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Position of the landmarks for the three flower types. (a) aconitum type. (B) Consolida type. (C) Delphinium type.
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The variation in the shape of flowers, the reproductive structures of angiosperms, is generally investigated in a qualitative way, or using multivariate statistical analyses of distance data (i.e. traditional morphometrics). In this study, we evaluate the application of geometric morphometric methods to flowers of herbarium specimens, a material th...
Contexts in source publication
Context 1
... characterize the shape of these floral structures, we used a set of nine landmarks (three for the dorsal sepal and six for the dorsal petal; Figure 3 and Supplementary Table 2) and seven series of 20-25 semilandmarks to capture the homologous curved outlines of the sepal and the petal between the landmarks (Gunz and Mitteroecker 2013). The coordinates of these landmarks and semilandmarks were manually recorded from the 60 photographs using the software tpsDig2 (Rohlf 2015). ...
Context 2
... characterize the shape of these floral structures, we used a set of nine landmarks (three for the dorsal sepal and six for the dorsal petal; Figure 3 and Supplementary Table 2) and seven series of 20-25 semilandmarks to capture the homologous curved outlines of the sepal and the petal between the landmarks (Gunz and Mitteroecker 2013). The coordinates of these landmarks and semilandmarks were manually recorded from the 60 photographs using the software tpsDig2 (Rohlf 2015). We decided not to consider the stalk of the petal in the analyses, as this structure is very slender in Aconitum, making it difficult to place the semilandmarks between landmarks 4 and 5, and 4 and ...
Citations
... Kuhl and Giardina 1982), allowing the analysis of structures shapes and their variation. It uses non-quantitative variables through coordinates of landmarks, which collect geometric information on their relative position (Chen et al. 2018). It enables the visualization of multivariate analyses results as a configuration of landmarks from the original spatial configuration of the organism (Adams et al. 2004). ...
... GM are powerful analytic tools in constant development that offer a new way of studying species evolution (Savriama 2018), systematics (Liu et al. 2018;Menini Neto et al. 2019), and even phylogeography (Terral et al. 2004(Terral et al. , 2012 or ecology (García-Jain et al. 2022) and archaeophenomics (Evin et al. 2022) by collecting and comparing the morphology of organisms. GM studies in plants have been implemented with ancient plant organs (Terral et al. 2004(Terral et al. , 2012, functional traits ( Van der Niet et al. 2010;Neustupa and Nemcova 2022), and floral symmetry (Chen et al. 2018;Savriama 2018). ...
... Our approach using GM has assessed fruit shape variation in a non-qualitative way, as it is commonly studied on traditional morphometrics (Chen et al. 2018). Some examples of systematic and taxonomic implications derived from GM have been previously done in Liu et al. (2018) with Chinese oaks leaves, Terral et al. (2012) with the seeds of Phoenix genera species, or Van der Niet et al. (2010) assessing flower shape variation. ...
Geometric morphometrics (GM) is a powerful analytical tool that enables complete quantification of shapes. Its use in Botany has a great potential for complementing plant evolutionary and ecological studies. Taxonomic delimitation in Carex has been complicated due to reduction of characters and frequent homoplasy. This problem is more marked in cases where the species exhibit dwarfism. South America is the continent with the least understood Carex flora. The systematic relationships of some bizarre looking groups were not unraveled until molecular phylogenetic studies resolved their relationships. In particular, there are two species only known from their type material whose affinities remain uncertain: Carex herteri and C. hypsipedos. These two taxa are acaulescent plants that respectively grow in the Uruguayan pampa and Peruvian high-altitude meadows. Recently, both species were ascribed to the Carex phalaroides group (subgen. Psyllophorae, sect. Junciformes) due to superficial morphological similarities, such as the androgynous peduncled spikes. However, their character combination is also coincident for its circumscription to sect. Abditispicae species. Nevertheless, in the absence of confirmation from molecular analyses, their placement must be considered preliminary until additional data can be provided. In this work we employ for the first time geometric morphometrics (GM) tools to assess the systematic affinities of two taxonomically problematic sedge species based on fruit shape. We compared utricle morphology of C. herteri and C. hypsipedos with that of C. phalaroides group and species in sect. Abditispicae. To this end we used GM and traditional morphometric approaches. Utricle shape variation along with other morphological features support the exclusion of these two species from the C. phalaroides gr. and, at the same time, show clear affinities of C. herteri to sect. Abditispicae. Carex hypsipedos remains as an incertae sedis species. Our work shows the potential utility of GM for the exploration of systematic affinities in sedges and in other graminoids.
