yellow lady-slipper

NOUN
19 LETTERS · STARTS WITH Y

yellow lady-slipper is a valid 19-letter word worth 31 points in Scrabble and 35 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
Y4E1L1L1O1W4L1A1D2Y4-0S1L1I1P3P3E1R1
4 + 1 + 1 + 1 + 1 + 4 + 0 + 1 + 1 + 2 + 4 + 0 + 1 + 1 + 1 + 3 + 3 + 1 + 1 =31 PTS
DOUBLE WORD → 62TRIPLE WORD → 93
MEANING

What does yellow lady-slipper mean?