Yes, POINCIANA is a Scrabble word!

Letter values in Scrabble US: P 3, O 1, I 1, N 1, C 3, I 1, A 1, N 1, A 1.

Is it a valid word?

POINCIANA is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

small subgenus of ornamental tropical shrubs or trees; not recognized in some classifications
a tropical flowering shrub having bright orange or red flowers; sometimes placed in genus Poinciana

Also: subgenus poinciana, bird of paradise, caesalpinia gilliesii, poinciana gilliesii.