Inflorescence Type Research Articles

Assessment of Production and Qualitative Characteristics of Different Populations of Salvia sclarea L. Found in Sicily (Italy)

Salvia sclarea L. is an important industrial crop, valued for its herbal-aromatic properties and high quality essential oils, that is used in food, pharmaceuticals and cosmetics. In this study, carried out from 2009 to 2010, the morphological and production characteristics and essential oil content and composition of three Sicilian populations were studied. In particular, the composition of essential oils extracted from primary and secondary inflorescences using steam distillation was assessed. Morphological, production and qualitative data from the three populations were subjected to analysis of variance and cluster analysis. Regarding the quality of the oils, only the most prevalent compounds were taken into consideration in this study. The three populations were linalyl acetate/linalool chemotypes. Highly significant variations were found for the effective local population and inflorescence type in the composition of the essential oil principal components. In particular, the primary inflorescences were found to be accumulation sites favoured by monoterpenes, and secondary inflorescences were favoured by sesquiterpenes and sclareol. Populations “S. Stefano Quisquina” and “Alcara Li Fusi” performed best on a morphological and production level, whereas populations “Prizzi”and “Alcara Li Fusi” performed best in terms of quality. Population “S. Stefano Quisquina” produced high levels of sclareol. Biotype selection from within the populations should be based on both morphological, production and quality analyses.

A new species of Phyllagathis (Sonerileae, Melastomataceae) from Guangxi, China

Phyllagathis elegans (Melastomataceae, Sonerileae), a new species from Dongxing County in southern Guangxi, China, is described and illustrated. It closely resembles P. ovalifolia in habit, inflorescence type, floral merosity, stamen and capsule morphology, and crystal form, but differs from the latter in the hirsute stem with crooked hairs (vs. retrorse hairs), distally densely (vs. sparsely) leafy branches, and leaf blades 3-veined (vs. 5–7-veined), oblanceolate or elliptic-lanceolate (vs. ovate, oblong-ovate, or broadly elliptic).

Transferability of ISSR, SCoT and SSR Markers for Chrysanthemum × Morifolium Ramat and Genetic Relationships Among Commercial Russian Cultivars.

Characterization of genetic diversity in germplasm collections requires an efficient set of molecular markers. We assessed the efficiency of 36 new SCoT markers, 10 new ISSR markers, and 5 microsatellites for the characterization of genetic diversity in chrysanthemum core collection of 95 accessions (Russian and foreign cultivars). Seven new SCoT (SCoT12, 20, 21, 23, 29, 31, 34) and six new ISSR markers ((GA)8T, (CT)8G, (CTTCA)3, (GGAGA)3, (TC)8C, (CT)8TG) were efficient for the genetic diversity analysis in Chrysanthemum × morifolium collection. After STRUCTURE analysis, most Russian cultivars showed 20–50% of genetic admixtures of the foreign cultivars. Neighbor joining analysis based on the combination of SSR, ISSR, and SCoT data showed the best accordance with phenotype and origin compared to the separate analysis by each marker type. The position of the accessions within the phylogenetic tree corresponded with the origin and with some important traits, namely, plant height, stem and peduncle thickness, inflorescence type, composite flower and floret types, flower color, and disc color. In addition, several SCoT markers were suitable to separate the groups distinctly by the phenotypical traits such as plant height (SCoT29, SCoT34), thickness of the stem and peduncle (SCoT31, SCoT34), and leaf size and the floret type (SCoT31). These results provide new findings for the selection of markers associated with important traits in Chrysanthemum for trait-oriented breeding and germplasm characterization.

