Asymmetrical disassortative pollination mediated by long‐/short‐tongued pollinators in a distylous Limonium myrianthum (Plumbaginaceae) with a short corolla tubular small flower

In heterostylous plants, short‐tongued pollinators are often ineffective/inefficient owing to the limitations imposed by a long corolla tube. However, it is unclear how disassortative pollen transfer is achieved in small flowers. We investigated the pollination pattern and floral morph variation by analyzing heterostylous syndrome, pollinator groups, and pollen deposition after a single visitation in two Limonium myrianthum populations with short‐corolla‐tubular small flowers. The predominant pollinators in the Hutubi population were pollen‐seeking short‐tongued syrphids, which can only transfer pollen between high‐level sexual organs. In the Xishan population, nectar‐seeking short‐tongued insects were efficient pollinators with symmetrical disassortative pollen transfer between high‐ and low‐level sexual organs, whereas long‐tongued pollinators had a low efficiency between high‐level sexual organs due to the low contact probability with the stigma of long‐styled flowers (L‐morph), which no longer offered the same advantage observed in tubular flowers. Asymmetrical disassortative pollination may cause the female fitness of short‐styled (S‐morph) individuals in the Hutubi and L‐morph individuals in the Xishan population to suffer greater selection pressure and exhibit a higher degree of floral morph variation. Limonium myrianthum exhibits an unusual pollination pattern in which the small flowers with short corolla tubes make it possible for short‐tongued insects to become effective pollinators. However, factors such as the position of stigma–anther within the flower, pollinator species and their preference further caused asymmetrical disassortative pollen transfer. Therefore, more factors should be considered when evaluating the effectiveness of short‐ and long‐tongued insects in pollination service. The pollination efficiency and their effects on floral morph variation of short‐tongued and long‐tongued pollinators were investigated in two Limonium myrianthum populations with short corolla tubular small flowers and considerable floral morph variation. We found that asymmetrical disassortative pollination affects floral morph variation. Compared with nectar‐seeking ST insects, pollen‐seeking ST insects and LT insects caused asymmetrical disassortative pollen transfer between high‐ and low‐level sexual organs due to the preference for reward and the position of stigmas/anthers within the flower.