Prince Harry and Meghan Markle
Prince Harry and Meghan Markle's wedding cake may include toxic decorative fresh flowers. Pictured: Prince Harry and Markle during an official photocall to announce their engagement at The Sunken Gardens at Kensington Palace on Nov. 27, 2017 in London. Getty Images/Chris Jackson

Some parts of Meghan Markle and Prince Harry's wedding cake may not be edible.

The "Suits" actress and Prince Harry announced earlier that they will not have the traditional fruit cake on their wedding day, the couple choosing a lemon elderflower cake instead. The sweet treat will incorporate the bright flavors of spring and will be covered with buttercream and decorated with fresh flowers.

According to Elizabeth Dauncy, a botanical toxicologist who worked for the poison unit in Guy's and St. Thomas' Hospital in London, some of the decorative fresh flowers may be poisonous, so guests should take caution.

"I don't think anyone's idea of a perfect wedding is calling for an ambulance for a guest who assumed the flowers decorating the cake were edible," Dauncey said (via Express).

Dauncey stressed that there is a range of flowers commonly used as a decorative garnish for sweet and savory dishes that are harmful when eaten. This includes delphiniums, ranunculus, clematis and anemones.

She explained that a picture of a cake produced by Claire Ptak's bakery, Prince Harry and Markle's wedding cake designer, included a fresh white anemone. According to the expert, the flower can irritate the skin and cause vomiting.

Ptak is popular for using organic ingredients in her pastries. She also uses a "simple, rustic style." "Claire Ptak, who was raised in California, focuses on using seasonal and organic ingredients in her cakes. Ms. Markle previously interviewed Chef Ptak for her former lifestyle website The Tig," the palace announced.

Initially, there were rumors that Prince Harry and Markle are having a banana cake for their wedding day because the pair is a huge fan of the fruit. "This will be the first royal wedding cake made from banana," a source said.

Prince Harry and Markle are set to tie the knot on May 19 at St. George's Chapel at Windsor Castle. They will have a carriage procession after the ceremony. The bride-to-be is reportedly anxious about the weather as long-range forecasts suggest that there will be heavy rain on that day.

"Like all brides, Meghan is all over the arrangements and a bit stressed," a source told The Sun. "But the one thing she can't control is the weather. She is asking about it several times a day."