Plant biodiversity in residential yards is influenced by people’s preferences for variety but limited by their income

Residential yards are a unique component of the urban environment and harbor high cultivated plant biodiversity; however, why and how people create yards with so many plant species is not well understood. To investigate this pattern, we studied the relationships between residents’ preferences, income, and yard plant biodiversity in the Salt Lake Valley, Utah, USA where most of the urban vegetation is intentionally cultivated. We conducted in-person interviews, distributed written surveys, and inventoried the biodiversity (i.e., genus and species richness) of ornamental herbaceous flowering plants and lawn plants in residential yards located in neighborhoods across income levels. We found that 95% of surveyed residents valued having ‘plants that create variety in the yard’ (‘variety’ left open to interpretation) and that 47% of interviewed residents expressed an emotional connection to variety. On average, general plant variety was more important to residents than high plant biodiversity (i.e., a specified type of variety), but they also exhibited a preference for neat monoculture lawns lacking in biodiversity and other types of variety. Residents’ preferences for general plant variety, and biodiversity specifically, were not necessarily reflected in their yards. Higher income households had greater flowering plant variety in terms of number of different flower colors, inflorescence types, and genera, but lower lawn species biodiversity due to a reduction in weedy species. Overall, our study shows that most residents in this region prefer plant variety in their yards more than biodiversity specifically, and that people with higher incomes can better achieve these preferences.

Can plastome data resolve recent radiations?Rhodiola(Crassulaceae) as a case study

AbstractRecent radiations provide excellent models to gain more insights into evolution, speciation and adaptation. To this end, a well-resolved phylogenetic tree is needed. However, resolving phylogenetic relationships within recent radiations has been difficult as traditional phylogenetic markers failed to provide enough information. We here use plastome data to test their capacity in resolving phylogenetic relationships among a recent rapidly diverging group, Rhodiola, on the Qinghai-Tibetan Plateau. We reconstructed a robust phylogenetic backbone of Rhodiola using 23 plastomes representing all subgenera and sections in previous taxonomic treatments. Based on the backbone, we inferred the spatio-temporal pattern of diversification of the genus. We also traced evolution of five important morphological characters of Rhodiola, including sexual system, inflorescence type and flowering stem, based on the maximum likelihood and the threshold models. Two well-supported clades were revealed in Rhodiola, and the two clades were distinguished by sexual system: species in clade I are mostly hermaphrodite (except R. stapfii and R. integrifolia), and those in clade II are all dioecious. Biogeographic analysis showed that Rhodiola probably originated in the Qinghai-Tibetan Plateau and the Hengduan Mountains. The two major clades diverged c. 6.34 Mya, corresponding to a period of rapid uplift of the Hengduan Mountains and intensification of the Asian monsoon. Character evolution analysis confirmed parallel evolution of dioecy and other adaptive traits, such as marcescent flowering stems, in the genus. We demonstrate that plastome data could significantly improve phylogenetic resolution in plant groups resulting from recent radiations. Our results not only shed new light on the evolutionary history of Rhodiola, but also indicate that more plastome data should be used in resolving phylogenetic relationship in plant groups that have undergone recent radiations.

Millettia puerarioides Prain (Fabaceae: Millettieae), a species with cauliflorous inflorescences newly recorded from China

Millettia puerarioides Prain within the tribe Millettieae (Fabaceae) is a poorly known species and it was previously reported only from Myanmar. This species was recently found also in Yingjiang, Yunnan Province, China. The inflated pods with large seeds place it in Millettia section Macrosperma Dunn, but specimen examination and field investigations showed that it has inflorescences arising from leafless nodes and directly from the trunk (i.e. rami- and caulinascent inflorescences), which is similar to the species in the genus Fordia from the same tribe. This inflorescence type has been considered to be a rare character for Asian plants of the subfamily Papilionoideae, showing the close connection between Millettia and Fordia.

