Fig 5 - uploaded by Zhi-Qiang Zhang
Content may be subject to copyright.
Comparisons of female fitness (mean ± SE) among plants with bracts removed before flowering (white bars), plants with bracts removed after flowering (light gray bars), and control plants (dark gray bars), at Huluhai (a) and Yongjiongyi (b). Different letters denote significant differences at P \ 0.05. FS Fruit set, AR seed abortion rate, PR seed predation rate, MA seed mass, GR seed germination rate
Source publication
Specialized bracts are thought to be important for the successful reproduction of some plants and are regarded as adaptations to diverse driving forces. However, few empirical studies have quantified the adaptive significance of bracts within a cost-benefit framework. We explored the adaptive significance of large and showy bracts for reproduction...
Contexts in source publication
Context 1
... the Huluhai population, fruit set of the control plants was significantly higher than that for plants with their bracts removed before flowering, but not higher than those that had their bracts removed after flowering (F 2, 19 = 219.70, P \ 0.001; Fig. 5a). In the Yongjiongyi popula- tion, fruit set in the control plants was significantly higher than in plants with their bracts removed before or after flowering (F 2, 21 = 146.63, P \ 0.001; Fig. 5b). In both populations, seed abortion in control plants was signifi- cantly lower than in plants with their bracts removed before or after ...
Context 2
... with their bracts removed before flowering, but not higher than those that had their bracts removed after flowering (F 2, 19 = 219.70, P \ 0.001; Fig. 5a). In the Yongjiongyi popula- tion, fruit set in the control plants was significantly higher than in plants with their bracts removed before or after flowering (F 2, 21 = 146.63, P \ 0.001; Fig. 5b). In both populations, seed abortion in control plants was signifi- cantly lower than in plants with their bracts removed before or after flowering (Huluhai, F 2, 19 = 42.25.70, P \ 0.001; Yongjiongyi, F 2, 21 = 53.89, P \ 0.001; Fig. 5a, ...
Context 3
... higher than in plants with their bracts removed before or after flowering (F 2, 21 = 146.63, P \ 0.001; Fig. 5b). In both populations, seed abortion in control plants was signifi- cantly lower than in plants with their bracts removed before or after flowering (Huluhai, F 2, 19 = 42.25.70, P \ 0.001; Yongjiongyi, F 2, 21 = 53.89, P \ 0.001; Fig. 5a, ...
Context 4
... seed predation in the control plants was significantly higher than in plants with their bracts removed before or after flowering in both the Huluhai (F 2, 19 = 101.05, P \ 0.001; Fig. 5a) and the Yongjiongyi (F 2, 21 = 24.30, P \ 0.001; Fig. 5b) ...
Context 5
... seed predation in the control plants was significantly higher than in plants with their bracts removed before or after flowering in both the Huluhai (F 2, 19 = 101.05, P \ 0.001; Fig. 5a) and the Yongjiongyi (F 2, 21 = 24.30, P \ 0.001; Fig. 5b) ...
Context 6
... mass was higher in the control plants than in those with their bracts removed before or after flowering (Huluhai, F 2, 72 = 109.17, P \ 0.001; Yongjiongyi, F 2, 72 = 408.67, P \ 0.001; Fig. 5a, b). nobile plant with bracts (dark gray bars) and without bracts (white bars) during the day and at night, respectively (n = 16). Different letters denote significant differences at P \ ...
Context 7
... germination for the control plants was significantly higher than for plants with their bracts removed before or after flowering in both populations (Huluhai, F 2,15 = 24.27, P \ 0.001; Yongjiongyi, F 2,15 = 38.29, P \ 0.001; Fig. 5a, ...
Context 8
... (e.g., low temperature, high levels of UV, and heavy rain) have been found to affect seed development negatively ( Nayyar et al. 2007;Kaur et al. 2008). Bract removal after flowering in R. nobile did, indeed, have a negative effect on seed development, adversely affecting fruit set, abortion rate, seed mass, and subsequent seed germination (Fig. 5a, b). The positive effect of bracts during seed development may stem from a number of characteristics. First, seed development needs specific cumulative temperatures, to which cell division is sensitive (Egli and Wardlaw 1980;Boyer 1982;Kumar and Omae 2008). The bracts of R. nobile are able to increase the temperature of ripening fruits by ...
