When tea is harvested, different parts of the plant are plucked, depending on the quality of the tea to be produced, the type of tea, the country etc. Tea picking is an important stage in tea processing and historically much has been written about the activity and the women who carried it out. Chatterjee (reference below) for example, mentions one account of labour management in the Tang Dynasty where tea pickers were required to abstain from eathing fish and certain kinds of meat so that their breath might not affect the bouquet of the leaves. He also talks about how women’s hands and fingernails were inspected to ensure body oils and perspiration would not contaminate the leaves.
Today, it is generally accepted that for high quality orthodox tea, the leaves at the tip of the stem are hand-picked. Plucking the bud and adjacent leaves encourages new shoots to grow. Dexterity and speed are required, as the pickers snap the top, tender stems using the index finger and thumb and breaking the leaves off with a quick snap although many farmers have adopted the time-saving method of attaching a blade to the index finger for snipping the stem.
The tender leaves at the top of the plant are the freshest growth and the most tender and are the richest in catechins and theanine. Imperial plucking involves just the bud and one leaf. Fine plucking takes the bud and the two adjacent leaves at the top of the plant stem. Average plucking takes the bud and three leaves.
Below are two photos of a jasmine pearl tea. The photo on the left is before steeping and the one on the right is the unfurled leaf after steeping. The beauty and perfection of the unfurled bud with its adjacent leaf or two leaves strikes me every time I make this tea.