Louisiana Iris Research Articles

Genetic structure in Louisiana Iris species reveals patterns of recent and historical admixture.

When divergent lineages come into secondary contact, reproductive isolation may be incomplete, thus providing an opportunity to investigate how speciation is manifested in the genome. The Louisiana Irises (Iris, series Hexagonae) comprise a group of three or more ecologically and reproductively divergent lineages that can produce hybrids where they come into contact. We estimated standing genetic variation to understand the current distribution of population structure in the Louisiana Irises. We used genotyping-by-sequencing techniques to sample the genomes of Louisiana Iris species across their ranges. We sampled 20 populations (n = 632 individuals) across 11,249 loci and used Entropy and PCA models to assess population genetic data. We discovered evidence for interspecific gene flow in parts of the range. Our analysis revealed patterns of population structure at odds with widely accepted nominal taxonomy. We discovered undescribed hybrid populations, designated as belonging to the I. brevicaulis lineage. Iris nelsonii shared significant ancestry with only one of the purported parent species, I. fulva, evidence inconsistent with a hybrid origin. This study provides several key findings important to the investigation of standing genetic variation in the Louisiana Iris species complex. Compared to the other nominal species, I. brevicaulis contains a large amount of genetic diversity. In addition, we discovered a previously unknown hybrid zone between I. brevicaulis and I. hexagona along the Texas coast. Finally, our results do not support the long-standing hypothesis that I. nelsonii has mixed ancestry from three parental taxa.

On biodiversity and conservation of the Iris hexagona complex (Phaeiris, Iridaceae)

AbstractTaxonomic revisions using newly available molecular data can have profound consequences for identifying areas of high endemism and, therefore, high conservation priority. A good example of the connection between taxonomy, biodiversity ecology, and conservation issues is genus Phaeiris (Iris subsect. Hexagonae), an endemic taxon of the southeastern United States and in particular P. hexagona (I. hexagona) (Blue Flag), perhaps the best‐known species of this genus. Some authors recently provided evidence for the need to revise the taxonomy of the Blue Flag, which has usually been considered to consist of a single species, P. hexagona. Using molecular and bioclimatic analyses of Blue Flags from Florida and Louisiana, collected at their loci classici, we challenge the notion that P. hexagona is a single species, referring to the almost forgotten taxonomic context of Phaeiris as established by John K. Small and Edward J. Alexander nearly 90 yr ago. Our vision of the P. hexagona complex reinforces the current treatment of Southern Coastal Plain as a biodiversity hotspot. Our results also argue for the complex nature of endemism on the Florida Peninsula, and elsewhere on the Southern Coastal Plain, including a new interpretation of the well‐studied Louisiana irises. We also propose that the valleys of Florida rivers and lakes are likely to harbor additional hidden biodiversity. Accurate taxonomy proved to be a heuristic tool to characterize better the actual level of biodiversity within Southern Coastal Plain as well as to describe the different areas endemism. The newly re‐documented taxonomic diversity in broadly defined P. hexagona should also be considered in future conservation efforts.

Oh, what a tangled web we weave

Oh, what a tangled web we weave

Integrating Bayesian genomic cline analyses and association mapping of morphological and ecological traits to dissect reproductive isolation and introgression in a Louisiana Iris hybrid zone.

Hybrid zones provide unique opportunities to examine reproductive isolation and introgression in nature. We utilized 45,384 single nucleotide polymorphism (SNP) loci to perform association mapping of 14 floral, vegetative and ecological traits that differ between Iris hexagona and Iris fulva, and to investigate, using a Bayesian genomic cline (BGC) framework, patterns of genomic introgression in a large and phenotypically diverse hybrid zone in southern Louisiana. Many loci of small effect size were consistently found to be associated with phenotypic variation across all traits, and several individual loci were revealed to influence phenotypic variation across multiple traits. Patterns of genomic introgression were quite heterogeneous throughout the Louisiana Iris genome, with I.hexagona alleles tending to be favoured over those of I. fulva. Loci that were found to have exceptional patterns of introgression were also found to be significantly associated with phenotypic variation in a small number of morphological traits. However, this was the exception rather than the rule, as most loci that were associated with morphological trait variation were not significantly associated with excess ancestry. These findings provide insights into the complexity of the genomic architecture of phenotypic differences and are a first step towards identifying loci that are associated with both trait variation and reproductive isolation in nature.

