Hour zero: the shoot is not yet anything
A basket of freshly plucked shoots is not green tea material or black tea material. It is tea leaf, and it could still become any of the six categories. What has already been decided is the ceiling: how much of the shoot was taken, how uniform the intake is, and whether it heated in the sack on the way in. None of those decides the category and all of them decide how good the result can be. The first genuinely irreversible decision is not a processing step at all — it is how long the leaf sits before anything happens to it, and in what conditions. Leaf packed deep and left warm has already begun changing in a way nobody chose. So the tree begins before the first fork, with a step that most accounts skip: the leaf has to be got to the factory in a condition that still permits a choice.
Fork one: heat now, or let the leaf change first?
This is the fork with the largest consequences and it is taken within hours. Heat the leaf now — steam it or put it in a hot pan — and the enzymes are gone, the leaf will stay green, and the tea will be a green tea, a yellow tea if you insert a smothering step later, or a sheng pu-erh if you run the heat cool and then dry the leaf in the sun rather than an oven. Do not heat it, and it will change on its own, and you are now in the other half of the tree: black tea, oolong, or white tea. Notice what this fork does not decide. It does not decide the shape, the roast, whether the tea is scented, or whether it will be pressed into a cake. It decides only whether the leaf's own enzymes get to act, and everything downstream is arranged around that one answer.
Fork two, on the unheated branch: rupture everywhere, at the edges, or not at all?
Nothing oxidises until cells rupture, because the enzymes and the compounds they act on are held apart inside intact tissue. So the second fork on this branch is about damage. Rupture the leaf comprehensively — twist it on a rolling table, or cut it between toothed rollers — and oxidation runs through the whole leaf: that is black tea, orthodox if twisted and CTC if cut. Rupture it only at the margins by shaking it, over and over, with long rests in between, and oxidation happens at the rim while the centre stays green: that is oolong, and a finished oolong leaf held to the light shows exactly that. Do not rupture it at all, and the leaf oxidises slowly and incompletely wherever it has damaged itself: that is white tea, which is why it is described as unoxidised and as lightly oxidised by different writers who are both partly right.
Fork three, on the oolong branch: when do you stop?
The oolong branch is the only one where the maker chooses the moment rather than following a schedule, and it is why oolong is the hardest of the six to make and the widest in character. After each shake the leaf is laid out and left completely still for anything from half an hour to two hours, and during that stillness the bruised edges brown and the aroma of the whole bed moves — grassy, then green-floral, then orchid, then honeyed and fruity. The maker decides when to apply heat by smelling it. Stop early and you have a pale, floral, high-aromatic tea; stop late and you have an amber, honeyed one; and both were the same leaf on the same night. Two further forks hang off this one. The shaping fork — compact the leaf into a hard pellet or twist it into a loose strip — decides how the tea behaves in water for the rest of its life. And the roasting fork decides whether the tea is finished in a week or over the following year, because a roasted oolong is roasted, rested for months, tasted, and roasted again.
Fork four, on the heated branch: what kind of drying, and is anything inserted?
Back on the branch where heat came first. Two questions remain and they are both quiet ones. First: is anything inserted between the fixation and the finish? Wrap the still-warm, still-damp leaf and leave it, and it turns yellow-olive and grain-sweet, and you have made yellow tea — the only category in the six created by an addition rather than a substitution or a reordering. Second: how is it dried? An oven takes the leaf to storage dryness and effectively finishes it, and you have a green tea that is best in its first year. Dry it slowly in the sun instead, at low temperature, and the leaf is not finished: it keeps residual capacity to change, and what you have made is pu-erh maocha, which will be compressed and stored and will be at its worst in its first year. One substitution, at the drying slot, and the tea's entire relationship with time inverts.
Fork five: is the tea finished, or is it an ingredient?
The last fork acts on a tea that is already made, and it is the one that makes the six-category scheme creak. Roast a finished sencha hard enough and it becomes hojicha, which is a different drink sold under a different name and is still, on any strict reading, a green tea. Layer a finished green tea with fresh jasmine overnight, screen the spent flowers out, re-dry it, and do that up to nine times, and you have jasmine tea. Wet a finished sun-dried maocha, heap it and let a mixed population of moulds and bacteria work through it for weeks, and you have shou pu-erh. Press a finished dark tea into a brick and cultivate a single fungus inside it, and you have a Fu brick. All four begin with a complete, saleable tea. The categories classify a defining step, not a full history, and several teas have more history than the scheme can express — which is a limitation of the scheme rather than of the teas.