yellow lady's slipper

NOUN
21 LETTERS · STARTS WITH Y

yellow lady's slipper is a valid 21-letter word worth 32 points in Scrabble and 36 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
Y4E1L1L1O1W4L1A1D2Y4'0S1S1L1I1P3P3E1R1
4 + 1 + 1 + 1 + 1 + 4 + 0 + 1 + 1 + 2 + 4 + 0 + 1 + 0 + 1 + 1 + 1 + 3 + 3 + 1 + 1 =32 PTS
DOUBLE WORD → 64TRIPLE WORD → 96
MEANING

What does yellow lady's slipper mean?