Green Period Characteristics and Foliar Cold Tolerance in 12 Iris Species and Cultivars in the Yangtze Delta, China

Iris (Iris sp.) is a popular and widely planted herbaceous perennial. However, most iris species go dormant without any aesthetic quality for 5–6 months in the transition zone between the temperate and subtropical climates. To investigate the effects of species/cultivars, leaf shape, and air temperature conditions on the ability to stay green, 12 popular species and cultivars in the transition zone were evaluated. Iris tested included the following species: roof iris (I. tectorum), japanese iris (I. japonica), long leafed flag (I. halophila), yellow flag (I. pseudacorus), blood iris (I. sanguinea), japanese water iris (I. ensata), and small-flower iris (I. speculatrix) and the following cultivars: ‘Chinensis’ milky iris (I. lactea var. chinensis), ‘Bryce Leigh’ louisiana iris (I. hexagonae), ‘Black Swan’ german iris (I. germanica), ‘Careless Sally’ siberian iris (I. sibirica), and ‘Loyalty’ japanese water iris (I. ensata). We conducted a 2-year field study on mature iris populations and evaluated the percentage of green leaves during winter retention and spring recovery using a digital image analysis (DIA). Green period during this study was calculated using predicted sigmoid curves based on the percentage of green leaves. The present study revealed that iris species/cultivars and air temperatures had considerable influence on the duration of the green period. Both evergreen and deciduous iris phenotypes exist with three different leaf shapes, among which the average green period of fan-shaped leaf iris species and cultivars was the longest. Because there was no significant (P = 0.205) relationship between green period during this period and leaf lethal temperature (LT50), new cultivars with long green periods may be achieved without a simultaneous loss of cold tolerance in iris.

Hybridization between ecotypes in a phenotypically and ecologically heterogeneous population of Iris savannarum (Iridaceae) in Florida

Iris series Hexagonae is a small, monophyletic complex of five species and associated hybrid populations, popularly known as the ‘Louisiana irises’. Series Hexagonae has been recognized as a textbook case of introgressive hybridization based on numerous studies in Louisiana. We previously explored patterns of genetic structure and diversity in populations of the complex in Florida. Populations that occupy high, dry habitats have plants with a distinctive floral ‘highlands’ phenotype. Aquatic populations of I. savannarum also have a consistent floral phenotype (‘coastal’). Jacks Branch slough in Glades County harbors the largest population of series Hexagonae sampled in our previous studies. It is an ecologically heterogeneous site, punctuated by sandy uplands that remain above high water and harbor Iris with the highlands floral phenotype as well as coastal types in the wetter areas of the slough. We hypothesized that mesic, but non‐inundated, sites in the slough would host hybrids of the two phenotypic groups, and tested these hypotheses with 19 microsatellite loci. All data analyses support our hypothesis of hybridization between the upland and hydric subpopulations. Although two methods of introgression analysis identify some of the individuals from the admixture zone as first‐generation hybrids, subsequent admixture was asymmetric with introgression from the ‘highland’ parent. This is the first report of such assortative processes occurring in the confines of a single population of Iris. We suggest that the evolutionary processes described interspecifically for series Hexagonae commence early at the population level.

Niche Conservatism for Ecological Preference in the Louisiana iris species complex.

Spatial and temporal environmental variation influences evolutionary processes such as divergence among populations and species. Here, we investigate the patterns of niche evolution for the Louisiana irises as well as understanding the phylogenetic relationship between these species. Using BEAST, a species phylogeny was generated for the Louisiana irises in order to test the hypothesis of whether niche conservatism has played an important role for this species complex. Species Distribution Models were constructed for present day distributions to determine the environmental factors, which contribute to species ranges. Tests of niche similarity were performed in order to evaluate if niche conservatism is apparent within this species complex. We demonstrate that the Louisiana iris species complex is a monophyletic clade with I. brevicaulis and I. fulva as being sister to each other. The differences observed among the iris species, in regard to associated environmental factors suggest an effect from these components on the distributions and habitats occupied. Furthermore, tests of niche similarity indicate niche conservatism for all species comparisons. Working at the species level and assessing various factors that can influence differentiation, this study assessed a more complete picture of the ecological and evolutionary history of this species complex across their geographic and ecological range.

