References
Knox, J.S. 1987. An experimental garden test of characters used to distinguish Helenium virginicum Blake from H. autumnale L. Castanea 52: 52-58. Google Scholar
Knox, J.S. 1987. An experimental garden test of characters used to distinguish Helenium virginicum Blake from H. autumnale L. Castanea 52: 52-58. Google Scholar