The tea leaf is the young shoot of Camellia sinensis, an evergreen shrub whose tender leaves and unopened bud are the single raw material behind every true tea. Picked as the soft new growth at the tip of a branch, the same leaf becomes green, white, oolong, black or pu-erh tea depending entirely on how it is afterwards withered, bruised, oxidised and dried — and, ground whole, becomes matcha. Fresh, the leaf is glossy, leathery and faintly grassy; dried and processed it concentrates the bitterness and astringency of its catechins, the savoury sweetness of the amino acid L-theanine and a dose of caffeine. It is not usually eaten as a vegetable but steeped, so the world drinks the leaf rather than chewing it.