Transcriptome Profiling of Louisiana iris Root and Identification of Genes Involved in Lead-Stress Response.

Louisiana iris is tolerant to and accumulates the heavy metal lead (Pb). However, there is limited knowledge of the molecular mechanisms behind this feature. We describe the transcriptome of Louisiana iris using Illumina sequencing technology. The root transcriptome of Louisiana iris under control and Pb-stress conditions was sequenced. Overall, 525,498 transcripts representing 313,958 unigenes were assembled using the clean raw reads. Among them, 43,015 unigenes were annotated and their functions classified using the euKaryotic Orthologous Groups (KOG) database. They were divided into 25 molecular families. In the Gene Ontology (GO) database, 50,174 unigenes were categorized into three GO trees (molecular function, cellular component and biological process). After analysis of differentially expressed genes, some Pb-stress-related genes were selected, including biosynthesis genes of chelating compounds, metal transporters, transcription factors and antioxidant-related genes. This study not only lays a foundation for further studies on differential genes under Pb stress, but also facilitates the molecular breeding of Louisiana iris.

Determining population structure and hybridization for two iris species

Identifying processes that promote or limit gene flow can help define the ecological and evolutionary history of a species. Furthermore, defining those factors that make up “species boundaries” can provide a definition of the independent evolutionary trajectories of related taxa. For many species, the historic processes that account for their distribution of genetic variation remain unresolved. In this study, we examine the geographic distribution of genetic diversity for two species of Louisiana Irises, Iris brevicaulis and Iris fulva. Specifically, we asked how populations are structured and if population structure coincides with potential barriers to gene flow. We also asked whether there is evidence of hybridization between these two species outside Louisiana hybrid zones. We used a genotyping-by-sequencing approach and sampled a large number of single nucleotide polymorphisms across these species' genomes. Two different population assignment methods were used to resolve population structure in I. brevicaulis; however, there was considerably less population structure in I. fulva. We used a species tree approach to infer phylogenies both within and between populations and species. For I. brevicaulis, the geography of the collection locality was reflected in the phylogeny. The I. fulva phylogeny reflected much less structure than detected for I. brevicaulis. Lastly, combining both species into a phylogenetic analysis resolved two of six populations of I. brevicaulis that shared alleles with I. fulva. Taken together, our results suggest major differences in the level and pattern of connectivity among populations of these two Louisiana Iris species.

QTL mapping reveals the genetic architecture of loci affecting pre- and post-zygotic isolating barriers in Louisiana Iris

BackgroundHybridization among Louisiana Irises has been well established and the genetic architecture of reproductive isolation is known to affect the potential for and the directionality of introgression between taxa. Here we use co-dominant markers to identify regions where QTL are located both within and between backcross maps to compare the genetic architecture of reproductive isolation and fitness traits across treatments and years.ResultsQTL mapping was used to elucidate the genetic architecture of reproductive isolation between Iris fulva and Iris brevicaulis. Homologous co-dominant EST-SSR markers scored in two backcross populations between I. fulva and I. brevicaulis were used to generate genetic linkage maps. These were used as the framework for mapping QTL associated with variation in 11 phenotypic traits likely responsible for reproductive isolation and fitness. QTL were dispersed throughout the genome, with the exception of one region of a single linkage group (LG) where QTL for flowering time, sterility, and fruit production clustered. In most cases, homologous QTL were not identified in both backcross populations, however, homologous QTL for flowering time, number of growth points per rhizome, number of nodes per inflorescence, and number of flowers per node were identified on several linkage groups.ConclusionsTwo different traits affecting reproductive isolation, flowering time and sterility, exhibit different genetic architectures, with numerous QTL across the Iris genome controlling flowering time and fewer, less distributed QTL affecting sterility. QTL for traits affecting fitness are largely distributed across the genome with occasional overlap, especially on LG 4, where several QTL increasing fitness and decreasing sterility cluster. Given the distribution and effect direction of QTL affecting reproductive isolation and fitness, we have predicted genomic regions where introgression may be more likely to occur (those regions associated with an increase in fitness and unlinked to loci controlling reproductive isolation) and those that are less likely to exhibit introgression (those regions linked to traits decreasing fitness and reproductive isolation).

