Variation In Leaf Morphology Research Articles

Exploring the acclimation to depth of Posidonia oceanica comparing the morphological variation to the histo-anatomical characteristics of the leaves

Posidonia oceanica is a marine plant that plays an important ecological role in marine ecosystems. Understanding the eco-physiology of this plant is fundamental for planning conservation and restoration actions covering this species and its habitat. The aim of this study was to explore the acclimation of P. oceanica to depth by examining the leaf morphological variation in a depth gradient. We measured leaf length, width and thickness, as well as the distance of fifth and sixth ribs from the margin and the central rib at different depths, comparing leaves morphology and histo-anatomy. Leaf length was the only morphological character clearly related to depth, whereas the overall morphological variation seems to be due to a change in the histo-anatomical characters. Depth-related characters showed a different variation pattern from that of not depth-related ones. Our results do not fit the model used to explain the seagrass responses to light variation; most morphological leaf traits are not directly linked to the acclimation of this species to depth. Finally, we hypothesise that the variation pattern of not depth-dependent characters is an expression of P. oceanica meadow genetic structure along the depth gradient.

Variations of leaf morphology, photosynthetic traits and water-use efficiency in Western-Mediterranean tomato landraces

Modern tomato (Solanum lycopersicum L.) breeding has mainly focused on increasing productivity under unlimited watering. In contrast, some Mediterranean accessions have been traditionally cultivated under water shortage and selected on the basis of their water-use efficiency (WUE). Ramellet and Penjar landraces were planted with other traditional, old and modern inbreeds, under full irrigation. In order to found differences between the tomato accessions, gas-exchange and leaf morphology measurements were performed. Despite high variability, Ramellet and Penjar presented clear differences compared to modern cultivars, mostly related to leaf morphology and photosynthetic traits, while no differences were found in WUE. Results highlighted that better leaf CO2 conductance might be a main factor determining the improvement of net CO2 assimilation and WUE.

Species-specific alleles at a β-tubulin gene show significant associations with leaf morphological variation within Quercus petraea and Q. robur populations

Quercus petraea and Q. robur are largely sympatric oak species in western and central Europe and known for their intensive genetic exchange which has made the discovery of species-diagnostic markers a huge challenge. Various natural white oak populations (Q. petraea/Q. robur including mixed stands) were investigated for their variability and differentiation patterns at a β-tubulin gene (qutub8) in a European-wide survey. This gene was chosen as a possible candidate among loci subjected to selection and maintaining integrity between species. Two frequent alleles depicted as indels within qutub8’s first intron showed remarkably high interspecific genetic differentiation, with Weir and Cockerham’s theta per allele values ranging from 0.17 to 0.30 for one allele and from 0.04 to 0.19 for the other allele in such mixed oak stands where the multi-allelic qutub8 locus showed significant interspecific F ST . For three mixed stands, qutub8’s F ST significantly departed from the expected neutral differentiation patterns (F ST ranging from 0.063 to 0.080 for this multi-allelic marker) and thus could be influenced by selection. Significant associations were found between genotypic variation and leaf dimensions as well as leaf structure patterns, after having accounted for species and stand effects. Qutub8 represents a locus that exhibits significant species differentiation and is linked to morphological discriminant traits. Consequently, qutub8 likely contributes to species divergence within the European white oak complex.

Association of genetic and phenotypic variability with geography and climate in three southern California oaks

Geography and climate shape the distribution of organisms, their genotypes, and their phenotypes. To understand historical and future evolutionary and ecological responses to climate, we compared the association of geography and climate of three oak species (Quercus engelmannii, Quercus berberidifolia, and Quercus cornelius-mulleri) in an environmentally heterogeneous region of southern California at three organizational levels: regional species distributions, genetic variation, and phenotypic variation. We identified climatic variables influencing regional distribution patterns using species distribution models (SDMs), and then tested whether those individual variables are important in shaping genetic (microsatellite) and phenotypic (leaf morphology) variation. We estimated the relative contributions of geography and climate using multivariate redundancy analyses (RDA) with variance partitioning. The modeled distribution of each species was influenced by climate differently. Our analysis of genetic variation using RDA identified small but significant associations between genetic variation with climate and geography in Q. engelmannii and Q. cornelius-mulleri, but not in Q. berberidifolia, and climate explained more of the variation. Our analysis of phenotypic variation in Q. engelmannii indicated that climate had more impact than geography, but not in Q. berberidifolia. Throughout our analyses, we did not find a consistent pattern in effects of individual climatic variables. Our comparative analysis illustrates that climate influences tree response at all organizational levels, but the important climate factors vary depending on the level and on the species. Because of these species-specific and level-specific responses, today's sympatric species are unlikely to have similar distributions in the future.

