Heiser was very active after retirement, continuing to write and further his research. “Most days he could be found in the greenhouse attending to various bizarre-looking plants. His work on hybridization in the sunflower genus inspired and informed subsequent work by Loren Rieseberg, who was recently honored for his work on sunflowers,” said Roger Innes, chair of the IU Department of Biology. “Charley was also known for his disarming sense of humor and quick smile, and was much loved by his students, including 29 doctoral students, many of whom went on to stellar careers. We will miss him very much.”

One of Heiser’s doctoral students, Jeffrey Doyle, MA’77, PhD’81, now a professor of plant biology at Cornell University, remembers his mentor’s passion. “It was never work for him—it was more like a full-time hobby,” noted Doyle, who visited campus in October 2007 to give a seminar in honor of Heiser’s 60 years of service to Indiana University. During the visit, Doyle recalls: “He took me out to the experimental field and showed me all the plants he was still working with; it reminded me of my first trip out there over 30 years earlier when he showed his new students his rows of peppers, the hybrid honey locust trees, and his sunflowers. Same Charley! That’s how I’ll remember him, and I hope I convey to my own students even a fraction of his passion and joy. It is hard to imagine the world without him. But then, I think, whenever I see a sunflower or a honey locust, or eat a hot pepper, or recall any of the many cultivated plants of Andean origin . . . well, a part of Charley is there!”

Gregory Anderson, PhD’71, retired vice provost of research from the University of Connecticut, remembers Heiser’s high scientific standards, his love of writing, and his pervasive dry sense of humor, which he often turned upon himself. “He did not mince words when talking about your, his, or anyone’s quality of science, their logic or their work. This was sometimes hard to take, but always valuable, and eventually . . . valued,” Anderson said. Most of all, Anderson appreciated Heiser’s strong commitment and loyalty to “botany, to science, to his family, to his students, and to Indiana and especially to IU.”

Another of Heiser’s former students, W. Hardy Eshbaugh, MA’61, PhD’64, says that his mentor’s influence on his professional career cannot be overstated. Eshbaugh came to IU planning to earn an MAT to become a high school teacher. Heiser convinced him instead to consider a career as a college professor and to continue his research on peppers. “This was very far beyond my horizon!” Eshbaugh recalled in a note to Heiser’s children. “Now these many years later I have spent the vast majority of my career as a professor at Miami University. Your father started me on one incredible journey,” he told them, “and I will be forever grateful for that. I was the first in my family to get a college degree and I really had no idea what a PhD entailed or what it would mean. I had struggled as an undergraduate at Cornell. However, graduate school was a different matter, and your father started me on a long love affair with learning that continues to this day.”

Heiser was president of several key organizations—including American Society of Plant Taxonomists, Society for the Study of Evolution, Society for Economic Botany, and the Botanical Society of America. His honors include the Guggenheim Fellowship, Gleason Award of the New York Botanical Garden, Merit Award and Centennial Award of the Botanical Society of America, Distinguished Economic Botanist from the Society of Economic Botany, Pustovoit Award from the International Sunflower Association, the Asa Gray Award from the American Society of Plant Taxonomists, Distinguished Scholar Award from the Indiana Academy of Science, and the Raven Award presented by the American Society of Plant Taxonomists. Heiser was elected to the National Academy of Sciences in 1987.