A black rose isn't a real flower, we would like to artificially have one of these made for our opening sequence.
The reason for this is because when Dhylan (a main character) goes to the cemetery, we would like him to put these flowers on Tyler's grave (other main character). We want a black rose because black symbolises death and a rose is usually a loving flower. So we are trying to express both these things just by using a flower.
If we are unable to get a black rose, then we shall have to use other flowers that are black. But we prefer if it were a black rose.