Citations
... Many species Hollow culms, as in Avena sativa from Magadan, Russia attain temperature excesses within of about 4 C in sunshine and for Phragmites australis temperature excesses with culms of 6.3 • C. The thermal regimes in the boot (reproductive structures enclosed in the developing flag leaves (bracts) and husks as in maize (Zea mays) seem not to have been investigated but we recorded temperature excesses of about 1-2 • C in ears on a production field margin in 2023. Song et al. (2013, ). ...
... Table 1 lists various taxa of plants in which the flowers produce especially well-developed calyces that continue to enclose the corolla after anthesis as proximally connate sepal(s) or as a symsepalous calyx, sometimes referred to as a syncalyx. The syncalyx of many species of Silene presumably function as microgreenhouses, as shown for two Arctic species (Kevan 2020 (Omori and Ohba 1996;Omori et al. 2000;Iwashina et al. 2004;Tsukaya 2002;Song et al. 2013) (Table 1, row 33) at high elevations in the Himalayas. The involucral bracts, well known in many Asteraceae, enclose air spaces that likely become warm and protect the inflorescence within. ...
Plant structures that enclose trapped air are morphologically and taxonomically diverse. They range from pubescence (trichomes) on various parts of plants to flowers, inflorescences, stems, culms (above-ground jointed stems of grasses), petioles, peduncles, scapes, fruits, bracts, leaves, galls, algal pneumatocysts, moss sporophytes, lichen podetia, and fungal fruiting bodies. Despite being familiar, such structures have not been studied systematically until recently when their complex thermodynamic functionality as microgreenhouses has been recognized. We propose the term “heliocaminiform” (Greco-Latin origin for “sun-room”) provides an umbrella term that describes form and function. Almost all the hollow structures we have examined have elevated internal temperatures of several degrees C above the surrounding air in sunshine, but those are abolished under cloud or at night. The potential importance for the additional heat is presumed to be in growth, maturation, reproduction, sexual function, and overall fitness of the plants. There seem to be no experimental studies on those effects even though they may help explain aspects of plants’ responses to climate change and to phenological mismatches with symbionts (mutualists and herbivores) as ecologically co-dependent partners. Our review and observations opens a remarkably new and hitherto surprisingly neglected avenue in botany which we hope others will explore.
... The elongated inflorescence is protected by large, nonphotosynthetic bracts which constitute a large portion of the biomass. The bracts increase the daytime temperatures of the flowers and fruits, buffer changes in humidity, greatly decrease ultraviolet B light and ultraviolet C light exposure, enhance pollen germination, pollinator visitation, and pollinator fecundity and subsequent fruit set (Song et al., 2013(Song et al., , 2015. Miller (1986) found that flowers of Andean slope Puya species with glabrous and nonlanate pubescence tracked ambient temperature. ...
Phylogenomics enhances our understanding of plant radiations in the biodiverse Andes. Our study focuses on Puya , primarily Andean and a part of the Bromeliaceae family. Using a phylogenomic framework based on the Angiosperms353 probe set for 80 species, we explored Puya ′s phenotypic evolution and biogeography. Divergence time analyses and ancestral area estimations suggested that Puya originated in Central Coastal Chile around 9 million years ago (Ma). Subsequently, it dispersed to the dry valleys of the Central Andes and Puna regions between 5–8 Ma, leading to the emergence of major lineages. Key events in the last 2–4 million years include the recolonization of Chilean lowlands and dispersal to the northern Andes via Peru's Jalcas, facilitating passage through the Huancabamba depression. This event gave rise to the high‐elevation Northern Andes clade. Using phylogenetic comparative methods, we tested the hypothesis that adaptation to the Andes' island‐like high‐elevation ecosystems was facilitated by unique leaf and floral traits, life history, and inflorescence morphology. Our findings suggest correlations between inflorescence axis compression, protective bract overlap, and high‐elevation living, potentially preventing reproductive structure freezing. Semelparity evolved exclusively at high elevations, although its precise adaptive value remains uncertain. Our framework offers insights into Andean evolution, highlighting that lineages adapted to life in dry ecosystems can easily transition to high‐elevation biomes. It also underscores how the island‐like nature of high‐elevation ecosystems influences phenotypic evolution rates. Moreover, it opens avenues to explore genetic mechanisms underlying adaptation to extreme mountain conditions.
