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A. Biggest colpi length, B. Exine width at the equatorial zone; Salvia assurgens, S. uliginosa (South American) and other Mexican Salvia species (A: 24 spp; B: 22 spp). Average values are shown for each. Range is indicated by horizontal bars (min-max). The two values in S. coccinea are from different studies.
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The present study provides novel information about the pollen of Salvia assurgens. Pollen grains were collected and described based on their observed characters by light microscope and scanning electron microscopy. The species is distinguished from other Mexican salvias by having small pollen grains (14.2 × 18.2 µm), thin primary muri (0.2 µm thick...
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Context 1
... places it near the extreme of grains that are very elongate in the equatorial axis (Fig. 2 B: suboblate). Only S. occidentalis Swartz (1788: 14) and S. coccinea have pollen grains that are more elongate than S. assurgens (Fig. 2 B). On the other hand, exine thickness is similar to that of species with twice or three times larger pollen grains (Fig. 2 A, 3 A): S. ballotiflora, S. farinacea, S. hispanica Linnaeus (1753: 25), S. microphylla Kunth in Humboldt et al. (1818: 295), S. reflexa Hornemann (1807: 34) and S. uliginosa. When the relationship between style length and pollen size is examined (P and E), a positive correlation was observed, with bigger pollen size associated with longer ...
Context 2
... of the 24 species included could be distinguished by using the evaluated traits (see Table 1 and 2), which coincides with previous findings (Orsini et al. 2006, Kahraman et al. 2009, Saravia & Pinto 2018). In particular, colpi length can be a very useful taxonomic feature to differentiate species, as reported by Orsini et al. (2006) (Table S1, Fig. 3 A). Regarding the recognition of sections or clades (Fragoso et al. 2018), there is not sufficient evidence of a unique palynological feature or a combination of features that consistently allows identifying or grouping the American Salvia species. For example, polygonal primary lumina are present in species of sect. Angulatae (Epling ...
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... [26]. Recently, studies on the micromorphology of Lamiaceae focused mainly on the structure and distribution of leaf trichomes [27][28][29][30][31][32][33][34] and on the taxonomic implications of pollen morphology [27,32,[35][36][37][38][39]. ...
Floral micromorphology and pollen morphology of two Leonurus (Lamiaceae) species were examined and compared using scanning electron microscopy to evaluate the diagnostic value of these features to facilitate future studies on floral biology and taxonomy. Floral epidermal patterns were similar in both species, with the conical to central-conical epidermal cells on the adaxial side of the lower lip (corolla). Capitate, peltate, scale-like glandular, and non-glandular trichomes were distributed on the surface of the floral organs. Notably, scale-like anther glands and floral stomata were found on the anthers and abaxial side of the calyx, respectively. Pollen grains had bi-reticulate exine with angular primary lumina and rounded secondary lumina. These characteristics provide indirect evidence of a close association between plant-pollinator interactions and effective pollination. In addition, quantitative traits of pollen grains and trichome types on the adaxial side of the lip differed between the two species. These characteristics may have diagnostic and taxonomic value for the genus Leonurus and family Lamiaceae.
... The presence of pollen grains of S. assurgens in the pollen loads was verified by comparison to the pollen obtained from mature flower buds from the same S. assurgens populations. The micromorphological characteristics considered to identify the pollen grains of S. assurgens are the follow-ing: 1) polar region length (P), 2) equatorial region length (E), 3) length of the largest colpus, and 4) thickness of the exine (Moon et al., 2008; see more details in Bedolla-García et al., 2020b). Additionally, videos of flower visitation by insects were recorded to document in slow motion 1) how visitors approach flowers and 2) their behavior after visiting flowers (e.g., grooming behavior). ...
Background and Aims: Salvia assurgens (a white-flowered sage) is considered to be a melittophilous species due to its floral architecture. However, there are no current empirical data supporting its assignment to this pollination syndrome. The present study aimed to record the diurnal floral visi-tors of S. assurgens to confirm its characterization as melittophilous and to evaluate which species of bees are potential pollinators.
Methods: We collected wild bee visitors to the flowers of one population of S. assurgens in northeastern Michoacán, Mexico, during the summers of 2018 and 2019. We analyzed the pollen loads of each bee species and body area. In addition, we recorded the behavior of some wild bees when visiting flowers of S. assurgens.
Key results: Seventeen bee species from three families (Apidae, Halictidae, and Megachilidae) were recorded as floral visitors of S. assurgens. Ninety percent of pollen carried by the examined bees belonged to S. assurgens. Four species of wild bees were the most frequent visitors, with S. assurgensaccounting for 94.2% of the pollen on their bodies. Notably, these species presented clear differences in the distribution of pollen on their body parts: two of them, Bombus pennsylvanicus sonorus and Megachile sp. 1 accumulated up to 90% of the pollen on the frons and dorsal area of their thorax. It is most likely that pollen is transferred from these body areas to the stigma of S. assurgens.
Conclusions: The present study provides evidence of the melittophilous pollination syndrome of S. assurgens. The wild bee richness recorded in this study is as high as that previously reported in studies on floral visitors to Neotropical sages. Finally, our results highlight the usefulness of considering pollen loads to increase our knowledge of Salvia pollination ecology
