Yes, PONDEROSAS is a Scrabble word!

Letter values in Scrabble US: P 3, O 1, N 1, D 2, E 1, R 1, O 1, S 1, A 1, S 1.

Is it a valid word?

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

common and widely distributed tall timber pine of western North America having dark green needles in bunches of 2 to 5 and thick bark with dark brown plates when mature

Also: ponderosa pine, western yellow pine, bull pine, pinus ponderosa.