The rose is made out of rice paste, a floral paste made out of rice flour. It’s my favourite paste as it’s very simple to make, the texture is great, very easy to work with and can be made into more realistic flowers with less effort. Rice paste flowers are very delicate, looks pure and transparent. It’s also stronger than gum paste.
I have a tutorial teaching everything about the medium here:
https://cakejess.com/course/amazing-rice-paste-flowers/