calamagrostis

NOUN
13 LETTERS · STARTS WITH C

calamagrostis is a valid 13-letter word worth 18 points in Scrabble and 22 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
C3A1L1A1M3A1G2R1O1S1T1I1S1
3 + 1 + 1 + 1 + 3 + 1 + 2 + 1 + 1 + 1 + 1 + 1 + 1 =18 PTS
DOUBLE WORD → 36TRIPLE WORD → 54
MEANING

What does calamagrostis mean?