Recognition and differentiation of species in the Passiflora sidifolia complex

The variation in leaf morphology observed in Passifloraceae is one of the most extreme cases in the Angiosperms, allowing some species within this family to be distinguished by their leaves. Nevertheless, other species in this family are difficult to recognize based solely on leaf morphology, or by floral and molecular characteristics. Aiming to verify the similarities and differences between the Passiflora species Passiflora actinia Hook., Passiflora elegans Mast., Passiflora sidifolia M.Roem., and Passiflora watsoniana Mast., detailed analyses were conducted regarding the morphological traits of the leaf blade, specifically shape and venation, and the flower. The data were composed of continuous and qualitative values, using the Gower coefficient. A principal coordinates analysis (PCoA) and cluster analysis were performed. Features that have not previously been used for the Passifloraceae, such as leaf venation, were important for the distinction of P. watsoniana from the other species. The analyses including only the species P. actinia, P. sidifolia, and P. elegans showed a clear differentiation between them. Despite the wide variability observed in P. elegans, the analysis revealed that the different populations from different regions had more similarities with each other than with any other species.

Behavior of Leaf Meristems and Their Modification.

A major source of diversity in flowering plant form is the extensive variability of leaf shape and size. Leaf formation is initiated by recruitment of a handful of cells flanking the shoot apical meristem (SAM) to develop into a complex three-dimensional structure. Leaf organogenesis depends on activities of several distinct meristems that are established and spatiotemporally differentiated after the initiation of leaf primordia. Here, we review recent findings in the gene regulatory networks that orchestrate leaf meristem activities in a model plant Arabidopsis thaliana. We then discuss recent key studies investigating the natural variation in leaf morphology to understand how the gene regulatory networks modulate leaf meristems to yield a substantial diversity of leaf forms during the course of evolution.

Phylogeny and biogeography of the American live oaks (Quercus subsection Virentes): a genomic and population genetics approach.

The nature and timing of evolution of niche differentiation among closely related species remains an important question in ecology and evolution. The American live oak clade, Virentes, which spans the unglaciated temperate and tropical regions of North America and Mesoamerica, provides an instructive system in which to examine speciation and niche evolution. We generated a fossil-calibrated phylogeny of Virentes using RADseq data to estimate divergence times and used nuclear microsatellites, chloroplast sequences and an intron region of nitrate reductase (NIA-i3) to examine genetic diversity within species, rates of gene flow among species and ancestral population size of disjunct sister species. Transitions in functional and morphological traits associated with ecological and climatic niche axes were examined across the phylogeny. We found the Virentes to be monophyletic with three subclades, including a southwest clade, a southeastern US clade and a Central American/Cuban clade. Despite high leaf morphological variation within species and transpecific chloroplast haplotypes, RADseq and nuclear SSR data showed genetic coherence of species. We estimated a crown date for Virentes of 11Ma and implicated the formation of the Sea of Cortés in a speciation event ~5Ma. Tree height at maturity, associated with fire tolerance, differs among the sympatric species, while freezing tolerance appears to have diverged repeatedly across the tropical-temperate divide. Sympatric species thus show evidence of ecological niche differentiation but share climatic niches, while allopatric and parapatric species conserve ecological niches, but diverge in climatic niches. The mode of speciation and/or degree of co-occurrence may thus influence which niche axis plants diverge along.

Genetical genomics of Populus leaf shape variation.

