Abstract:

Plants that have a dimorphic mixed-mating system consisting of open chasmogamous flowers (CH) and closed cleistogamous flowers (CL) have special reproductive strategies. Further research on CH-CL mating systems can help us understand the maintenance mechanism, evolutionary trends and strategies of plants in response to environmental change. This paper reviews existing literatures on dimorphic flowers (dimorphic mixed-mating system) of CH-CL systems including the effects of different abiotic and biological factors on the growth, development and relative proportion of flowers. It also reviews the maintenance mechanisms and evolutionary significance of dimorphic flowers. Recent researches of CH-CL system and remaining scientific questions are outlined and the new understanding of CH-CL systems based on recent research is reviewed. We suggests that it is necessary to accurately detect the differences between the progeny of the two flower forms in heterogeneous habitats and at different stages of life history. The microenvironment (separation pattern and location effect of seeds) is also identified as being very important for seed germination and the growth and development of the two flower types. Additionally, the expression mechanism of the spatial and temporal differences in flower types (the pattern of flowering and sensitivity to heterogeneous habitats) may be related to changes at the levels of endogenous hormones. It has been said that the distribution of populations of different natures and different sources, and the impact on the genetic structure, is likely to be an important mechanism for the maintenance of the system. Therefore, in-depth research and scientific understanding of dimorphic mixed-mating system may be of great significance for understanding the evolution of the entire plant reproductive system.

Key words: CH-CL system, fitness, Chasmogamous flower, Cleistogamous flower, Maintenance mechanism