The Genetic Mosaic ofIrisSeriesHexagonaein Florida: Inferences on the Holocene History of the Louisiana Irises and Anthropogenic Effects on Their Distribution

Iris series Hexagonae is a small, monophyletic complex of five species and associated hybrid populations, popularly known as the “Louisiana irises.” The Hexagonae alliance of Iris has been recognized as a textbook case of introgressive hybridization on the basis of numerous studies in Louisiana. In light of field observations of phenotypic heterogeneity among Florida populations, we investigated genetic variation within and among 37 populations of Iris series Hexagonae from Florida, seven from Louisiana, and one from Texas with 19 microsatellite loci. We wished to test the hypothesis that the Lake Wales Ridge and Polk Uplands of Florida, which remained above sea level maxima during the early Pleistocene, might be the sites of origin for all extant iris populations in Florida and possibly the series Hexagonae in its entirety. We also hypothesized that phenotypic heterogeneity observed in Florida iris would be reflected in patterns of allelic diversity. Finally, we wished to seek evidence of Native American influence on the present distribution of iris in Florida. Most populations display clonality, including three populations that are predominantly one or two clones. Levels of gene diversity are high and the populations are highly differentiated, although 19 exhibit significant homozygote excess. The majority of genetic variation occurs within populations. Genetic distance resolves three large clusters. One unites the southernmost populations with those from north-central Gulf coastal Florida. A second encompasses southwest Gulf coastal populations. If three compound repeat loci are dropped from the data, these two clusters are united. The third group joins populations derived from the Central Highlands of peninsular Florida, which are genetically isolated from all other peninsular Florida populations, with populations of Iris fulva, Iris brevicaulis, Iris giganticaerulea, and Iris hexagona s.s., supporting recognition of the latter two as distinct species. Model-based Bayesian clustering supports high population differentiation () and isolation of Central Highlands populations, and it resolves the terminal clusters of the genetic distance topology. Isolation by distance is significant yet weak because of genetic distance relationships that contradict biogeographic expectations. We propose that the Lake Wales Ridge and Polk Uplands, which constituted the Wicomico shoreline during an early Pleistocene interglacial inundation, functioned as refugia for series Hexagonae. Moreover, we suggest that Florida iris populations occupying high, dry habitats close to the Central Highlands ridges represent relicts of once-larger populations that adapted to the more xeric condition during the last glacial maximum. These populations have a distinctive floral phenotype and are related to species of Hexagonae iris outside of peninsular Florida. Excessively clonal populations may have been deliberately cultivated by Native Americans, which may also have influenced the connection between southern and north-central Florida populations, but there is insufficient evidence to validate this hypothesis. Many populations test positively for recent bottlenecks, which we attribute primarily to founder effects, given the low migration rates of the species and the high degree of population differentiation as well as the Holocene geological history of the Florida peninsula. We present evidence of peripatric divergence in series Hexagonae iris and suggest that this may function as a significant generator of species diversity in the group.

Hybrid fitness, adaptation and evolutionary diversification: lessons learned from Louisiana Irises

