Pollination adaptations of group-by-group stamen movement in a meadow plant with temporal floral closure

Floral sexual organ (stamen and pistil) movements are selective adaptations that have different functions in male-female reproduction and the evolution of flowering plants. However, the significance of stamen movements in the spatial-temporal function and separation of male and female organs has not been experimentally determined in species exhibiting floral temporal closure. The current study investigated the role of slow stamen (group-by-group) movement in male-female sexual function, and the effect of stamen movement on pollen removal, male-male and male-female interference, and mating patterns of Geranium pratense, a plant with temporal floral closure. This species uses stamen group-by-group movement and therefore anther-stigma spatial-temporal separation. Spatial separation (two whorls of stamen and pistil length) was shown to be stronger than temporal separation. We found that stamen movements to the center of the flower increase pollen removal, and the most common pollinators visited more frequently and for longer durations during the male floral stage than during the female floral stage. Petal movements increased both self-pollen deposition rate and sexual interference in G. pratense. The fruit and seed set of naturally and outcrossed pollinated flowers were more prolific than those of self-pollinated flowers. Group-by-group stamen movement, dehiscence of stamens, pistil movement, and male-female spatial-temporal functional separation of G. pratense before floral temporal closure may prevent male-female and stamen-stamen interference and pollen discounting, and may increase pollen removal and cross-pollination.

Documenting the heritage along the Silk Road: An ethnobotanical study of medicinal teas used in Southern Xinjiang, China

ETHNOPHARMACOLOGICAL RELEVANCE

People in Southern Xinjiang, China have been consuming medicinal teas for healthcare since before the ancient Silk Road markets began. Several pharmaceutical studies have illustrated the potential healthcare benefits of medicinal teas used in Southern Xinjiang, China. However, little information is available from the literature about the diversity of the species used and related traditional knowledge of these medicinal teas.

AIMS OF THE STUDY

(i) create a comprehensive record of medicinal tea plant species (MTPS) and combinations used with related traditional knowledge for healthcare in Southern Xinjiang, China; (ii) assess safety of MTPS, and (iii) address conservation status for sustainable use of MTPS.

MATERIALS AND METHODS

We employed both field and market surveys from 2014 to 2019 in 10 counties/cities and four main medicinal tea markets by using semi-structured interviews. We interviewed 236 informants and 70 medicinal tea shop vendors. The commonly used MTPS were ranked by Frequency of Citation. Safety issues were assessed based on expert knowledge and with reference to the official list of Medicinal Plants Used as Food. Conservation implications of plant use were assessed as part of the interviews and this was cross referenced with official records.

RESULTS

The surveys revealed 145 different plants from 65 families used for making medicinal teas, expanding the list of known Chinese herbal tea species from 782 to 884. Leguminosae, Rosaceae, Lamiaceae and Apiaceae were dominant families. Herbs (60.7%, 88 species) were the most commonly used plant types; fruits (23.1%, 50 species) and seeds (22.2%, 48 species) were commonly used parts. Nearly half (42.1%) of the plant species were introduced from abroad. Respondents reported more than 50 types of healthcare uses of medicinal teas. Tonic (13.7%, 71 species) and promoting digestion (9.6%, 50 species) were the most frequently mentioned healthcare uses. The majority of commonly used plant species were spices (20 species, 50%) and aromatic plants (10 species, 25%). Cinnamomum cassia (L.) J.Presl, Piper longum L. Syzygium aromaticum (L.) Merr. & L. M. Perry and Gardenia jasminoides J. Ellis were the most cited species. High doses of Piper longum L., Crocus sativus L., Curcuma longa L, and Senna alexandrina Mill. May have negative health implications. Assessments of conservation status and sustainable use of tea species indicate that wild harvesting of Nardostachys jatamansi (D. Don) DC. and Pterocarpus indicus Willd. Should be controlled and cultivation technologies should be improved.

CONCLUSIONS

We found high plant species diversity and rich traditional knowledge of medicinal teas used in Southern Xinjiang, China. The traditional healthcare uses of some of the medicinal teas are also supported by pharmaceutical evidence. Others should be investigated further. Conservation pressures exist for commonly used wild species. China's 'Healthy China 2030' policy should do more to take traditional cultural practices into account. In doing so, both local and national government agendas may seek to promote sustainable harvest and to protect traditional knowledge so that this cultural heritage continues to serve human well-being into the future.

Elevation-related variation in the population characteristics of distylous Primula nivalis affects female fitness and inbreeding depression

The population characteristics of distylous species are highly sensitive to stochastic natural selection pressure. Therefore, populations growing under different environmental conditions may vary in floral morph ratios, potentially affecting female fitness and leading to inbreeding depression. However, the variation in offspring quality among populations as a result of inbreeding depression is poorly understood in distylous species. This study investigates variations in plant density, seed mass, seed viability, female fitness, and post-dispersal inbreeding depression in both sexual morphs (long-styled and short-styled plants) of the distylous Primula nivalis that were subjected to different pollination treatments along an elevational gradient from 1657 to 2704 m a.s.l. Population characteristics (morph plant density and ratio) and fruit set were significantly affected by sexual morph and elevation. Plant density and fruit set frequencies were lower for short-styled than for long-styled plants at 2704 m a.s.l. The seeds from the cross-pollinated flowers of both morphs were higher in quality than those of self-pollinated flowers. The female fitness of seeds from cross-pollinated flowers of both morphs was higher than that of seeds from open-pollinated and self-pollinated flowers. The female fitness of seeds from long-styled flowers was higher than that of seeds from short-styled flowers at all elevations. Inbreeding depression increased with elevation among plants with short-styled flowers but not among those with long-styled flowers. Variation in the elevation-dependent mating system might influence female fitness and affect inbreeding depression in both floral morphs. In conclusion, the low quality of seeds from short-styled flowers at high elevations might decrease short-styled flower frequency, affecting population characteristics.

