She was born in TA 2904 (SR 1304) to Mirabella Took and Gorbadoc Brandybuck. Amaranth's older brother, Rory, was the grandfather of Meriadoc Brandybuck. She also had five younger siblings, one of which, Primula, was the mother of Frodo Baggins. Amaranth Brandybuck died in TA 2998 (SR 1398).
An Amaranth is a poetic term for a flower that never withers. It is also the name of a short-lived herb, found mostly in temperate and tropical regions.