Strittmatter L. I., Hickey R. J., Negrón-Ortiz V., Heterochrony and its role in sex determination of cryptically dioecious Consolea (Cactaceae) staminate flowers, Botanical Journal of the Linnean Society, 2008, 156(2):305-326, doi: 10.1111/j.1095-8339.2007.00754.x
The study compares ovule development in six Consolea species. It discusses heterochrony and the occasional production of seeds by functionally male individuals.