Are scientific illustrations natural process art? That is up for debate, but in my opinion any art that is based on direct observations of nature can be considered natural process art, so long as the intent is not only to illustrate an idea, or present a thing, but present it in an aesthetic, visually appealing way. The intent is also to create something beautiful, not just educational, or scientifically accurate.

The work of Ernst Haeckel definitely fits into this category. Not only does it offer an accurate reporting of biological forms in their various environments and life cycles, but does so in a staggeringly beautiful, graphically intriguing manner.

All work from "Kunst Formen der Natur".

https://ucmp.berkeley.edu/history/haeckel.html