Vascular plants are well studied in Iowa. There is a book that contains a list for Iowa. It is:

Eilers, Lawrence J. and Dean M. Roosa. 1994. The Vascular Plants of Iowa, An Annotated Checklist and Natural History. University of Iowa Press, Iowa City, Iowa.

That book lists 1958 species known to occur in Iowa. It also lists ranges and gives an indication as to whether the species is native to Iowa or introduced.

In addition, Iowa State University has an herbarium, which is sort of a library for preserved (mostly dried and pressed) plants.

There are active groups and organizations in Iowa that are involved with the conservation of native plants, and also with the re-introduction of natural plants where they have been removed. These groups include the Iowa Native Plant Society, The Iowa Prairie Network, and several private and governmental conservation organizations. People who have not been involved with these groups might not realize how many people are involved and how active these groups are.

Prairie seed collecting activities and "prairie rescues" (where invading woody plants such as red cedar are removed from original or reconstructed prairies) are fun social activities that give people an excuse to get out in nature. The Iowa Native Plant Society sponsors field trips that are generally open to the public. If you have not attended such an event you owe it to yourself--you will love it.

Many landowners are finding great pleasure in attempting to salvage remnants of prairie, or re-constructing prairie.  My father got interested in prairie, and created a prairie reconstruction in a small portion of his back yard.  It gave him great pleasure in the final decades of his life.  That's him on the upper right photograph.  He spent many happy hours collecting seeds for the Neal Smith National Wildlife Refuge, and I went with him and spent many happy hours photographing flowers and the insects that rested on them.