BackgroundLeaf morphology varies extensively among plant species and is under strong genetic control. Mutagenic screens in model systems have identified genes and established molecular mechanisms regulating leaf initiation, development, and shape. However, it is not known whether this diversity across plant species is related to naturally occurring variation at these genes. Quantitative trait locus (QTL) analysis has revealed a polygenic control for leaf shape variation in different species suggesting that loci discovered by mutagenesis may only explain part of the naturally occurring variation in leaf shape. Here we undertook a genetical genomics study in a poplar intersectional pseudo-backcross pedigree to identify genetic factors controlling leaf shape. The approach combined QTL discovery in a genetic linkage map anchored to the Populus trichocarpa reference genome sequence and transcriptome analysis.ResultsA major QTL for leaf lamina width and length:width ratio was identified in multiple experiments that confirmed its stability. A transcriptome analysis of expanding leaf tissue contrasted gene expression between individuals with alternative QTL alleles, and identified an ADP-ribosylation factor (ARF) GTPase (PtARF1) as a candidate gene for regulating leaf morphology in this pedigree. ARF GTPases are critical elements in the vesicular trafficking machinery. Disruption of the vesicular trafficking function of ARF by the pharmacological agent Brefeldin A (BFA) altered leaf lateral growth in the narrow-leaf P. trichocarpa suggesting a molecular mechanism of leaf shape determination. Inhibition of the vesicular trafficking processes by BFA interferes with cycling of PIN proteins and causes their accumulation in intercellular compartments abolishing polar localization and disrupting normal auxin flux with potential effects on leaf expansion.ConclusionsIn other model systems, ARF proteins have been shown to control the localization of auxin efflux carriers, which function to establish auxin gradients and apical-basal cell polarity in developing plant organs. Our results support a model where PtARF1 transcript abundance changes the dynamics of endocytosis-mediated PIN localization in leaf cells, thus affecting lateral auxin flux and subsequently lamina leaf expansion. This suggests that evolution of differential cellular polarity plays a significant role in leaf morphological variation observed in subgenera of genus Populus.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0557-7) contains supplementary material, which is available to authorized users.

<span lang="EN-GB">Taxonomy, typification and karyology of Crepis lacera (Asteraceae)</span>

Crepis lacera is a diploid species (2n = 8), mostly occurring in Italy, with a disjunct population in Albania. The names C. lacera, C. latialis and C. lacera f. titani are here lectotypified, and their taxonomic value is discussed. For the latter name, based on morphological, biogeographical and karyological results, we propose here the subspecific rank (C. lacera subsp. titani stat. nov.). In addition, basal leaf morphology variation, the main distinguishing feature between the two subspecies, is discussed in the light of paedomorphosis, and a distribution map for both subspecies is presented.

Leaf Morphology Variation of Populus nigra L. in Natural Populations along the Rivers in Croatia and Bosnia and Herzegovina

Background and Purpose: The aim was to determine the morphological differences between the hairy type of European black poplar (Populus nigra subsp. caudina) and the typical type from the riparian forests populations as well as between the river systems. Hairy black poplar spreads in a mosaic pattern across the Submediterranean climatic type along the River Neretva and the typical European black poplar is growing on alluvial soils along large rivers in the territory of Croatia and Bosnia and Herzegovina. Material and Methods: Samples for leaf morphometric analysis were collected in 17 natural populations of European black poplar along six rivers in Croatia and Bosnia and Herzegovina. Results: Discriminant analyses have determined that in the differentiation of population groups largely contribute some characters such as the distance between the leaf widest part and the leaf base (DBW) and the petiole length (PL). The differences between populations and analysed groups, as well as the differences between populations belonging to a particular river system, were confirmed for all studied characteristics. Conclusions: Significant differences have been determined between the typical and the hairy type of European black poplar in the studied morphological traits and these dissimilarities are in accordance with the climatic differences in respective habitats of continental riparian forests and the Submediterranean type of climate. Populations sampled in the lower course of the River Neretva, which correspond to the hairy type of the European black poplar, have smaller leaves and a greater angle between the first lower lateral vein and the midrib.

C:N:P stoichiometry and leaf traits of halophytes in an arid saline environment, northwest China.

Salinization is an important and increasingly prevalent issue which has broad and profound effects on plant survival and distribution pattern. To understand the patterns and potential drivers of leaf traits in saline environments, we determined the soil properties, leaf morphological traits (specific leaf area, SLA, and leaf dry matter content, LDMC), leaf chemical traits (leaf carbon, C, nitrogen, N, and phosphorus, P, stoichiometry) based on 142 observations collected from 23 sites in an arid saline environment, which is a vulnerable ecosystem in northwest China. We also explored the relationships among leaf traits, the responses of leaf traits, and plant functional groups (herb, woody, and succulent woody) to various saline environments. The arid desert halophytes were characterized by lower leaf C and SLA levels, higher N, but stable P and N:P. The leaf morphological traits were correlated significantly with the C, N, and P contents across all observations, but they differed within each functional group. Succulent woody plants had the lowest leaf C and highest leaf N levels among the three functional groups. The growth of halophytes might be more limited by N rather than P in the study area. GLM analysis demonstrated that the soil available nutrients and plant functional groups, but not salinity, were potential drivers of leaf C:N:P stoichiometry in halophytes, whereas species differences accounted for the largest contributions to leaf morphological variations. Our study provides baseline information to facilitate the management and restoration of arid saline desert ecosystem.