... High doses of UV-radiation have been widely documented to induce plant stress, resulting in decreased biomass accumulation, DNA-damage, photosynthetic impairment and lipid peroxidation (Llorens et al., 2015). In response to these detrimental effects, plants have evolved an array of mechanisms to adapt to or defend against UV-B radiation, including strategies such as exposure limitation, protection, repair mechanisms, or a combination of these (Wada et al., 2003;Britt, 2004;Song et al., 2013). For example, plants synthesize UV-B absorbing compounds like flavonoids or develop specialized protective structures such as trichomes and bracts to reduce UV-B damage (Moles et al., 2020;Song et al., 2020). ...
... Ovules are typically shielded from solar radiation by the protective ovary, whereas pollen grains are often exposed, especially during the period between anther dehiscence and pollen tube penetration into the stigma (Proctor and Yeo, 1973;Feng et al., 2000;Llorens et al., 2015). Studies have reported that UV-B radiation can induce reductions in pollen germination and subsequent pollen tube growth, both in field and in vitro experiments (Feder and Shrier, 1990;Musil, 1995;Feng et al., 2000;Song et al., 2013;Zhang et al., 2014), ultimately leading to decreased seed yield (Teramura and Murali, 1986;Song et al., 2013). However, there are also reports indicating that UV-B radiation has no significant effect on pollen germination and tube growth. ...
... Ovules are typically shielded from solar radiation by the protective ovary, whereas pollen grains are often exposed, especially during the period between anther dehiscence and pollen tube penetration into the stigma (Proctor and Yeo, 1973;Feng et al., 2000;Llorens et al., 2015). Studies have reported that UV-B radiation can induce reductions in pollen germination and subsequent pollen tube growth, both in field and in vitro experiments (Feder and Shrier, 1990;Musil, 1995;Feng et al., 2000;Song et al., 2013;Zhang et al., 2014), ultimately leading to decreased seed yield (Teramura and Murali, 1986;Song et al., 2013). However, there are also reports indicating that UV-B radiation has no significant effect on pollen germination and tube growth. ...
Despite widespread recognition of pollen's potential sensitivity to ultraviolet-B (UV-B) radiation (280–315 nm), there remains ongoing debate surrounding the extent and mechanisms of this effect. In this study, using published data on pollen germination and tube growth including 377 pair-wise comparisons from 77 species in 30 families, we present the first global quantification of the effects of UV-B radiation on pollen germination and tube growth, along with its underlying mechanisms. Our results showed a substantial reduction in both pollen germination and tube growth in response to UV-B radiation, affecting 90.9 % and 84.2 % of species, respectively. Notably, these reductions exhibited phylogenetic constraints, highlighting the role of evolutionary history in shaping the sensitivity of pollen germination and tube growth to UV-B radiation. A negative correlation between elevation and the sensitivity of pollen tube growth was detected, suggesting that pollens from plants at higher elevations exhibit greater resistance to UV-B radiation. Our investigation also revealed that the effects of UV-B radiation on pollen germination and tube growth were influenced by a range of abiotic and biotic factors. Nevertheless, the intensity and duration of UV-B radiation exposure exhibited the highest explanatory power for the effects on both pollen germination and tube growth. This suggests that the responses of pollens to UV-B radiation are profoundly influenced by its dose, a critical consideration within the context of global change. In conclusion, our study provides valuable insights into the diverse responses of pollen germination and tube growth to UV-B radiation, highlighting the environment and species-dependent nature of pollen's susceptibility to UV-B radiation, with substantial implications for our understanding of the ecological and agricultural consequences of ongoing changes in UV-B radiation.
