How Princess Diana was honored at Prince Harry and Meghan Markle's royal wedding

Princess Diana's spirit was certainly felt as her youngest son, Prince Harry, said "I do" to Meghan Markle on Saturday at St. George's Chapel in Windsor, England.

The couple was sure to include some subtle tributes to the late Princess of Wales, who died nearly 21 years ago, in both the ceremony and even in the floral arrangements.

Diana’s sister, Lady Jane Fellowes, gave the only reading in the ceremony from the Song of Solomon, while her other two siblings, Earl Spencer and Lady Sarah McCorquodale, were also in attendance.

In a statement earlier this month released from Kensington Palace, the couple said they were "keen to involve [Harry's] mother's family in his wedding," and felt "honored" that Lady Jane would be "helping to celebrate the memory of the late princess on the wedding day."

The service also included the hymn "Guide Me, O Thy Great Redeemer," which was sung at Diana's funeral in 1997.

In addition to the reading and the hymn, Harry, 33, and Meghan, 36, also honored the People's Princess by having lots of white flowers strewn about the chapel. Diana is said to have loved white flowers, roses in particular.

As for Meghan's bouquet, Harry reportedly handpicked several flowers from Kensington Palace to include in the arrangement, including forget-me-nots, another beloved flower of Diana’s.

There is expected to be another tribute when Diana's dear friend, Elton John, performs at the couple's wedding reception. A source told ET on Friday that the singer will take a moment to honor Diana and "say how much she is missed on this very special day."