Botanical Society of America - http://www.botany.org/ - promotes research and teaching in all fields of plant biology.
Botanizing 101 - by Rebecca Dolan. First published in the INPAWS Journal, these articles explore plant nomenclature and the basics of identifying native plants in the field.
Center for Plant Conservation - is the only national organization in the U.S. dedicated solely to preventing the extinction of U.S. native plants. Founded in 1984, the CPC operates a national program of ex situ conservation, research, education and restoration through a consortium of 28 leading botanical gardens and arboreta.
Center for Urban Ecology and Sustainability at Butler University (CUES) - builds upon a solid history of student-faculty research and community service to foster and support the exploration and stewardship of the urban ecosystems of Indianapolis.
Conserving Indiana - The Central Indiana Land Trust (CILTI) - the Central Indiana Land Trust Incorporated preserves natural areas, improving air and water quality and enhancing life in our communities for present and future generations.
Consortium of Pacific Northwest Herbaria - represents herbaria in Alaska, Idaho, Montana, Oregon, Washington, and the Canadian provinces of British Columbia and Yukon Territory.
Environmental Education Association of Indiana - dedicated to promoting environmental education for all Indiana citizens.
Florida Museum of Natural History, University of Florida Herbarium (FLAS) - holdings of approx. 1/2 million specimens.
Floridata - online photo reference of plants.
Google Scholar - gives bibliographic access to the scholarly literature.