Yes, SPIRAEAS is a Scrabble word!

Letter values in Scrabble US: S 1, P 3, I 1, R 1, A 1, E 1, A 1, S 1.

Is it a valid word?

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

a Japanese shrub that resembles members of the genus Spiraea; widely cultivated in many varieties for its dense panicles of flowers in many colors; often forced by florists for Easter blooming
any rosaceous plant of the genus Spiraea; has sprays of small white or pink flowers
a dicotyledonous genus of the family Rosaceae

Also: astilbe japonica, genus spiraea.