Molecular Phylogeny of <I>Chuquiraga</I> (Asteraceae-Barnadesioideae): Infrageneric Classification and Generic Affinities

Abstract— Chuquiraga is a genus of evergreen shrubs endemic to the arid and semiarid regions of the Andes and southern South America. The genus has been classified into two sections based on its variation in leaf morphology: Chuquiraga and Acanthophylla. Within section Chuquiraga, two series, Chuquiraga and Parviflorae, have been recognized based on variation in size of flower heads. The objectives of this study were to test this classification and to assess the monophyly of Chuquiraga and its intergeneric relationships with the closely related genera Doniophyton and Duseniella. The phylogenetic relationships of 24 of the 27 species and/or subspecies of Chuquiraga (19 of its 22 recognized species), plus 14 species representing seven of the remaining eight genera of Barnadesioideae, and two species of non-barnadesioid Asteraceae were inferred using sequence data from the chloroplast DNA psbA-trnH, rps16-trnK, trnL-rpl32, and/or nuclear ribosomal DNA ITS regions. The plastid and nuclear data sets were analy...

Revision of Pycnandra subgenus Leptostylis and description of subgenus Wagapensia (Sapotaceae), a genus endemic to New Caledonia

The genus Pycnandra Benth. (Sapotaceae, Chrysophylloideae) is endemic to New Caledonia with 66 known species and is subdivided in six subgenera. We have earlier revised four of these subgenera and here continue with P. subgenus Leptostylis and describe P. subgenus Wagapensia. Subgenus Leptostylis is distinguished mainly by its opposite leaves and four sepals, and includes eight species, of which two are described as new (P. amplexicaulis and P. sclerophylla). Two species, P. longiflora and P. micrantha, are assumed extinct because extensive fieldwork has not been able to relocate the plants. Variation in leaf morphology was observed in Leptostylis gatopensis, which is by consequence considered as synonym of Pycnandra filipes. Two additional taxa belong to this subgenus, but cannot presently be described because sufficient fertile material is unavailable. Subgenus Wagapensia is monotypic and readily distinguished on the basis of its subverticillate leaves and leafy shoots usually borne beneath apical clusters of leaves, a character common in Sapotaceae but unique in Pycnandra. The members of P. subgenus Leptostylis occur mainly in maquis vegetation or sclerophyllous forests on ultramafic soil, but three taxa are confined to calcareous areas. Mining activities in New Caledonian ultramafic areas are extensive and because some of these species are naturally rare, IUCN Red List assessments are provided to all species. Pycnandra grandifolia and P. wagapensis are assigned the IUCN status Vulnerable, P. amplexicaulis and P. sclerophylla are considered Endangered, P. filipes subspecies multiflora and P. goroensis are considered to be Critically Endangered, whereas P. micrantha and P. longiflora appear to be extinct.

국내 자생 꾸지뽕나무 잎과 열매의 형태적 특성에 관한 연구

꾸지뽕나무의 수요 증가에 따라 자생지 파괴가 심각한 반면 꾸지뽕나무에 대한 연구는 미비하기 때문에 자생지 복원과 새로운 농가 소득원으로 이용하기 위하여 국내에 자생하는 꾸지뽕나무 16개 집단을 대상으로 엽과 열매의 형태적 특성을 분석한 결과는 다음과 같다. 조사된 꾸지뽕나무 집단에서 엽의 형태적 특성에 대한 유집분석 결과 4개의 그룹으로 구분되었다. 열매의 형태적 특성을 분석하기 위해 꾸지뽕나무 15개 집단의 열매길이, 폭, 무게 등 3가지 형질을 분산 분석한 결과, 유의확률이 p=0.05로 각각의 형질에 따라 집단 간에 차이가 있는 것으로 나타났으며 열매의 3가지 형질별 특성을 이용하여 군집분석을 실시한 결과 세 집단으로 구분되었다. 본 연구결과에 따르면 꾸지뽕나무 엽과 열매의 형태학적 특징은 각 집단 간 차이가 있었으며, 엽의 형태적 특징과 열매의 특징이 일치하지는 않았다. This study was conducted to classify the variation in leaf and fruit morphology among natural grown 16 Cudrania tricuspidata stands. As results of the analysis in C. tricuspidata stands total 134 Species were found and as results of the analysis in leaf morphology, it was grouped as Group IV. By the analysis of variance in length, width, and weight of fruits were differed in 15 C. tricuspidata stands. The length, width, and weight of fruits were higher in Jinan and Sunchang, than Gochang, Gimje, and Goheung. By the cluster analysis of 3 fruit morphology were classified as 3 Groups. According to the results of this study C. tricuspidata leaves and fruit morphological characteristics for each group were compared by analysis there were differences between the morphological characteristics and the characteristics of the fruit did not match.

