Distal:   At or close to the far end, as of a branch or stem.

Proximal:   At or close to the near end, as of a branch or stem.

In the image of Symphyotrichum racemosum below, the capitula placed at the tip of the branches or at the top of the stem, are said to be "distal".  Those located near the main stem itself or base of the stem are said to be "proximal".
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