... Hu et al. (2022) studied the morphology of the structure and leaf surface of Rheum tanguticum in China. Song et al. (2013) studied the morphology of multifunctional bracts in Rheum nobile. Zhao et al. (2008) studied flower morphometry for Rheum rhaponticum. ...
Sumbembayev AA, Lagus OA, Nowak S. 2023. Seed morphometry of Rheum L. (Polygonaceae) species from Kazakhstan and its implications in taxonomy and species identification. Biodiversitas 24: 4677-4692. In the article, the evaluation of morphometric and weight parameters of seeds of 7 species of the genus Rheum L. from Kazakhstan is presented, as well as an analysis of their biometric parameters from different ecological and geographical habitats. The purpose of the study was to determine the variability of the seeds of the studied taxa and the importance of the results in determining the taxonomic relationships within the genus. The external structure was described for all species of the genus. Seeds of all studied species are illustrated with photos and scale drawings, and their features are summarized in a table. Stable and taxonomically significant features were identified for the species of the section Ribesiformia, represented by R. cordatum and R. maximowiczii, allowing their identification. The correlation between seed metric parameters and environmental conditions of the site and growth area was established and found a significant relationship between morphometric data and most of the environmental factors studied. The low adaptive potential of rhubarb species in Kazakhstan and the species' narrow ecological range were found. The comparison of the results obtained with the taxonomic relationships and phylogeny of representatives of the genus are briefly discussed.
... This giant herb occurs sparsely across subnival belts in the QTP at elevations between 4000 and 6000 m [5][6][7] and at flowering possesses stacked layers of large and showy bracts that securely conceal the entire inflorescence, to produce a pagodashaped 'glasshouse' phenotype ( Fig. 1b) 7,8 . These bracts aids reproduction in multiple ways 5,6,[9][10][11][12][13][14][15] , which could increasing flower and fruit temperature within bracts and that higher by up to 10 and 8°C, respectively 15 , than when bracts were removed or in the ambient conditions on sunny days, preventing pollen grains from being washed away by rain 9,15 , and intensity of ultraviolet-B (UV-B) radiation reaching flowers (or fruits) was decreased by 93-98% by bracts 5,11,15 , but there have been no previous attempts to investigate the genetic bases of subnival adaptation in these plants. Before flowering, plants develop for several years as a rosette during which they are subject to extremely low temperatures and strong winds, particularly during winter periods. ...
... This giant herb occurs sparsely across subnival belts in the QTP at elevations between 4000 and 6000 m [5][6][7] and at flowering possesses stacked layers of large and showy bracts that securely conceal the entire inflorescence, to produce a pagodashaped 'glasshouse' phenotype ( Fig. 1b) 7,8 . These bracts aids reproduction in multiple ways 5,6,[9][10][11][12][13][14][15] , which could increasing flower and fruit temperature within bracts and that higher by up to 10 and 8°C, respectively 15 , than when bracts were removed or in the ambient conditions on sunny days, preventing pollen grains from being washed away by rain 9,15 , and intensity of ultraviolet-B (UV-B) radiation reaching flowers (or fruits) was decreased by 93-98% by bracts 5,11,15 , but there have been no previous attempts to investigate the genetic bases of subnival adaptation in these plants. Before flowering, plants develop for several years as a rosette during which they are subject to extremely low temperatures and strong winds, particularly during winter periods. ...
