infusions Association's own breakdown of tea processing, which also notes that English Breakfast and Earl Grey are both made from black tea leaves, just blended or flavoured differently (source).
Is oolong just a halfway point between green and black tea?
In terms of oxidation, yes, though "halfway" undersells the range. The UK Tea & Infusions Association describes oolong oxidation as ranging from 10% to almost 80%, which is why oolongs can taste wildly different from each other. A lightly oxidised oolong can be close to green tea in character: pale, floral, grassy. A darker oolong, oxidised much further, leans towards the toasted, fruitier notes you'd associate with black tea. It isn't a blend of the two; it's the same leaf, stopped at a different point along the same process.
Is rooibos actually tea?
Not in the strict sense. Rooibos comes from Aspalathus linearis, a South African shrub, not from Camellia sinensis. The UK Tea & Infusions Association is explicit about this: herbal and fruit infusions "do not originate from the tea plant", even though they're brewed the same way and often sold alongside it (source). The same goes for most things labelled "herbal tea", properly called a tisane: peppermint, chamomile, hibiscus and the rest are infusions of leaves, flowers, roots or fruit from a huge range of different plants, not variations on the tea bush.
One practical point worth knowing: because rooibos isn't from the tea plant, it's naturally free of the caffeine tea leaves contain, rather than having had it removed afterwards, and many other herbal infusions are the same (though not all: yerba mate, for example, does contain caffeine). The UK Tea & Infusions Association lists rooibos alongside chamomile and liquorice as naturally caffeine-free for this reason (source). That's a difference in origin, not a claim about what the drink does for you.
Where do chai and flavoured blends fit in?
Chai isn't its own oxidation category. It's typically a black tea base with added spices, brewed stronger and often with milk. Earl Grey is black tea with bergamot added. Fruit and herb blends that include a small amount of actual tea leaves sit in a similar place: the base determines the oxidation story, and everything added on top is flavouring rather than a different type of tea. If a pack doesn't list Camellia sinensis, black tea or green tea anywhere in the ingredients, it's almost certainly a pure herbal or fruit infusion rather than a flavoured tea.
Does the tea type change how you should brew it?
Generally, yes, though the details are worth a guide of their own rather than repeating here. As a rough shape: more delicate, less oxidised teas (white, green) tend to want cooler water and a shorter steep, while fully oxidised black tea and naturally robust infusions like rooibos can take boiling water and longer in the pot. Oolong sits in between, and exactly where depends on how oxidised that particular oolong is.
Choosing a tea type for the moment
Once you know what separates these categories, choosing gets easier. If you want something bold enough to take milk and stand up to a proper British breakfast, that's black tea territory: our classic teas collection is the obvious starting point. If you're after something lighter and greener for a slower afternoon, unoxidised green tea is built for that. And if you want the ritual of a warm cup in the evening without caffeine, rooibos covers that gap: ours sit in the caffeine-free rooibos collection.
None of this is about one type being "better" than another. It's about matching the processing style, and the flavour it produces, to what you actually want from the cup in front of you.
FAQ
What's the main difference between black tea and green tea?
Oxidation. Black tea leaves are left to oxidise fully before drying, which darkens them and deepens the flavour. Green tea leaves are steamed or pan-fired almost immediately after picking, which stops oxidation and keeps the leaf, and the flavour, lighter and greener.
Is oolong tea a mix of green and black tea?
No, it isn't blended from the two. Oolong is the same tea plant processed with partial oxidation, ranging from 10% to almost 80% depending on the style, which is why some oolongs taste closer to green tea and others closer to black.
Is rooibos tea actually tea?
Not botanically. Rooibos comes from Aspalathus linearis, a South African shrub, not from the tea plant Camellia sinensis. It's classed as a herbal infusion rather than tea, which is also why it's naturally caffeine-free.
Does chai count as its own type of tea?
Not in terms of processing. Chai is usually a black tea base with added spices such as ginger, cardamom or cinnamon, so it follows the same full-oxidation process as any other black tea before the spices are added.
Which tea type should I try if I want something light and fresh-tasting?
Green tea or white tea are the places to start, since both involve little or no oxidation and tend to taste lighter and grassier than black tea or rooibos. Which you prefer usually comes down to trying a cup of each.
Sources: UK Tea & Infusions Association, Types of Tea; UK Tea & Infusions Association, About Herbal Infusions; UK Tea & Infusions Association, FAQs About Infusions.