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.
I imagine you already found your program, but I thought I'd put my tuppence worth.
I normally use Adobe Illustrator to create flowcharts because it is quite versatile. You can create your own or you can download lots of free templates from many websites and then customise them as you like. It is not the easiest way to do it --the learning curve is a bit steep if you've completely new to editing vectors-- but the final results are worth the trouble. You can also create your flowcharts in another program, save them as vector images, and give them the final touches in Illustrator.