Experience of introduction of Chrysanthemum coreanum varieties of Ukrainian breeding in Central Botanical Garden of the National Academy of Sciences of Belarus

The main goal was primary comprehensive assessment of the biological and decorative indicators of varieties of chrysanthemum (Chrysanthemum coreanum (H. Lèv. & Vaniot) Nakai ex T. Mori), ukrainian selection of National Botanical Garden named after N. N. Grishko, for definition the possibility of their using for flower decoration of cities and other settlements of Belarus. Phenological observations were carried out during all vegetation periods from 2010 to 2020. The types of inflorescences of chrysanthemums were classified according to the generally accepted classification, which was developed for the chrysanthemum by the Dresden Institute of Horticulture (Clauss, 1960). Primary comprehensive assessment of chrysanthemum varieties was carried out according to the modified method of varietal assessment of the Central Scientific Center of the National Academy of Sciences of Belarus, which based on 11 biological and decorative indicators: color stability of the inflorescence, number of inflorescences on one shoot, height and shape of the plant, leafiness of the shoot (stem), winter hardiness, resistance to diseases and pests , vegetative mobility, annual stability of flowering, duration of flowering, longevity in culture. In article are given the results of the introduction of varieties of chrysanthemum breeding NBG named after N. N. Grishko collection of the Central Botanical Garden of the National Academy of Sciences of Belarus. Primary comprehensive assessment of 76 varieties of Korean chrysanthemum. The 31 varieties of chrysanthemums were selected, which can be recommended for flower decoration of cities and towns of Belarus. Thus, investigated varieties of Korean chrysanthemum, breeding NBS named after N. N. Grishko, characterized by a steady rhythm of seasonal growth and development. The majority varieties is going through all stages of seasonal development during the growing season, which indicates their successful adaptation to the climatic conditions of Belarus.

A new species of Phyllagathis (Melastomataceae, Sonerileae) from Guangxi, China

Phyllagathis impressinervia (Melastomataceae, Sonerileae), a new species from northwestern Guangxi, China and previously misidentified as P. cavaleriei in Chinese herbaria, is illustrated and described. The new species closely resembles P. cavaleriei in leaf shape, inflorescence type, and morphology of stamens and capsule, but can be easily distinguished by the leaf veins strongly sunken adaxially, hypanthium pubescent with ca. 1 mm long, spreading glandular hairs, creamy white anthers, and conspicuous ovary crown at anthesis.

Research Progress in Plant Molecular Systematics of Lauraceae.

Simple SummaryLauraceae, as an angiosperm group with high ecological and economic value, has been widely studied. With the development of science and technology, the research of Lauraceae has changed from morphology to molecular systematics. Our paper reviewed the molecular phylogeny of Lauraceae in recent years. From the aspects of gene fragments, chloroplast genome and DNA barcodes, we mainly discussed the establishment of Cinnamomeae in the ‘Core Lauraceae’ and the tribal controversial genera (Actinodaphne, Sassafras, Caryodaphnopsis, Neocinnamomum and Cassytha). We think that the whole genome and inflorescence characteristics are the breakthrough to solve the tribal problem of Lauraceae. Using reliable molecular and morphological evidence to reconstruct the phylogenetic relationship of Lauraceae will provide an important theoretical basis for the rational utilization of Lauraceae resources, the development of potential resources and the protection of rare plants.Lauraceae is a large family of woody plants with high ecological and economic value. The tribal and generic division and phylogenetic relationship of Lauraceae have long been controversial. Based on morphological and molecular evidence, phylogenetic relationships within the Cinnamomeae, Laureae and Perseeae tribes, also called ‘the Core Lauraceae’, have arisen particular attention. In this review, we comprehensively collated the literatures on the phylogeny of Lauraceae published in recent years and summarized progress made in molecular systematic researches employing gene fragments, chloroplast genomes and DNA barcodings analyses. We clarified the phylogenetic relationships and main controversies of ‘the Core Lauraceae’, the systemic position of fuzzy genera (Neocinnamomum, Caryodaphnopsis and Cassytha) and the development of chloroplast genome and DNA barcodes. We further suggested and proposed the whole genome analysis and different inflorescence types would be possible to provide more information for further research on phylogenetic relationships and taxonomy of Lauraceae.

Chroesthes (Acanthaceae) in Peninsular Malaysia, including a new species from Kelantan and a new record from Terengganu.

