I describe Lily as an eighteen year old girl, with bright red hair and green eyes. The easy explanation is that I'm describing my daughter, Brecken.
Red hair is unusual. It is the least common hair color, because it's the result of a genetic improbability. Both parents must have red hair as a recessive gene, and the child must get both of those recessive genes. So, even if both parents are carriers of that red gene, the child still only has a 1 in 4 chance of being born with red hair. (That's as close to science as I get, I promise!)
Now, those gingers have gotten a bad rap in the past, very negative connotations that were the product of superstitious times. Aristotle thought that people with red hair had bad character. The Ethopians described Theracians as having red hair and blue eyes, and thought they were possessed!
Herodotus described the Budini as a tribe in Scythia, that had red hair. Which ties in a bit with Planted, because Herodotus is part of the background of this story. He is a very important person, and has had an effect on Lily's life, even though she has no idea.
Green eyes are unique also, the least common eye color. And, the combination of red and green is just beautiful, in my opinion, and reinforces the idea that this girl is special.
I've spoken previously about my ideology: I'm writing about Lily because she is interesting, and unique. Hopefully this will play out in the book.