The grapefruit (Citrus × paradisi) is a subtropical citrus tree known for its sour to semi-sweet fruit. Grapefruit is a hybrid originating in Barbados as an accidental cross between two introduced species, sweet orange (C. sinesis) and pomelo or shaddock (C. maxima), both of which were introduced from Asia in the seventeenth century. When found, it was named the "forbidden fruit"; and it has also been misidentified with the pomelo.
The evergreen grapefruit trees usually grow to around 5–6 meters (16–20 ft) tall, although they can reach 13–15 m (43–49 ft). The leaves are glossy dark green, long (up to 15 centimeters (5.9 in)) and thin. It produces 5 cm (2 in) white four-petaled flowers. The fruit is yellow-orange skinned and generally an oblate spheroid in shape; it ranges in diameter from 10–15 cm (3.9–5.9 in). The flesh is segmented and acidic, varying in color depending on the cultivars, which include white, pink and red pulps of varying sweetness (generally, the redder varieties are sweeter). The 1929 US Ruby Red (of the Redblush variety) has the first grapefruit patent.