Estimates of hybrid fitness have been used as either a platform for testing the potential role of natural hybridization in the evolution of species and species complexes or, alternatively, as a rationale for dismissing hybridization events as being of any evolutionary significance. From the time of Darwin's publication of The Origin, through the neo-Darwinian synthesis, to the present day, the observation of variability in hybrid fitness has remained a challenge for some models of speciation. Yet, Darwin and others have reported the elevated fitness of hybrid genotypes under certain environmental conditions. In modern scientific terminology, this observation reflects the fact that hybrid genotypes can demonstrate genotype × environment interactions. In the current review, we illustrate the development of one plant species complex, namely the Louisiana Irises, into a 'model system' for investigating hybrid fitness and the role of genetic exchange in adaptive evolution and diversification. In particular, we will argue that a multitude of approaches, involving both experimental and natural environments, and incorporating both manipulative analyses and surveys of natural populations, are necessary to adequately test for the evolutionary significance of introgressive hybridization. An appreciation of the variability of hybrid fitness leads to the conclusion that certain genetic signatures reflect adaptive evolution. Furthermore, tests of the frequency of allopatric versus sympatric/parapatric divergence (that is, divergence with ongoing gene flow) support hybrid genotypes as a mechanism of evolutionary diversification in numerous species complexes.

Transmission ratio distortion results in asymmetric introgression in Louisiana Iris.

BackgroundLinkage maps are useful tools for examining both the genetic architecture of quantitative traits and the evolution of reproductive incompatibilities. We describe the generation of two genetic maps using reciprocal interspecific backcross 1 (BC1) mapping populations from crosses between Iris brevicaulis and Iris fulva. These maps were constructed using expressed sequence tag (EST)- derived codominant microsatellite markers. Such a codominant marker system allowed for the ability to link the two reciprocal maps, and compare patterns of transmission ratio distortion observed between the two.ResultsLinkage mapping resulted in markers that coalesced into 21 linkage groups for each of the reciprocal backcross maps, presumably corresponding to the 21 haploid chromosomes of I. brevicaulis and I. fulva. The composite map was 1190.0-cM long, spanned 81% of the I. brevicaulis and I. fulva genomes, and had a mean density of 4.5 cM per locus. Transmission ratio distortion (TRD) was observed in 138 (48.5%) loci distributed in 19 of the 21 LGs in BCIB, BCIF, or both BC1 mapping populations. Of the distorted markers identified, I. fulva alleles were detected at consistently higher-than-expected frequencies in both mapping populations.ConclusionsThe observation that I. fulva alleles are overrepresented in both mapping populations suggests that I. fulva alleles are favored to introgress into I. brevicaulis genetic backgrounds, while I. brevicaulis alleles would tend to be prevented from introgressing into I. fulva. These data are consistent with the previously observed patterns of introgression in natural hybrid zones, where I. fulva alleles have been consistently shown to introgress across species boundaries.

Asymmetric introgressive hybridization among louisiana iris species.

In this review, we discuss findings from studies carried out over the past 20+ years that document the occurrence of asymmetric introgressive hybridization in a plant clade. In particular, analyses of natural and experimental hybridization have demonstrated the consistent introgression of genes from Iris fulva into both Iris brevicaulis and Iris hexagona. Furthermore, our analyses have detected certain prezygotic and postzygotic barriers to reproduction that appear to contribute to the asymmetric introgression. Finally, our studies have determined that a portion of the genes transferred apparently affects adaptive traits.

THE GENETIC ARCHITECTURE OF REPRODUCTIVE ISOLATION IN LOUISIANA IRISES: HYBRID FITNESS IN NATURE

Negative epistasis in hybrid genomes commonly results in postzygotic isolation between divergent lineages. However, some genomic regions may be selectively neutral or adaptive in hybrids and thus may potentially cross species barriers. We examined postzygotic isolation between ecologically similar species of Louisiana Iris: Iris brevicaulis and I. fulva to determine the potential for adaptive introgression in nature. Line-cross analyses allowed us a general overview of the gene action responsible for fitness-related traits. We then used a QTL mapping approach to detect genomic regions responsible for variation in these traits. Although hybrid classes suffered reduced fitness for many traits, hybrid means were equivalent to at least one of the parental species in overall estimates of maternal and paternal fitness during the two years of the field study. The genetic architecture underlying the fitness-related traits varied across field site and year of the study, thus emphasizing the importance of the environment in determining the degree of postzygotic isolation and potential for introgression across natural hybrid zones.

