Flora最新文献

Rourea chrysomalla is a rare and endemic plant species from the Brazilian Cerrado, presumably threatened and lacking records within conservation units. In this study, we recorded and characterized, for the first time, the floral and pollen dimorphism, as well as the reciprocity of sexual organs among different morphs of R. chrysomalla. For this purpose, fertile individuals were observed over three years in two natural populations and supplemented by herbarium data. This species is distylous and distinctly exhibits two types of flowers, each characterized by stamens arranged in two whorls of unequal lengths: L-styled and S-styled morphs, both occuring in similar proportions in the two populations. Cross-pollination among anthers of any stamen whorl in L-styled flowers and stigmas in S-styled flowers is more precise in the two morphs, while anthers in S-styled flowers are less reciprocal with the stigmas in L-styled flowers. S-styled flowers exhibit larger pollen grains compared to L-styled flowers, with no differences between the two whorls of stamens. The balanced proportion of floral morphs provides equal opportunities for pollen donation and reception, and reciprocity between morphs is essential for the conservation of R. chrysomalla due to its limited distribution and low population density in the central Brazilian savanna.

Cocoa (Theobroma cacao L.) is an important crop, but yield is generally low. Improving yield requires detailed understanding of the reproductive ecology, especially the pollination system and factors determining pollination success, such as proximity to natural areas. Since the 1940s biting midges have been proposed as the pollinators of cocoa flowers but this idea has recently been questioned in various studies. We observed cocoa flowers and their visitors during anthesis, we compare cocoa flower visitors during the day and night and also in plantations connected and disconnected to natural forests. Observations of flowers during anthesis revealed that cocoa flowers are protandrous, open at night, persist for three days and are receptive only during the day. A diversity of insects visited flowers throughout 24 h. In general, insect visitors were more diverse during the day and in plantations connected to forests compared to those not connected to forests. Fifty five percent of the total insect species visited the cocoa flowers at night, all insect species visited cocoa flowers in plantations connected to natural forests and 62.5 % of those visited cocoa flowers in plantations disconnected with forests. Hymenoptera and Diptera were the main visitors and a total of eleven insect species carried cocoa pollen grains. Among those, two species of biting midges (Ceratopogonidae flies) and two species of stingless bees (Meliponini bees) were the most common. While biting midges were the most common visitors, the stingless bee Tetragonisca angustula carried large cocoa pollen loads and interacted with both the male and female parts of the flower. Ants also visited cocoa flowers, mainly at night. The most common visitors of cocoa flowers in cocoa plantations in the upper Magdalena Valley in Colombia are diurnal biting midges and stingless bees, but also nocturnal ants, suggesting that the pollination system of cocoa flowers may be locally less specialized than previously thought. Future research should investigate the effectiveness of various insect groups as pollinators.

Variation in the quantity and quality of reward substances produced by flowers influences reproductive success in angiosperms. In this study, a comparative analysis of nectaries and nectar traits (volume, concentration and sugar composition) was performed on the hybrid Cephalocereus columna-trajani × C. tetetzo and its parental species to identify phenotypic variation that could affect reproductive success. The presence of nectarostomata and two types of nectary cells are significant, as well as the presence of xylem and phloem. Furthermore, possible interspecific differences in the amount of starch and mucilage may be relevant. Interspecific variation in nectar volume and concentration was found, with the hybrid exhibiting the highest concentration. All three taxa presented hexose-dominated nectar. In conclusion, C. columna-trajani × C. tetetzo, like its parental species has a functional and anatomically well-formed nectary. Differences in traits such as the amount of starch and mucilage associated with nectar volume, in combination with differences in nectar concentration could have potential consequences for fitness. Our results confirm previous reports on the development of functional structures in hybrid flowers and serve as the basis for future studies testing whether the differences observed here govern the dynamics of competition in hybridization zones.