... /2023 4 are spurred and nectariferous. These petals are nested within the spurred sepal (Jabbour and 108 Renner, 2012b), and their morphology ( Figure 2) and development have been extensively 109 studied (Jabbour et al., 2009;Chartier et al., 2016;Chen et al., 2018;Jabbour et al., 2021). It 110 is a case of synorganization, that is to say the intimate structural connection of two or more 111 neighbouring floral organs forming a functional system (i.e., a hyperorgan) (Specht and 112 Bartlett, 2009;Jabbour et al., 2021). ...
Floral spurs are invaginations borne by perianth organs (petals and/or sepals) that have evolved repeatedly in various angiosperm clades. They typically store nectar and can limit the access of pollinators to this reward, resulting in pollination specialization that can lead to speciation in both pollinator and plant lineages.
Despite the ecological and evolutionary importance of nectar spurs, the cellular mechanisms involved during spur development have only been described in detail in a handful of species, primarily with respect to epidermal cells. These studies show that the mechanisms involved are taxon-specific.
Using confocal microscopy and automated 3D image analysis, we studied spur morphogenesis in Staphisagria picta (Ranunculaceae) and showed that the process is marked by an early phase of dominant cell proliferation, followed by a phase of anisotropic (directional) cell expansion.
The comparison with Aquilegia , another taxon of Ranunculaceae with spurred petals, revealed that the convergence in form between the spurs of both taxa is obtained by partially similar developmental processes. The analytical pipeline designed here is an efficient method to visualize in 3D each cell of a developing organ, paving the way for future comparative studies of organ morphogenesis in multicellular eukaryotes.
Highlight
A new method of 3D analysis of plant tissues at the cellular level revealed that spur morphogenesis in Staphisagria picta is marked by an early phase of dominant cell proliferation, followed by a phase of anisotropic cell expansion. Floral spur development is analysed for the first time quantitatively, taking into account all tissues composing the organ, namely epidermis and parenchyma.
... Однако до последнего времени отсутствуют работы по геометрической морфометрии представителей рода Delphinium. Исключение составляет только исследование, посвящённое формообразованию цветочных структур у Delphinieae (Chen et al., 2018). Кроме того, следует указать работы по исследованию формы листовых пластинок у комплекса Ranunculus auricomus L., относящегося, как и род Delphinium, к семейству Ranunculaceae (Hodač et al., 2018;Karbstein et al., 2020). ...
The leaf blade’s shape of 665 samples of 18 taxa from the genus Delphinium was analyzed using geometric morphometrics method. Within the subgenus Delphinastrum, D. elatum and, to a lesser extent, D. uralense were relatively well separated by canonical analysis, while D. litwinowii, D. pubiflorum, D. duhmbergii, and D. subcuneatumwere not actually separated. Within the subgenus Oligophyllon, D. caucasicum was well separated by this method. The scatter clouds of D. freynii + D. puniceum + D. sergii on the one hand, and D. fedorovii + D. gelmetzicum on the other hand, also separated. D. arcuatum, D. bracteosum, D. crispulum, D. flexuosum, and D. mariae did not separate from each other. The nature of such separation of species groups observed in the space of canonical variables and their relative proximity to each other can be associated with the habitat similarity of their populations driven by ecological or geographical conditions, as well as the influence of hybridization processes in the zone of secondary contact of species. The differences in leaf blade’s shape are mainly related to the width of the segments, the lengths of the central segment of the middle lobe and the undissected part of the leaf blade, the degree of its dissection, the shape of the base and the distance between the lower lobes. Based on the results of DNA sequencing of the intergenic transcribed spacer ITS2, the taxonomic independence of D. puniceum, D. macropogon, D. mariae, D. samurense, and D. pubiflorum is beyond any doubt. The synonymy of D. freynii and D. sergii is supported, with the priority name of D. schmalhausenii. D. cuneatum, D. subcuneatum, D. duhmbergii, and D. litwinowii should be considered as synonyms with the priority name of D. cuneatum. The taxonomic status of D. dictyocarpum, D. elatum, and D. uralense needs further clarification. This is probably related to their easy hybridization with D. cuneatum in sympatric populations within the overlapping areas. Delphinium arcuatum, D. bracteosum, D. caucasicum, D. crispulum, D. elisabethae, D. fedorovii, D. flexuosum, D. gelmetzicum, and D. speciosum are poorly separated, which can also be associated with hybridization processes. They need to be studied in more detail.
