To describe ecological interactions of a plant with all the different components. A software that can add photos. For a blog post or even an article to be submitted for publication!
I would recommend "Edraw Max Software v.9" which has 30 days trial period. It is a vector-based diagramming software with many examples and templates for easy generation of Circular Diagrams.
https://www.edrawsoft.com/Circular-Diagram.php
In my opinion, Draw.io is probably one of the best free alternatives.
https://download.draw.io
If you are looking another free software, you have a lot of options. You can try some of them and see what is the most suitable for you.