In subtropical grasslands, characterized by the coexistence of species with different physiology, for example C3 and C4 grasses, studies on the reproductive patterns of plants at the community level are scarce. Most available studies are limited to plant-pollinator interactions, and do not include grasses, even though knowledge on phenology of this species group is highly relevant, e.g., for grazing management or ecological restoration. In this study, we monthly evaluated flowering and fruiting in Brazilian subtropical grasslands under different grazing intensities (high, moderate, low, very low, ungrazed) over one year. To estimate the effect of the seasonal variation on the phenology of functional groups (C3 grass, C4 grass, monocots, dicots, shrubs) we used circular statistics. The highest flowering activity occurred in October and November, while fruiting peaked in March and April. Shrubs had the highest number of flowers and fruits, and C4 grasses contributed the largest number of fruiting species. The flowering peak of most functional groups occurred in October, except for C4 grasses and shrubs that peaked in February and November, respectively. Fruiting of C3 grasses peaked in December, C4 grasses and shrubs were most abundant in April and dicots, and monocots peaked in October. Grazing treatments differed considerably in flowering and fruiting patterns for all species groups. Monocots and dicots herbs showed high flowering activity under intense grazing. C3 grasses presented highest peaks in moderate and low grazing intensities, while C4 grasses peaked in very low grazing, and shrubs showed the highest peaks in ungrazed plots. Flowering and fruiting occurred throughout the year in our study system, with clear variation among functional groups in response to climatic and management patterns. Our results can guide seed collection in the field or vegetation cutting for hay transfer, and thus should lead to improvements in the ecological restoration of subtropical grasslands.

Functional biogeography is the discipline that studies the geographic distribution of organismal traits and their relationships with environmental conditions and ecosystem functioning. Trait multifunctionality can be a major challenge in such analyses, so deciphering trait geographic distributions from functions is not always straightforward. We studied spinescence in the flora of Israel and the Palestinian Authority as a case of a multifunctional trait, associated mainly with antiherbivory defence, aridity alleviation, and propagule and seed dispersal. We studied how the proportion of spiny species in the flora of Israel and the Palestinian Authority and the distribution of different spine locations within the plants vary along a very strong bioclimatic (especially rainfall) gradient in Israel and the Palestinian Authority. We found that plant spinescence, as expressed in species proportion, is more frequently positively associated with increasing aridity and summer heat, and more generally with resource limitations. However, spinescence of reproductive plant parts, which in many species aids seed dispersal, presents opposite trends. These patterns reflect the differing importance of each of the three major roles attributed to plant spinescence, and point to the relative importance of each in driving overall spinescence geographic distribution. Thus, the traits’ geographic distribution patterns can elucidate these traits’ multifunctionality and improve our understanding of the evolution and spatial variation among these functions.

The ligule is an important character in the taxonomic delimitation of Selaginella species. Here, the morphology of this organ is described in 11 American species. Four of these species are xerophytic: Selaginella convoluta, S. microphylla, S. peruviana, and S. sellowii, and seven are mesophytic: S. anceps, S. diffusa, S. flagellata, S. flexuosa, S. mollis, S. silvestris, and S. sulcata. Morphological data were obtained by traditional histological techniques. Observations were made by light and scanning electron microscopy. Variations in ligule size in vegetative leaves and sporophylls were determined using a correlation analysis with Spearman's coefficient. The ligule was found to have five body shapes: campanulate, linguiform, elliptic, fan-shaped, and rectangular. Each shape can have a lobed (bi-, tri-, or multi-lobed), rounded, or truncate apex. Size, shape, and apex are characteristic of each species and remain constant in young and mature leaves. No significant differences were observed between xerophytic and mesophytic species. The ligule of all species studied is described for the first time. Micrographs of all the species studied are presented, and the morphological results of this study have been mapped into the recent phylogeny of the genus.

Eleutherococcus senticosus (Araliaceae) is widely used as adaptogen in herbal medicine. Since comprehensive anatomical analysis of its vegetative organs was not available, the present study aimed at providing the reference data on the structure of leaves and roots, under- and aboveground stems of 1–4 year-old plants by means of conventional light microscopy. In the primary structure, roots were di- or triarch, with secretory canals facing protoxylem. Concurrently with cambium initiation, additional pericyclic secretory canals differentiated close to the existing ones. In the root secondary structure, secretory canals were formed in the conductive secondary phloem and maintained in the nonconductive one. Stem primary structure encompassed uniseriate epidermis with scant prickles, primary cortex and stele. Primary cortex was composed of collenchyma, chlorenchyma, ground parenchyma with secretory canals and ca. triseriate starch sheath. In outer stele (pericycle) strands of sclerenchyma fibers (stereids) differentiated, alternated with parenchyma. In the ring of open collateral bundles, cambium became continuous concurrently with (sub)epidermal initiation of phellogen. In the wide pith, ground parenchyma occurred, with a few secretory canals close to protoxylem. Secondary structure stems retained the cortical tissues in the 4th year; new secretory canals appeared in the conductive secondary phloem. The epithelial cells/sheath cells complexes were maintained even in the oldest nonconductive phloem (and in the cortex) in stems of 4 year-old plants, while the successively formed sieve tube-companion cell complexes functioned till the end of the vegetation periods only. The bifacial leaves exhibited shade adaptation in chlorenchyma structure; secretory canals were formed mainly in veins’ phloem.

