original_query: What is the significance of the wall of framed wildflowers in Vanger's mansion on Hedeby Island?
query: What is the significance of the wall of framed wildflowers in Henrik Vanger's mansion on Hedeby Island?
answer: The wall of framed wildflowers represents the annual birthday gift Henrik Vanger received from his niece Harriet for 36 years, until her disappearance at age 16.  Each flower marked another year, and the wall serves as a constant reminder of her disappearance and the unsolved mystery surrounding it.