Chroesthes is a small genus that includes three species from Peninsular Malaysia: Chroesthes faizaltahiriana Siti-Munirah sp. nov., C. lanceolata (T. Anderson) B.Hansen and C. longifolia (Wight) B.Hansen. Chroesthes faizaltahiriana, recently discovered in the State of Kelantan, is described and illustrated. This species is similar to the common species C. longifolia, but is distinguished mainly by its inflorescence type, calyx shape and its flowers being bright orange instead of dark purple internally. Chroesthes lanceolata is a new record for Peninsular Malaysia and has only been collected once. Following the IUCN Red List Categories and Criteria, these three species are assessed (national scale assessment) as Critically Endangered (C. faizaltahiriana and C. lanceolata) and Least Concern (C. longifolia).

Identification of a Locus Controlling Compound Raceme Inflorescence in Mungbean [Vigna radiata (L.) R. Wilczek

Mungbean [Vigna radiata (L.) R. Wilczek] produces a compound raceme inflorescence that branches into secondary inflorescences, which produce flowers. This architecture results in the less-domesticated traits of asynchronous pod maturity and multiple harvest times. This study identified the genetic factors responsible for the compound raceme of mungbean, providing a unique biological opportunity to improve simultaneous flowering. Using a recombinant inbred line (RIL) population derived from VC1973A, an elite cultivar with a compound raceme type, and IT208075, a natural mutant with a simple raceme type, a single locus that determined the inflorescence type was identified based on 1:1 segregation ratio in the F8 generation, and designated Comraceme. Linkage map analysis showed Comraceme was located on chromosome 4 within a marker interval spanning 520 kb and containing 64 genes. RILs carrying heterozygous fragments around Comraceme produced compound racemes, indicating this form was dominant to the simple raceme type. Quantitative trait loci related to plant architecture and inflorescence have been identified in genomic regions of soybean syntenic to Comraceme. In IT208075, 15 genes were present as distinct variants not observed in other landrace varieties or wild mungbean. These genes included Vradi04g00002481, a development-related gene encoding a B3 transcriptional factor. The upstream region of Vradi04g00002481 differed between lines producing the simple and compound types of raceme. Expression of Vradi04g00002481 was significantly lower at the early vegetative stage and higher at the early reproductive stage, in IT208075 than in VC1973A. Vradi04g00002481 was therefore likely to determine inflorescence type in mungbean. Although further study is required to determine the functional mechanism, this finding provides valuable genetic information for understanding the architecture of the compound raceme in mungbean.

Hormonal and carbohydrate control of fruit set in avocado ‘Lamb Hass’. A question of the type of inflorescence?

The avocado tree (Persea americana Mill.) has two types of shoots, indeterminate, which maintain vegetative development from an apical bud, and determinate, which do not have vegetative growth. Indeterminate shoots set fewer fruits than determinate ones, and significantly hasten physiological fruitlet abscission. The competition between vegetative and flower development is accepted as the most reasonable hypothesis to explain the differences. However, our results show that from anthesis until fruit set flowers of indeterminate inflorescences, both those remaining on the tree and those abscised, had a higher sucrose and C6 carbohydrate content than flowers of determinate ones and no differences between them were found for C7 carbohydrates, which disagrees with this hypothesis, and indicates that factors other than carbohydrate content are responsible for fruit set in avocado.At anthesis and fruit set stage, gibberellin and cytokinin concentrations (mainly GA1 and tZ, respectively) were significantly higher in flowers of determinate inflorescences than in those of indeterminate ones, indicating their higher ability to set.We conclude that fruit set is hormonally regulated in avocado, irrespective of vegetative growth. The lower fruit set of the indeterminate inflorescences does not depend on the competition for photosynthates due to the apical vegetative growth, since C6 and C7 carbohydrate availability is enough to ensure fruit set, but on their lower content of GA1 and tZ.

Reproductive Output and Insect Behavior in Hybrids and Apomicts from Limonium ovalifolium and L. binervosum Complexes (Plumbaginaceae) in an Open Cross-Pollination Experiment.

