Yes, CATAPHYLL is a Scrabble word!

Letter values in Scrabble US: C 3, A 1, T 1, A 1, P 3, H 4, Y 4, L 1, L 1.

Is it a valid word?

CATAPHYLL is a valid word in the official Scrabble dictionary (US) and the UK Scrabble Dictionary, but not in Words with Friends (ENABLE).

a reduced or scarcely developed leaf at the start of a plant's life (i.e., cotyledons) or in the early stages of leaf development