... Although this tool has a long tradition of use in anthropology, zoology, and paleobiology, its application is still in its infancy in the study of flower shapes, in part due to the technical difficulty of obtaining accurate 3D models of flowers, which are needed to accurately quantify the 3D structure of a flower (van der Niet et al., 2010). Accordingly, most studies employing geometric morphometric approaches in flowers have used a 2D approach based on herbarium specimens and photos and only focused on subsets of floral organs (i.e., corolla, style; Chen et al., 2018;Rozov et al., 2018;Kriebel et al., 2020), impeding our ability to understand the joint functioning of floral organs. Recent methodological advances in the acquisition of 3D flower models, such as the development of protocols specifically tailored for preparing flowers for CT scanning (Staedler et al., 2013(Staedler et al., , 2018, (affordable) photogrammetry (Leménager et al., 2022), or virtual 3D modeling (van de Kerke et al., 2020), hold great potential for advancing the field ( Figure 5). ...
Premise:
Floral shape (relative arrangement and position of floral organs) is critical in mediating fit with pollinators and maximizing conspecific pollen transfer particularly in functionally specialized systems. To date, however, few studies have attempted to quantify flowers as the inherently three-dimensional (3D) structures they are and determine the effect of intraspecific shape variation on pollen transfer. We here addressed this research gap using a functionally specialized system, buzz pollination, in which bees extract pollen through vibrations, as a model. Our study species, Meriania hernandoi (Melastomataceae), undergoes a floral shape change from pseudocampanulate corollas with more actinomorphically arranged stamens (first day) to open corollas with a more zygomorphic androecium (second day) over anthesis, providing a natural experiment to test how variation in floral shape affects pollination performance.
Methods:
In one population of M. hernandoi, we bagged 51 pre-anthetic flowers and exposed half of them to bee pollinators when they were in either stage of their shape transition. We then collected flowers, obtained 3D flower models through x-ray computed tomography for 3D geometric morphometric analyses, and counted the pollen grains remaining per stamen (male pollination performance) and stigmatic pollen loads (female pollination performance).
Results:
Male pollination performance was significantly higher in open flowers with zygomorphic androecia than in pseudo-campanulate flowers. Female pollination performance did not differ among floral shapes.
Conclusions:
These results suggest that there is an "optimal" shape for male pollination performance, while the movement of bees around the flower when buzzing the spread-out stamens results in sufficient pollen deposition regardless of floral shape.
... Collection of distribution data. -It is sometimes impossible to confidently study the morphology of fragile floral macrostructures in herbarium specimens, because spatial structures usually get damaged during pressing (Chen & al., 2018). Given the fragility of these morphological characters in Salvia flowers, we restricted our screening for occurrence records to public image repositories of plants with a geographic tag of the location where the picture was taken. ...
Salvia is the most species-rich genus of the family Lamiaceae, currently numbering almost 1000 species. The diagnostic feature of the genus is the unique staminal lever mechanism that allows for specific pollination modes. We encountered an unusual Salvia form in the field, in SE Romania, which resembles S. austriaca but features a radically different lever mechanism. This form proved to be geographically widespread on the Pontic steppe, never occurring in sympatry with S. austriaca. We used an integrative approach, employing morphometric and phylogenomic (RADseq) analyses, to study this unusual form. The taxon's floral morphology proved to be consistently and subtly different from that of S. austriaca, and similarly, Bayesian species delimitation using genome-wide SNP data indicated species-level differences. Our results provide compelling evidence that points toward the discovery of an unrecognized species. This species has been overlooked for centuries, misidentified as S. austriaca, a closely related taxon. The new species differs from S. austriaca in key features of floral structure, habitat preference, and distribution. The potential range of this cryptic species, its pollination biology, ecology, and phylogeography are discussed.
... Synorganized floral parts have been described in a wide range of angiosperm lineages (Endress 1990(Endress , 2010a. In Ranunculales, the earliest-diverging order of eudicots (APG IV 2016), synorganization was briefly reported in the flowers of the tribe Delphinieae, in which the nectar spurs of the dorsal petals are nested within the hollow dorsal sepal (Chartier et al. 2016;Chen et al. 2018;Jabbour et al. 2020b). The phylogenetic position of Delphinieae within Ranunculaceae and floral morphological evolution in the family were both clarified recently (Zhai et al. 2019;Carrive et al. 2020). ...