Ex situ plant collections established from seeds of natural populations are key tools for understanding mating systems of intricate taxonomic complexes, as in the Limonium Mill. genus (sea lavenders, Plumbaginaceae). Plants show a polymorphic sexual system associated to flower polymorphisms such as ancillary pollen and stigma and/or heterostyly that prevents self and intramorph mating. The main objectives of this study were to investigate the significance of pollen-stigma dimorphisms and the role of flower visitors in the reproductive output of hybrids arising from sexual diploids of Limonium ovalifolium complex and apomicts tetraploids of L. binervosum complex in an open cross-pollination experiment. Results showed that, similarly to parental plants, hybrids present inflorescence types, self-incompatible flowers, and produced regular pollen grains with the typical exine patterns, with medium to high viability. By contrast, apomicts show floral polymorphisms, inflorescences, and pollen grains of maternal phenotype but with low stainability. Several insects’ species visited the inflorescences of parental plants and both hybrids and apomicts and some of these insects carried A and/or B pollen grains on their bodies, especially Clepsis coriacana (Rebel) and Tapinoma sp. Insects’ floral visits to hybrids and apomicts seem to be independent of pollen fertility and plants’ reproductive modes. Both hybrids and apomicts were able to produce fertile seeds, although the latter showed more seedlings with developmental anomalies than the first plants. The findings demonstrate that there is a weak reproductive barrier between the diploid species of L. ovalifolium complex as they can hybridize and produce fertile hybrids, provided there is pollen transport by pollinator insects. This study supports that apomixis is a strong reproductive barrier between both L. ovalifolium and L. binervosum complexes but did not allow us to exclude reproductive interferences of apomict pollen into sexuals.

Orchidaceae in a fragment of restinga on the north coast of Bahia, Brazil

Abstract Área de Proteção Ambiental das Lagoas e Dunas do Abaeté (APA Abaeté) is an urban fragment of restinga in an environmentally protected area in the municipality of Salvador, Bahia, Brazil. The area is impacted by irregular disposal of solid waste, clandestine removal of sand from dunes, suppression and fragmentation of original vegetation cover and urban growth of neighborhoods. A recent floristic study revealed new records of orchid species for this conservation unit but highlighted strong threats to the orchid flora. In this context, a taxonomic study of Orchidaceae in APA Abaeté was undertaken with the aim of facilitating the recognition of species in the field and supporting the establishment of more effective local conservation actions for orchids, which should include the manual dispersion of seeds and the relocation of individuals. Orchidaceae is the sixth most represented family in APA Abaeté, with 15 genera and 19 species, including Encyclia dichroma and Koellensteinia florida, endemic species of the Atlantic Forest. The most relevant morphological characteristics for the identification of species in the area are: growth type; climbing habit; caulome thickness; shape and consistency of leaf blades; inflorescence type and position; and color and resupination of flowers.

Study of rice genotypes and their use in the process of selection

This research was aimed the use of non-traditional, biochemical marker-based selection methods in synchronization with classical methods in rice selection, rapid adaptation to adverse environmental factors, disease tolerance, lodging and shedding resistance, high yield and technological quality of rice. According to the results of the experiment, 42 varieties in 2018, 28 in 2019 and 39 in 2020 with a total of 109 combinations of 7172 flowers were selected with the participation of varieties and specimens that are resistant to various environmental influences and diseases, high yield, high grain quality. was carried out. The results of the hybridization showed that 118 (or 3.78%) in 2018, 117 (or 5.35%) in 2019, 81 (or 4.35%) in 2020, a total of 316 (or 4.4%) hybrid populations were taken. F1 generation hybrids obtained from the combinations of Chongwang x TShD 15-13 and Chongwang x 227-09, was recommended not to use these combinations in future studies due to the low dominance of “Ruvak” (paniculo is a type of plant inflorescence) length and 1000 grain weight.

