According to their website, The Native Plant Society of Northeastern Ohio was founded in 1984 under the wing of the Ohio Native Plant Society. Their goal is to promote the study, appreciation, and conservation of Ohio's native plants and plant communities.
The Mohican Native Plant Society is based in North Central Ohio. They schedule lots of outdoor activities involving native plants. Check out their newsletter through their website.
The Cincinnati Wildflower Preservation Society is the Southwestern Ohio Chapter of the Ohio Native Plant Society and is celebrating the 99th year of their organization. They sponsor field trips, “Give Back Days” and hold lectures on a variety of topics throughout the year.
The Midwest Native Plant Society hosts the Annual Midwest Native Plant Conference. Please see their website for more information.
The Wilderness Center located in Wilmot, Ohio sponsors a group of wildflower minded individuals interested in observing plants in the field. Join the TWC Botanizers Club!
The New York Botanical Garden’s The LuEsther T. Mertz Library, the most comprehensive botanical and horticultural library in the Americas, has cataloged all 58,000 items in its Nursery and Seed Trade Catalog Collection and digitized the complete contents of 1,400 catalogs printed before 1923 and in the public domain. Above you can see the cover of the Springfield, Ohio Nursery Good & Reese Co. from 1908. The nursery and seed catalogs in the Mertz Library may be searched by author, title, subject and keywords using the online catalog.
Trees of Ohio Field Guide by 
The Search for Lost Habitats by 
Women botanists of Ohio born before 1900 : with reference calendars from 1776 to 2028 by 
Wildflowers of Tennessee and the East Central States by 
Frontier Botanist William Starling Sullivant's Flowering-Plant Botany of Ohio (1830-1850) by 
William Starling Sullivant (1803-1873), considered to be one of the greatest bryologists of the 19th century, lived his entire life in Ohio. He was a self-taught botanist who became an expert in mosses and liverworts. According to Asa Gray, Sullivant laid the foundation for the general study of bryology with his contribution of his account of the Musci and Hepaticae of the Ohio region to Gray’s Manual of the Botany of the Northern United States.