Premise of the research. Floral synorganization is a structural feature of many speciose angiosperm taxa, and is considered as a morphological innovation paving the way for evolutionary diversification. Staphisagria is sister to the remaining Delphinieae, the only lineage of Ranunculaceae characterized by zygomorphic flowers. We aim at providing a description of floral organogenesis and morphogenesis in both Staphisagria species, presenting the disparity of Delphinieae hyperorgan in a phylogenetic framework, and proposing a scenario of likely developmental pathways underlying the different types of hyperorgans in Delphinieae.
Methodology. We carried out morphological, anatomical, and developmental studies on flowers of Staphisagria macrosperma and S. picta. Pivotal results. Synorganization is complex in Staphisagria and Delphinieae as a whole, and involves flower dorsoventralization, nesting of spurs, postgenital fusion of petals, and the formation of a shared cavity. From a choripetalous ancestor, late and partial postgenital fusion among dorsal petals evolved once or twice in the tribe.
Conclusions. Delphinieae flower includes nested spurs and nested floral parlors. These key innovations, unique in angiosperms, probably led to the diversification of this species-rich tribe in the Northern Hemisphere. The length of the inner (nectariferous) spurs and the nested floral parlors determine the range of pollinators able to collect nectar. These traits could be used to revise the circumscription of taxonomic groups within the tribe, and should be taken into account when examining the possible coevolution between Delphinieae flowers and their pollinators. Integrating this new knowledge about the hyperorgan will be essential for future research in taxonomy, evo-devo and pollination ecology in Delphinieae.
... Dentant, Lavergne, and Malécot (2018) conducted a thorough study of the taxonomy of rockjasmines (genus Androsace, Primulaceae), while Henning et al. (2018) introduce a workflow currently implemented on the EDIT Platform for Cybertaxonomy, which improves use and sustainable handling of specimen data. In addition, we also present a short review about the techniques used to prepare herbarium specimens for morphological and anatomical studies (Espinosa and Pinedo Castro 2018), and, to our knowledge, the first study investigating the morphological diversity of herbarium flowers using geometric morphometrics (Chen et al. 2018). ...
Premise:
Pollinators are thought to exert selective pressures on plants, mediating the evolution of convergent floral shape often recognized as pollination syndromes. However, little is known about the accuracy of using petal shape for inferring convergence in pollination mode without a priori pollination information. Here we studied the genus Erythrina L. as a test case to assess whether ornithophyllous pollination modes (hummingbirds, passerines, sunbirds, or mixed pollination) can be inferred based on the evolutionary analysis of petal shape.
Methods:
We characterized the two-dimensional dissected shape of standard, keel, and wing petals from 106 Erythrina species using geometric morphometrics and reconstructed a phylogenetic tree of 83 Erythrina species based on plastid trnL-F and nuclear ribosomal ITS sequences. We then used two phylogenetic comparative methods based on Ornstein-Uhlenbeck models, SURFACE and l1OU, to infer distinct morphological groups using petal shape and identify instances of convergent evolution. The effectiveness of these methods was evaluated by comparing the groups inferred to known pollinators.
Results:
We found significant petal shape differences between hummingbird- and passerine-pollinated Erythrina species. Our analyses also revealed that petal combinations generally provided better inferences of pollinator types than individual petals and that the method and optimization criterion can affect the results.
Conclusions:
We show that model-based approaches using petal shape can detect convergent evolution of floral shape and relatively accurately infer pollination modes in Erythrina. The inference power of the keel petals argues for a deeper investigation of their role in the pollination biology of Erythrina and other bird-pollinated legumes.
As many as 963 herbarium sheets featuring 76 aquatic plant taxa from the ZA collection were digitised and published online through the Virtual Herbarium. Aquatic plants have been collected over a period of 176 years, with three peaks (second decade of the 20th century, in the 1940s and 1950s, and in the current decade). Most of the specimens were collected in Croatia and a smaller number in neighbouring and geographically close countries. The importance of the collection is expressed through the specimens of many rare and threatened species, because it represents the only evidence of their presence in Croatia (the regionally extinct Caldessia parnassifolia, as well as Luronium natans, Callitriche platycarpa, C. truncata, C. hermaphroditica, Potamogeton alpinus, P. compressus, P. polygonifolius, Nuphar × spenneriana and Sparganium minimum). The collection in ZA is a valuable source of data about the historical and recent distribution of aquatic plants that constitute a foundation for the estimation of distribution changes, threat assessment and conservation policies.