... This giant herb occurs sparsely across subnival belts in the QTP at elevations between 4000 and 6000 m [5][6][7] and at flowering possesses stacked layers of large and showy bracts that securely conceal the entire inflorescence, to produce a pagodashaped 'glasshouse' phenotype ( Fig. 1b) 7,8 . These bracts aids reproduction in multiple ways 5,6,[9][10][11][12][13][14][15] , which could increasing flower and fruit temperature within bracts and that higher by up to 10 and 8°C, respectively 15 , than when bracts were removed or in the ambient conditions on sunny days, preventing pollen grains from being washed away by rain 9,15 , and intensity of ultraviolet-B (UV-B) radiation reaching flowers (or fruits) was decreased by 93-98% by bracts 5,11,15 , but there have been no previous attempts to investigate the genetic bases of subnival adaptation in these plants. Before flowering, plants develop for several years as a rosette during which they are subject to extremely low temperatures and strong winds, particularly during winter periods. ...
Subnival glasshouse plants provide a text-book example of high-altitude adaptation with reproductive organs enclosed in specialized semi-translucent bracts, monocarpic reproduction and continuous survival under stress. Here, we present genomic, transcriptomic and metabolomic analyses for one such plant, the Noble rhubarb (Rheum nobile). Comparative genomic analyses show that an expanded number of genes and retained genes from two recent whole-genome duplication events are both relevant to subnival adaptation of this species. Most photosynthesis genes are downregulated within bracts compared to within leaves, and indeed bracts exhibit a sharp reduction in photosynthetic pigments, indicating that the bracts no longer perform photosynthesis. Contrastingly, genes related to flavonol synthesis are upregulated, providing enhanced defense against UV irradiation damage. Additionally, anatomically abnormal mesophyll combined with the downregulation of genes related to mesophyll differentiation in bracts illustrates the innovation and specification of the glass-like bracts. We further detect substantial accumulation of antifreeze proteins (e.g. AFPs, LEAs) and various metabolites (e.g. Proline, Protective sugars, procyanidins) in over-wintering roots. These findings provide new insights into subnival adaptation and the evolution of glasshouse alpine plants.
... The remarkable glasshouse-like morphology was assumed to be essential for the plants to cope with low temperature and strong UV radiation at high elevation [8][9][10] . This adaptive trait has also been found to be important for the mutualism between the plants and the pollinating seed-consuming Bradysia fungus gnats, providing shelter for adult oviposition and larva development [11][12][13] . ...
... Genomic modification associated with adaptation to high elevations has been well documented in animals 15 but has been less explored in plants relative to the high diversity of alpine flora. But as iconic plants of the alpine landscape, glasshouse plants have become the focus of greater ecological and evolutionary interests 8,10,12,13,[16][17][18][19] . Studies on the ecological function of the specialized structures of alpine plants, such as cushion-like leaf canopy [20][21][22][23] , hairy leaves and inflorescences [24][25][26] , leafy bracts 8,12,13 , and nodding capitula 27,28 have revealed that these traits are particularly efficient in heat-trapping. ...
... But as iconic plants of the alpine landscape, glasshouse plants have become the focus of greater ecological and evolutionary interests 8,10,12,13,[16][17][18][19] . Studies on the ecological function of the specialized structures of alpine plants, such as cushion-like leaf canopy [20][21][22][23] , hairy leaves and inflorescences [24][25][26] , leafy bracts 8,12,13 , and nodding capitula 27,28 have revealed that these traits are particularly efficient in heat-trapping. For example, the temperature within the leaf canopy of the cushion plant Silene acaulis (L.) Jacq. is typically 15°C higher than the ambient temperature during clear summer days 20 . ...
Glasshouse plants are species that trap warmth via specialized morphology and physiology, mimicking a human glasshouse. In the Himalayan alpine region, the highly specialized glasshouse morphology has independently evolved in distinct lineages to adapt to intensive UV radiation and low temperature. Here we demonstrate that the glasshouse structure – specialized cauline leaves – is highly effective in absorbing UV light but transmitting visible and infrared light, creating an optimal microclimate for the development of reproductive organs. We reveal that this glasshouse syndrome has evolved at least three times independently in the rhubarb genus Rheum. We report the genome sequence of the flagship glasshouse plant Rheum nobile and identify key genetic network modules in association with the morphological transition to specialized glasshouse leaves, including active secondary cell wall biogenesis, upregulated cuticular cutin biosynthesis, and suppression of photosynthesis and terpenoid biosynthesis. The distinct cell wall organization and cuticle development might be important for the specialized optical property of glasshouse leaves. We also find that the expansion of LTRs has likely played an important role in noble rhubarb adaptation to high elevation environments. Our study will enable additional comparative analyses to identify the genetic basis underlying the convergent occurrence of glasshouse syndrome.