Molecular systematics of the tribe Prismatomerideae (Rubiaceae) and its taxonomic consequences, with notes on the importance of the inflorescence morphology for species‐group recognition in Rennellia

AbstractTropical Asia is one of the centers of species diversity of flowering plants, in particular the coffee family (Rubiaceae). Prismatomerideae (the Psychotrieae alliance, subfamily Rubioideae) are a mostly Southeast Asian tribe encompassing four genera of shrubs and small trees (monospecific Gentingia and Motleyia, Prismatomeris with 16 spp., Rennellia with 4–5 spp.). We conducted molecular phylogenetic analyses of this group based on the nuclear and plastid sequence data from six markers and using Bayesian inference. The main goal was to produce a robust phylogeny of the tribe, which was subsequently used to (1) reassess its monophyly and phylogenetic position within the Psychotrieae alliance; (2) rigorously test the monophyly of Prismatomeris and Rennellia; (3) assess the phylogenetic relationships between the genera; and (4) evaluate the phylogenetic value of the inflorescence type currently used for species recognition in Rennellia. Motleyia was not sequenced due to the lack of material, and therefore its affinity with the other genera was assessed based on morphology. The tribe was supported as monophyletic and resolved as sister to the (Gaertnereae (Mitchelleae‐Morindeae)) clade. The monophyly of Prismatomeris sensu Johansson was strongly supported, but we argue for the merging of the monospecific genus Motleyia into Prismatomeris based on their strong morphological similarities coupled with the paraphyly of Prismatomeris with respect to Motleyia. Rennellia was strongly supported as paraphyletic with respect to Gentingia. We propose the transfer of the monospecific genus Gentingia to Rennellia, also consistent with their strong morphological resemblance. Prismatomerideae were resolved in two major sister lineages, the Prismatomeris and Rennellia clades, corresponding to our broadly delimited Prismatomeris and Rennellia. Three well‐supported and morphologically distinct subclades were identified within Rennellia s.l., of which one was represented by Rennellia subsessilis, with sessile and reduced umbel‐like inflorescences bearing two to four flowers. The other two subclades have compound spike‐like (or sub‐raceme‐like) and raceme‐like inflorescences, an important distinction in species‐group recognition. We conclude that inflorescence type shows a strong phylogenetic signal and is, therefore, a reliable feature for recognizing groups of species in Rennellia. Additional taxonomic characters are, however, needed for teasing apart closely related species with the same inflorescence types. Subsequent to our taxonomic revision, the tribe Prismatomerideae comprises two genera: Prismatomeris and Rennellia. One and two new combinations, respectively, are presented, bringing the total number of species in the tribe to 25, of which 17 are in Prismatomeris and 8 in Rennellia. A new species key to Rennellia s.l. is presented.

MtFULc controls inflorescence development by directly repressing MtTFL1 in Medicago truncatula

Flowering plants display a vast diversity of inflorescence architecture, which plays an important role in determining seed yield and fruit production. Unlike the model eudicot Arabidopsis thaliana that has simple inflorescences, most legume plants have compound types of inflorescences. Recent studies in the model legume species Pisum sativum and Medicago truncatula showed that the MADS-box transcription factors VEGETATIVE1/PsFRUITFULc/MtFRUITFULc (VEG1/PsFULc and MtFULc) are essential for the development of compound inflorescences by specifying the secondary inflorescence meristem identity. In this study, we report the isolation and characterization of two new mtfulc alleles by screening the M. truncatula Tnt1 insertion mutant collection. We found that MtFULc specifies M. truncatula secondary inflorescence meristem identity in a dose-dependent manner. Biochemical analysis and chromatin immunoprecipitation (ChIP) assays revealed that MtFULc acts as a transcriptional repressor to directly repress the expression of MtTFL1 through its promoter and 3′ intergenic region. Comprehensive genetic analysis suggest MtFULc coordinates with the primary inflorescence meristem maintainer MtTFL1 and floral meristem regulator MtPIM to control M. truncatula inflorescence development. Our findings help to elucidate the mechanism of MtFULc-mediated regulation of secondary inflorescence meristem identity and provide insights into understanding the genetic regulatory network underlying compound inflorescence development in legumes.