Disturbances as Hot Spots of Ecotypic Variation: A Case Study with Dryas octopetala

Ecotypic specialization among populations within plant species can result in adaptational lag when the climate changes directionally. However, disturbances, whether caused by direct effects of human activities or indirect effects such as climate change, may represent zones within which natural selection is relaxed. We compared the genetically based variation in leaf morphology in Dryas octopetala within three natural populations arrayed along a snowbank gradient, to that found in a recently colonized gravel pad less than 100 m away (1600 total leaf lengths measured; 4 sites × 10 transects/site × 4 plants/transect × 10 leaves/plant). Elevated among-clone leaf length variation within the disturbed site supported the idea that disturbances may represent “hotspots” of evolutionarily significant genetic variation. In the Arctic, where colonization of disturbances is primarily by native species, adaptive evolution may be more rapid than previously thought due to relaxation of selection and subsequent mixing of previously isolated gene pools in such areas.

Diversity in leaf morphology and physiological characteristics among mango (Mangifera indica) cultivars popular in different agro-climatic regions of India

The present study was aimed to characterize eight different mango cultivars, viz., ‘Alphonso’, ‘Borsha’, ‘Himsagar’, ‘Fazli’, ‘Langra’, ‘Dashehari’, ‘Totapuri’ and ‘Neelum’ popularly grown in different agro-climatic regions in India. Significant differences in gas exchange and leaf morphological characters were observed among cultivars. Higher photosynthesis rate (PN) was recorded in ‘Borsha’, ‘Himsagar’, ‘Langra’ and ‘Neelum’. Across the cultivars PN and CE (carboxylation capacity) were highest in ‘Neelum’ followed by ‘Borsha’. ‘Langra recorded highest WUE and WUEi. The SLA and SLW were maximum in ‘Totapuri’ and ‘Dashehari’ respectively. Maximum epicuticular wax content (ECW) was observed in ‘Totapuri’. The content of Chl a, Chl b, total chlorophyll and carotenoids was highest in ‘Alphonso’. Adaxial and abaxial stomatal numbers were highest in ‘Totapuri’ and ‘Langra’, respectively. The variations in leaf morphology, gas exchange and related traits may be linked to genotypic variation suitable for different agro-climatic regions in India.

Somatic embryogenesis, tetraploidy, and variant leaf morphology in transgenic diploid strawberry (Fragaria vesca subspecies vesca 'Hawaii 4').

BackgroundThe diploid (2n = 2x = 14) strawberry model plant Fragaria vesca ssp. vesca ‘Hawaii 4’ was employed for functional analysis of expressed DNA sequences initially identified as being unique to Fragaria and of unknown or poorly understood function. ‘Hawaii 4’ is prominent in strawberry research due to its ease of Agrobacterium-mediated transformation and regenerability, and its status as the source of the first complete strawberry genomic sequence. Our studies of a set of transformants have documented intriguing, construct-associated effects on leaf morphology, and provide important and unexpected insights into the performance of the ‘Hawaii 4’ transformation and regeneration system.ResultsFollowing Agrobacterium-mediated transformation of leaf explants with gene constructs carried by Gateway® vectors, plants were regenerated using a modified version of an established ‘Hawaii 4’ protocol. Expanding upon the findings of prior studies, we documented that plantlet regeneration was occurring via a somatic embryogenic rather than an organogenic developmental pathway. Among transformants, several variations in leaf morphology were observed. Unexpectedly, a particular leaf variant type, occurring in ~17% of all regenerants independent of construct type, was found to be attributable to tetraploidy. The tetraploidy-associated alteration in leaf morphology could be differentiated from the leaf morphology of diploid regenerants on the basis of a quantitative ratio of leaf dimensions: B/A, where B is the width of the central leaflet and A is the overall width of the trifoliate leaf. Variant effects on leaf morphology of four different transgenic constructs were also documented, and were in all cases distinguishable from the effects of tetraploidy.ConclusionsThese results define opportunities to optimize the existing ‘Hawaii 4’ protocol by focusing on treatments that specifically promote somatic embryogenesis. The reported morphological metric and descriptions will guide future transgenic studies using the ‘Hawaii 4’ model system by alerting researchers to the potential occurrence of polyploid regenerants, and to differentiating the effects on leaf morphology due to polyploidy versus transgenic manipulations. Finally, an intriguing spectrum of leaf morphology alterations resulting from manipulation of expressed sequences of uncertain function is documented, providing a foundation for detailed studies of the respective genes and their functional roles.

