Roses and apples are a species. Look at Apple and you will know. There are more than 7,500 kinds of apples in the world, and you have to eat for 20 years even if you eat one in a day. The most important thing is that roses and apples are family members, all of which belong to Rosaceae.
When you confess with your girlfriend in the future, you can try to use apples. After all, apples are cheaper than roses and can be eaten at the same time.