dog's-tooth violet

NOUN
18 LETTERS · STARTS WITH D

dog's-tooth violet is a valid 18-letter word worth 23 points in Scrabble and 25 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
D2O1G2'0S1-0T1O1O1T1H4V4I1O1L1E1T1
2 + 1 + 2 + 0 + 1 + 0 + 1 + 1 + 1 + 1 + 4 + 0 + 4 + 1 + 1 + 1 + 1 + 1 =23 PTS
DOUBLE WORD → 46TRIPLE WORD → 69
MEANING

What does dog's-tooth violet mean?