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Reproductive traits that function in pollinator attraction may be reduced or lost during evolutionary transitions from outcrossing to selfing. Although floral scent plays an important role in attracting pollinators in outcrossing species, few studies have investigated associations between floral scent variation and intraspecific mating system transitions. The breakdown of distyly to homostyly represents a classic example of a shift from outcrossing to selfing and provides an opportunity to test whether floral fragrances have become reduced and/or changed in composition with increased selfing. Here, we evaluate this hypothesis by quantifying floral volatiles using gas chromatography‐mass spectrometry in two distylous and four homostylous populations of Primula oreodoxa Franchet, a perennial herb from SW China. Our analysis revealed significant variation of volatile organic compounds (VOCs) among populations of P. oreodoxa. Although there was no difference in VOCs between floral morphs in distylous populations as predicted, we detected a substantial reduction in VOC emissions and the average number of scent compounds in homostylous compared with distylous populations. A total of 12 compounds, mainly monoterpenoids and sesquiterpenoids, distinguished homostylous and distylous morphs; of these, (E)‐β‐ocimene was the most important in contributing to the difference in volatiles, with significantly lower emissions in homostyles. Our findings support the hypothesis that the transition from outcrossing to selfing is accompanied by the loss of floral volatiles. The modification to floral fragrances in P. oreodoxa associated with mating system change might occur because high selfing rates in homostylous populations result in relaxed selection for floral attractiveness. [ABSTRACT FROM AUTHOR]

Pollination precision and efficiency have been deemed to be important driving forces in floral evolution. Herkogamy reduction is a main mechanism to increase pollination precision. Secondary pollen presentation (SPP), by which pollen is presented on other floral organs especially pistils, has been widely accepted as a special mechanism to increase pollen transfer precision through spatial reduction of the anther–stigma distance, that is, minimized herkogamy. This overlooks a potential driving force, that is expanding the pollination niche through converting pollen thieves and nectar robbers into effective pollinators. We selected two species as study models with typical pistillate SPP, Pavetta hongkongensis Bremek. (Rubiaceae) and Scaevola taccada (Gaertn.) Roxb. (Goodeniaceae). In both species, two distinct pollinator functional groups were recognized. Short‐tongued bees and flies fed on pollen on stigmas but also stole pollen from anthers and robbed nectar, whereas long‐tongued hawkmoths and butterflies only collected nectar. Emasculation had no influence on long‐tongued pollinators, but significantly decreased the visitation frequency of short‐tongued visitors and fruit set, compared to intact flowers, demonstrating short‐tongued visitors did not effectively pollinate and acted merely as pollen thieves or nectar robbers when SPP was absent. Data from the two plant species clearly indicated pistillate SPP has additional adaptive advantages of converting ineffective visitors into pollinators and consequently widening the pollination niche, which could help plants overcome environmental stochasticity. Our results suggest that multiple selective forces drive the evolution of SPP and the minimization of herkogamy. [ABSTRACT FROM AUTHOR]

A new species of Primula, P. chimingiana G. Hao, S. Yuan & D.X. Zhang, is illustrated and described from Sichuan province, China. The new species is assigned to P. sect. Petiolares based on general morphology. It is similar to P. odontocalyx in the lack of farina and of hairs, the absence of basal scales at anthesis, and the occasional toothing of the calyx lobes, but can be easily distinguished by its calyx being as long as or slightly longer than the corolla tube, and cut to two‐thirds of its length into lanceolate lobes, and by its leaves with recurved teeth on the margin. [ABSTRACT FROM AUTHOR]

Based on morphological and palynological comparisons, three names, viz., Glochidion mishmiense Hook. f., G. pseudo-obscurum Pamp., and G. rubidulum Chin are reinstated. The three names have previously been reduced to synonymy of G. zeylanicum var. tomentosum (Dalzell) Trimen, G. puberum (L.) Hutch., and G. thomsonii (Muell. Arg.) Hook. f., respectively. Floral morphological characters of G. mishmiense are described here for the first time. In addition, G. mishmiense and G. pseudo-obscurum are lectotypified, and G. mishmiense is newly recorded in China, while the record of G. thomsonii in China is rejected. [ABSTRACT FROM AUTHOR]