One of the first things I learned when I started getting paid for my photographs so many years ago is that almost any photograph needs a sense of scale. The obvious standard for scale is the human being. 

A person standing by a tall building will give you an idea of size.

With my scans of roses and plants which I always scan at an accurate 100% size a lonely rose with no comparison (certainly not a human unless you use a hand) will be of an uncertain dimension.

The three roses in this scan I have shown in these blogs here, here and here. Now you can observe that one of them, Rosa ‘Princess Alexandra of Kent’ is large. In fact it measures five inches across. 

There was another factor that I learned particularly in my early years as an industrial photographer for Air Canada and Canadian Pacific Limited. The PR man for Air Canada, Harry Atterton, (last seen around 2006 when he and his wife Jacqueline restored a famous chatteau in France) told me that a human presence was important in all my photographs. He said, "I don't care if you have to insert in a shoe in your photo. Do it."