Leaf Morphological and Stomatal Variations in Paper Birch Populations along Environmental Gradients in Canada

Variations in leaf morphology and stomatal characteristics have been extensively studied at both inter- and intraspecific levels although not explicitly in the context of paper birch (Betula papyrifera Marsh) populations. The birch populations might have developed the leaf variations that allowed them to adapt to a wide climatic gradient. Therefore, in this study we examined variations in the leaf morphological and stomatal characteristics of sixteen paper birch populations collected across Canada and grown in a common garden. We also examined the relationship between these leaf characteristics and the climate of the population’s origin. Significant genotypic differences were found in the leaf characteristics measured among the birch populations. Thus, we expected that the observed leaf variations may be partly explained as natural diversity in the birch due to differences in environment of origin. We noticed that along mean annual precipitation and aridity gradients, hair density on leaf adaxial surface had decreased whereas stomatal density increased significantly. Our results showed that the populations with larger leaf area and specific leaf area had higher hair density but low stomatal density. These leaf characteristics provided a structural basis in reducing water loss through leaves and increasing water use efficiency. A trade-off between stomatal area and density resulted in this study might be a strategy of the birch to balance stomatal conductance in decreased precipitation.

Morphological and anatomical determinants of mesophyll conductance in wild relatives of tomato (Solanum sect. Lycopersicon, sect. Lycopersicoides; Solanaceae)

Natural selection on photosynthetic performance is a primary factor determining leaf phenotypes. The complex CO2 diffusion path from substomatal cavities to the chloroplasts - the mesophyll conductance (g(m)) - limits photosynthetic rate in many species and hence shapes variation in leaf morphology and anatomy. Among sclerophyllous and succulent taxa, structural investment in leaves, measured as the leaf dry mass per area (LMA), has been implicated in decreased gm . However, in herbaceous taxa with high g(m), it is less certain how LMA impacts CO2 diffusion and whether it significantly affects photosynthetic performance. We addressed these questions in the context of understanding the ecophysiological significance of leaf trait variation in wild tomatoes, a closely related group of herbaceous perennials. Although g(m) was high in wild tomatoes, variation in g(m) significantly affected photosynthesis. Even in these tender-leaved herbaceous species, greater LMA led to reduced g(m). This relationship between g(m) and LMA is partially mediated by cell packing and leaf thickness, although amphistomy (equal distribution of stomata on both sides of the leaf) mitigates the effect of leaf thickness. Understanding the costs of increased LMA will inform future work on the adaptive significance of leaf trait variation across ecological gradients in wild tomatoes and other systems.

Taxonomic Revision of the Eurasian <I>Stipa</I> Subsections <I>Stipa</I> and <I>Tirsae</I> (Poaceae)

A comprehensive taxonomic revision of Stipa subsects. Stipa and Tirsae is presented. We analyzed the pattern of morphological variation of the taxa included in both subsections through the study of 1353 vouchers from 27 herbaria. Variation in floral and leaf morphology was further explored to revaluate taxon limits in 165 specimens using univariate analyses (Anova, Tukey test and, c 2 test), and multivariate tests (principal components analysis and discriminant analysis). We found that one species of subsect. Tirsae plus three species and five subspecies of subsect. Stipa can be distinguished based on morphological characters. For each taxon, we present a dichotomous key, a list of synonyms, detailed morphometric descriptions, illustrations, and distribution maps. In addition, neotypes are proposed for S. pulcherrima var. mollis (subsection Stipa) and S. aperta (subsection Stipa), and a lectotype is proposed for S. cerariorum (subsection Tirsae). Likewise, two new combinations are proposed: Stipa subsection Tirsae (Martinovsky ´ ) R. Gonzalo, and Stipa turkestanica subspecies macroglossa (P.A Smirn.) R. Gonzalo.