... f. & Thomson and R. alexandrae Batalin. The multifunctional translucent bracts of such plants are likely to have evolved independently in the Himalayas as a response to low temperatures and high irradiance, facilitating an upward range shift in response to climate change (Tsukaya and Tsuge, 2001;Tsukaya, 2002;Sun et al., 2012;Song et al., 2013c;Song et al., 2015;Song et al., 2020a). On the other hand, cold-adapted alpine plants may experience range contractions and/or local extinctions (Gimeńez-Benavides et al., 2011;Wiens, 2016) due to a slower rate of adaptation than that of climate change (Quintero and Wiens, 2013). ...
... Despite their relatedness and morphological similarity (Sun et al., 2012), they have distinct habitat and range distributions. Rheum nobile is found chiefly on alpine open scree and occasionally in open patches of alpine meadows, i.e., in well-drained habitats (Chowdhery and Agrawala, 2009;Song et al., 2013c), whereas the partly sympatric R. alexandrae is found mainly on alpine wetlands, including marshes, swampy meadows, and lakeshores (Chen, 1993). ...
Alpine plants’ distribution is being pushed higher towards mountaintops due to global warming, finally diminishing their range and thereby increasing the risk of extinction. Plants with specialized ‘glasshouse’ structures have adapted well to harsh alpine environments, notably to the extremely low temperatures, which makes them vulnerable to global warming. However, their response to global warming is quite unexplored. Therefore, by compiling occurrences and several environmental strata, we utilized multiple ensemble species distribution modeling (eSDM) to estimate the historical, present-day, and future distribution of two alpine ‘glasshouse’ species Rheum nobile Hook. f. & Thomson and R. alexandrae Batalin. Rheum nobile was predicted to extend its distribution from the Eastern Himalaya (EH) to the Hengduan Mountains (HM), whereas R. alexandrae was restricted exclusively in the HM. Both species witnessed a northward expansion of suitable habitats followed by a southerly retreat in the HM region. Our findings reveal that both species have a considerable range shift under different climate change scenarios, mainly triggered by precipitation rather than temperature. The model predicted northward and upward migration for both species since the last glacial period which is mainly due to expected future climate change scenarios. Further, the observed niche overlap between the two species presented that they are more divergent depending on their habitat, except for certain regions in the HM. However, relocating appropriate habitats to the north and high elevation may not ensure the species’ survival, as it needs to adapt to the extreme climatic circumstances in alpine habitats. Therefore, we advocate for more conservation efforts in these biodiversity hotspots.
... The leaf size of R. tanguticum is much larger than that of the large translucent bracts of the giant alpine plant Rheum nobile Hook. f. et Thomson [39,40]. As a result, the leaves of over-5-year-old R. tanguticum plants can be considered on record as one of the largest on the QTP. ...