Flower morphology and ontogeny of endemic Crataegus tanacetifolia (Lam.) Pers. (Rosaceae) from Turkey

In this study, flower morphology and ontogeny of Turkish endemic Crataegus tanacetifolia Lam. Pers. (Rosaceae) were studied using stereo, light and scanning electron microscope. C. tanacetifolia has corymb type of inflorescence which bears 5-10 hermaphrodite flowers. The first sign in appearance of the flowers is the differentiation of apical meristem as a roundish bulge. It transforms into the floral meristem which gives rise to floral organ primordia in advanced stages. 20 stamen primordia differentiate as roundish bulge from the sides of floral meristem. Subsequently, the stamen primordia start stretching and differantiating into filaments and anthers respectively. After a short time of stamen initiation, 5 carpel primordia differentiate from the floral meristem. In following stages, the carpel primordia elongate and form an ovary with 5 loculi. During the ovary formation, 5 styles occur on the ovary and then stigmas evolve out of styles tips.

Phylogeny, Diversification Rate, and Divergence Time of Agave sensu lato (Asparagaceae), a Group of Recent Origin in the Process of Diversification.

Agave sensu lato is one of the most diverse and complex genera of Asparagaceae, with more than 250 species. The morphological, ecological, and evolutionary diversity of the group has complicated its taxonomical study. We conducted phylogenetic analyses of DNA sequence data to reconstruct the phylogenetic relationships of the Agave genus. We included 107 species of the Asparagaceae family from which 83 correspond to the Agave sensu lato clade (Agave sensu stricto + Polianthes + Manfreda and Prochnyanthes, which together represent 30% of the genus) and as outgroups the genera Dasylirion, Hesperoyucca, Chlorogalum, Camassia, Hesperaloe, Yucca, Beschorneria, and Furcraea, in order to estimate the age and propose the history of their diversification. Previous studies postulated the relevance of the Miocene in the speciation rates of the agaves, as well as the relevance of the type of inflorescence in its diversification. However, these assertions have not been well supported. The analysis of chloroplast regions resulted in low resolution, which could be the consequence of the few variable sites. On the other hand, the internal transcribed spacer (ITS) implemented in our analysis ensued in higher resolution and better support values. Our phylogenetic analyses recovered five groups; one is the Striatae group, which is the sister group to Agave sensu stricto clade. Within this clade, we found three main groups with high support; these groups are not related with previous morphological proposals. We also analyzed the dates of origin and diversification rates. A Bayesian analysis of macroevolutionary mixtures indicated two significant shifts; the first was identified at 6.18 Ma, where the speciation rate increased to 4.10 species/Mya, this shift occurred during the late Miocene period, characterized by the emergence of arid biomes in North America. The second was identified at a stem age of 2.68 Ma where the speciation rate increased to 6.04 species/Mya. Concerning the ancestral reconstruction state of the inflorescence type in the Agave sensu stricto clade, the spike inflorescence character was predominant in the early-diverging groups, whereas the late-diverging groups present panicle inflorescences as the predominant character and higher speciation rates.

Gender expression in Sedum praealtum A. DC. (Crassulaceae) in Central Veracruz, Mexico

Inflorescence type and design determine the position of reproductive meristems and sequence of flowers opening. I examined the gender expression over two entire flowering seasons in Sedum praealtum A. DC. (Crassulaceae) in Central Veracruz, Mexico. Specifically, I studied the floral longevity, sexual-phase duration, flower opening within an inflorescence and sex ratio in the species. I observed that the 8-days flower initiated in male-phase and then switched to female-phase. An extended time of pollen presentation by gradual anthers dehiscence caused an incomplete protandry in the species. The basal-positioned floral buds reached anthesis sooner than the distal-positioned floral buds, resembling an acropetal flowering sequence. Inflorescences production ceased in the middle of the flowering season, whereas flower opening remained constant over reproductive season of the species. The opening of flowers in successive cohorts linked to changes in the flower sexual-phase phenology caused an initial sex expression toward maleness and a balanced sexual expression from the peak to the end of reproductive season in the population sampled. This study highlights the important influence that variations in onset and duration of sexual-phase of flowers can have on sex expression in flowering plants.