Morphological plasticity and adaptation level of distylous Primula nivalis in a heterogeneous alpine environment

Plant populations at high elevation face extreme climatic conditions and resource limitations. The existence of distylous species at different elevations can help us investigate their adaptation to high altitudes, the evolution of their morphological characteristics, as well as their responses to limited resources. Here, 17 populations of Primula nivalis at different elevations were evaluated regarding variations in plant morphological characteristics, biomass allocation, and morphological plasticity in a heterogeneous environment. Our results demonstrate that heterogeneous environments can affect plant morphological characteristics and resource allocation in each sexual morph of these plants. Moreover, environmental variations reduced morphological plasticity in the two plant morphs, and the plasticity of long style (LS) plants was greater than that of short style (SS) plants. There were significant negative correlations between morphological characteristics and elevation, rainfall, temperature, and sunshine, and these are the main variables that affect morphological characteristics and resource allocation of both morphs of P. nivalis plants in heterogeneous environments. The morphological characteristics of P. nivalis plants transplanted from high to lower elevations were not significantly different in either population. LS plants had greater morphological plasticity and adaptability in heterogeneous environments than SS plants. Elevational gradients and heterogeneous environments differentiated both morphs of P. nivalis plants with regards to morphology as well as adaptations. LS plants showed a higher level of adaptability than SS plants.

Sexual expression and reproductive output in the ephemeral Geranium transversale are correlated with environmental conditions

PREMISE OF THE STUDY

Abiotic environmental factors are often considered to be important in the distribution and maintenance of variation in sexual systems in flowering plants. Associations between sexes and abiotic factors are well documented in dioecious systems, but much less is known about this relationship in other sexually polymorphic systems. Species that are highly variable in sexual expression and habitat distribution can provide insights into the role of abiotic factors in maintaining variation in sexual expression.

METHODS

Focusing on a sexually polymorphic species, Geranium transversale, we measured sexual expression at both the flower and the plant level and examined vegetative and floral traits, pollen deposition, and reproductive success. We also tested for correlations between sexual expression and other traits and examined whether and how these traits covaried with abiotic environmental conditions.

KEY RESULTS

We identified unique variation of sexual expression in G. transversale. There are four sexual morphs that display different combinations of the three flower types (pistillate, staminate, and perfect). Sexual morphs that are phenotypically more female (i.e., female and gynomonoecious morphs) are found in wetter and milder environments, and flower earlier than morphs that are more male (i.e., hermaphroditic and andromonoecious morphs). Additionally, floral organ size and reproductive success are influenced not only by the flower type but also by the sexual morph of the plant.

CONCLUSIONS

Environmental conditions are likely to cause some of the variation in sexual expression found in G. transversale. Both genetic and ecological factors likely contribute to the maintenance of sexual variation in this species.

Out of Africa: evidence of the obligate mutualism between long corolla tubed plant and long-tongued fly in the Himalayas

Mutualism between long corolla tubed plants and their potential pollinators, long-tongued flies, is a classic example of coevolution, but to date, has only been reported from the regions of southern Africa. Many plant species from the Himalayas also show botanical characteristics that could be consistent with pollination by long-tongued flies. Here, we seek the evidence of the "long-tongued-long tubed fly/flower" mutualism out of Africa, in a different continent and climatic region, the Himalayas.Floral traits of Himalayan region endemic alpine genus, Roscoea, indicate possible mutualism with long-tongued flies for pollination success; however, effective pollinators of this genus are yet unknown. This study investigates whether long-tongued flies and Roscoea purpurea in Nepal Himalayas show exclusive mutualism for their survival/reproduction.We made extensive observations of floral visitors of R. purpurea and food source of Philoliche longirostris across their wide ranges of populations in Nepal Himalayas for three consecutive years (2012-2014). To confirm the obligate reliance of R. purpurea upon P. longirostris for pollination success, manipulated pollination experiments were conducted at two populations for 2 years. Similarly foraging behavior, visitation frequency, and pollination efficiency of P. longirostris were assessed at two populations for 2 years, and its contribution for the reproductive success of R. purpurea was evaluated. Our results indicate that R. purpurea is self-compatible but lacks autonomous selfing and obligatorily relies on P. longirostris for reproductive success. Across all populations, P. longirostris was observed as an exclusive and highly efficient pollinator of R. purpurea, while P. longirostris exclusively depends up on R. purpurea for food source.Out of Africa, this study provides the first evidence of long-tongued fly pollination system and indicates the possibility of additional instances of such a rare phenomenon in the Himalayas. Finding of specialized pollinator of Roscoea only at its evolutionary center indicates that Roscoea species are originally pollinated by long-tongued flies. Spatial mismatch with specialized pollinators may have induced the evolution of autonomous selfing in North Indochinese clades of Roscoea. This finding thus substantiates how geographic disjunction causes the shifting of pollination mechanism in closely related plant species.