Leaves are essential plant organs with numerous variations in shape and size. The leaf size is generally smaller in plants that thrive in areas of higher elevation and lower annual mean temperature. The Qinghai–Tibetan Plateau is situated at an altitude of >4000 m with relatively low annual average temperatures. Most plant species found on the Qinghai–Tibetan Plateau have small leaves, with Rheum tanguticum Maxim. ex Balf. being an exception. Here, we show that the large leaves of R. tanguticum with a unique three-dimensional (3D) shape are potentially an ideal solution for thermoregulation with little energy consumption. With the increase in age, the shape of R. tanguticum leaves changed from a small oval plane to a large palmatipartite 3D shape. Therefore, R. tanguticum is a highly heteroblastic species. The leaf shape change during the transition from the juvenile to the adult phase of the development in R. tanguticum is a striking example of the manifestation of plant phenotypic plasticity. The temperature variation in different parts of the leaf was a distinct character of leaves of over-5-year-old plants. The temperature of single-plane leaves under strong solar radiation could accumulate heat rapidly and resulted in temperatures much higher than the ambient temperature. However, leaves of over-5-year-old plants could lower leaf temperature by avoiding direct exposure to solar radiation and promoting local airflow to prevent serious tissue damage by sunburn. Furthermore, the net photosynthesis rate was correlated with the heterogeneity of the leaf surface temperature. Our results demonstrate that the robust 3D shape of the leaf is a strategy that R. tanguticum has developed evolutionarily to adapt to the strong solar radiation and low temperature on the Qinghai–Tibetan Plateau
Keywords: Rheum tanguticum; Qinghai–Tibetan Plateau; phenotypic plasticity; heteroblasty; 3D leaf shape; leaf-surface temperature; leaf thermoregulation
... Many flowering plants have evolved distinctive floral traits to ensure reproductive success (Lloyd and Barrett 1996;Song et al. 2013;Sun and Huang 2015). The evolution of floral traits is shaped by various selection forces, including pollinators, biotic nonpollinators and abiotic factors (Waser and Price 1983;Nilsson 1988;Herrera 1997;Herrera et al. 2003;Strauss and Whittall 2006;Sun et al. 2008;Yang and Sun 2009;Li et al. 2021). ...
... Therefore, shortening of the calyx may alter the fruit growth micro-environment. Changes in the microenvironmental factors (such as light and temperature) can have adverse effects on fruit development (Polowick and Sawhney 1985;Adams et al. 2001;Song et al. 2013;Reale et al. 2019). Third, calyx sepals are a significant source of assimilates for the developing seeds and fruits (Vemmos and Goldwin 1994;Smillie et al. 1999;Salopek-Sondi et al. 2000;Aschan and Pfanz 2003;Herrera 2005). ...
The evolution of persistent calyces may be an adaptation to ensure reproductive success of certain flowering plants. However, experimental evidence of the functions of persistent calyces during flowering and seed development remains scarce. We explored the possible functions of persistent calyces in Salvia miltiorrhiza, a perennial herb with campanulate calyx. We conducted calyx manipulation experiments to examine whether persistent calyces affect visitation rates of nectar robbers and pollinators, individual flower longevity, fruit set, seed set and seed mass. Our findings suggested that shortening of the calyx significantly decreased individual flower longevity, fruit set and seed mass, but did not affect visitation of pollinators and nectar robbers. In addition, the seed set of control flowers and the flowers with calyx shortened at the beginning of fruiting stage (CSF flowers) did not significantly differ, but both were higher than that of the flowers with calyx shortened at the beginning of blooming stage (CSB flowers). The seed set and fruit set of CSB flowers were limited by pollination due to the reduction in floral longevity. We conclude that persistent calyces of S. miltiorrhiza may represent adaptive strategies to maintain floral longevity and increase plant fitness. Persistent calyces may provide protection for the growth of flowers and contribute resources to the development of fruits and seeds.
... Plant reproductive systems could have involved strategies to cope with environmental stresses such as low temperature. For instance, large and showy translucent bracts in Rheum nobile (Polygonaceae), which usually grows near the snow line, could function to conceal the whole compound racemes and persist until the seeds have ripened, maintaining a relatively warm room for both seeds and pollinating parasitic flies (Song et al., 2013(Song et al., , 2015; furthermore, the bracts were recently suggested to screen UV light (Song et al., 2020). Bracts covering the inflorescences of Saussurea (Asteraceae) species growing at high elevations, endemic to the QTP-HMR, could increase the daytime temperature (2.5°C) within the bracts (Tsukaya et al., 2002;Yang & Sun, 2009;Semwal et al., 2019). ...