The Canga vegetation in Brazil is a unique ecosystem found on ironstone outcrops, known as ferruginous rupestrian fields, and is considered one of the most diverse in the world. This mosaic landscape, comprised of trees, shrubs, and herbaceous vegetation, is home to a diverse range of plants, including angiosperm, bryophytes, and lichens. To understand the effect of Cangas' patchy landscape, here called mesohabitats, on bryophyte communities, we asked the following questions: Do the diversity parameters such as richness, abundance and composition of bryophytes differ along the different Cangas’ mesohabitats? Do bryophyte assemblages group by functional traits and filter per mesohabitat? We surveyed eight sites in the Quadrilátero Ferrífero (Iron Quadrangle), southeast Brazil. We collected and analysed data on bryophyte diversity and functional traits in three different mesohabitats: exposed areas (EA), shrub associations (SA), and tree associ ations (TA). The diversity of both groups was tested using one-way ANOVA; and functional traits were addressed with a Factorial Analysis of Mixed Data (FAMD). There are significant differences in the diversity of bryophytes among the mesohabitats, with TA having the highest diversity and abundance of liverworts and mosses, followed by SA and EA. The study also found bryophyte assemblies with similar functional traits in similar mesohabitats across the Brazilian Quadrilátero Ferrífero. The research revealed that the different mesohabitats provided important and distinct niches for bryophytes in Cangas, and this threatened ecosystem's high diversity must be considered when developing conservation strategies. This entails land managers adopting effective approaches aimed at improving both the quality and connectivity of habitats, fostering biodiversity, and bolstering the resilience of the ecosystem.

In the arid landscapes of South Morocco's Saharan fringe, traditional agroecosystems stand out for their rich diversity of segetal vegetation. This study examines the segetal flora of these unique agroecosystems, investigating their richness, community characteristics and composition. We collected 155 relevés in fields located in the Guelmim province comprising three agroecosystem types: Oases, terraced and floodplain fields (faïd). We found 221 vascular plant species including seven regional endemics and one nationally very rare species. Using TWINSPAN, we identified three plant communities, each restricted to a specific agroecosystem type, displaying differences in species composition, floristic status, life-form and biogeographical spectra. Oasis vegetation had the highest overall number of species, terraced fields had the highest diversity, and therophytes were dominant across all communities, with faïds being the most therophyte-rich. The pan-Mediterranean chorotype dominated all three community types. Apophytes dominated, particularly in faïd and terraced fields, surpassing oasis fields rich in ruderals. We found that traditional cereal agroecosystems in southern Morocco harbor species-rich segetal plant communities created by habitat-based land-use systems. Our results highlight the significance of agricultural practices and local abiotic factors in shaping the agroecosystems, which are adapted to arid environments and sensitive to environmental and social changes.

Marrubium cuneatum is an endemic Iranian plant species, which can be found in lead-contaminated environments. This study aimed to investigate the effects of lead on the growth and germination in two M. cuneatum populations, from metalliferous, Pb-contaminated and uncontaminated soil, respectively. Soil and plant samples of the Tang-e Douzan Pb-Zn mine and Morghab Spring (non-contaminated site) were collected and analysed. Germination and growth were recorded under increasing Pb exposure in the non-metallicolous (NM) and the metallicolous (M) local M. cuneatum populations. Germination percentage (GP), mean germination time (MGT), germination index (GI), healthy plant percentage (HPP), seedling death (SD), fresh weight (FW) and dry weight (DW), were measured. Primary assessments showed toxic levels of lead in soil samples of the Tang-e Douzan mine and in leaves of plants growing at the mine site. Germination experiments showed that the germination parameters were stimulated by low concentrations of Pb in both populations, but inhibited by high concentrations. However, the adverse effects of Pb at high concentrations on GP, GI, and HPP were significantly less in the M population. The mortality of germinating seeds (SD) was consistently associated with fungal infection, which gradually decreased with increasing Pb exposure, but to the same degree in both populations. Growth experiments clearly demonstrated Pb hypertolerance in the M population. In the NM population, seedling growth is more sensitive to excess Pb than seed germination, compared to the M population. The M population has high biomass and a relatively high Pb accumulation in its shoots, which suggests it is a suitable candidate for phyto-extraction of Pb.