EST and EST-SSR marker resources for Iris

BackgroundLimited DNA sequence and DNA marker resources have been developed for Iris (Iridaceae), a monocot genus of 200–300 species in the Asparagales, several of which are horticulturally important. We mined an I. brevicaulis-I. fulva EST database for simple sequence repeats (SSRs) and developed ortholog-specific EST-SSR markers for genetic mapping and other genotyping applications in Iris. Here, we describe the abundance and other characteristics of SSRs identified in the transcript assembly (EST database) and the cross-species utility and polymorphisms of I. brevicaulis-I. fulva EST-SSR markers among wild collected ecotypes and horticulturally important cultivars.ResultsCollectively, 6,530 ESTs were produced from normalized leaf and root cDNA libraries of I. brevicaulis (IB72) and I. fulva (IF174), and assembled into 4,917 unigenes (1,066 contigs and 3,851 singletons). We identified 1,447 SSRs in 1,162 unigenes and developed 526 EST-SSR markers, each tracing a different unigene. Three-fourths of the EST-SSR markers (399/526) amplified alleles from IB72 and IF174 and 84% (335/399) were polymorphic between IB25 and IF174, the parents of I. brevicaulis × I. fulva mapping populations. Forty EST-SSR markers were screened for polymorphisms among 39 ecotypes or cultivars of seven species – 100% amplified alleles from wild collected ecotypes of Louisiana Iris (I.brevicaulis, I.fulva, I. nelsonii, and I. hexagona), whereas 42–52% amplified alleles from cultivars of three horticulturally important species (I. pseudacorus, I. germanica, and I. sibirica). Ecotypes and cultivars were genetically diverse – the number of alleles/locus ranged from two to 18 and mean heterozygosity was 0.76.ConclusionNearly 400 ortholog-specific EST-SSR markers were developed for comparative genetic mapping and other genotyping applications in Iris, were highly polymorphic among ecotypes and cultivars, and have broad utility for genotyping applications within the genus.

Hybridization, hybrid fitness and the evolution of adaptations

This review focuses on two related outcomes of hybridization sensu lato (i.e. findings from both natural and experimental hybrids are discussed): (1) the production of hybrid genotypes with various fitnesses, and (2) the origin/transfer of adaptations in the Louisiana Iris species complex. Since effects on fitness, and the origin or transfer of adaptations, are of fundamental evolutionary importance, the examples discussed in this review reflect some of the most significant phenomena deriving from the transfer of genetic material via natural hybridization.

Nutrient Recovery by Seven Aquatic Garden Plants in a Laboratory-scale Subsurface-constructed Wetland

Commercial nurseries use large amounts of water and nutrients to produce container-grown plants. The large volume of runoff containing nitrogen (N) and phosphorus (P) that leaves nurseries can contaminate surface and groundwater. Subsurface flow-constructed wetlands have been shown to effectively treat agricultural, industrial, and residential wastewater and to be well-suited for growers with limited production space. We investigated the possibility of using commercially available aquatic garden plants in subsurface-constructed wetlands to remove nutrients in a laboratory scale, gravel-based system. Seven popular aquatic garden plants received N and P from Hoagland's nutrient solution every 2 days for 8 weeks. These rates (0.39 to 36.81 mg·L−1 of N and 0.07 to 6.77 mg·L−1 P, respectively) encompassed low to high rates of nutrients found at various points between the discharge and inflow points of other constructed wetland systems currently in use at commercial nurseries. Plant biomass, nutrient recovery, and tissue nutrient concentration and content were measured. Whole plant dry weight positively correlated with total N and P supplied. Louisiana Iris hybrid ‘Full Eclipse’, Canna × generalis Bailey (pro sp.) ‘Bengal Tiger’, Canna × generalis Bailey (pro sp.) ‘Yellow King Humbert’, Colocasia esculenta (L.) Schott ‘Illustris', Peltandra virginica (L.) Schott, and Pontederia cordata L. ‘Singapore Pink’ had the greatest N recovery rates. The P recovery rates were similar for the cannas, Colocasia esculenta ‘Illustris’, Louisiana Iris ‘Full Eclipse’, Pe. virginica, and Po. cordata ‘Singapore Pink’. The potential exists for creating a sustainable nursery and greenhouse production system that incorporates a subsurface-constructed wetland planted with marketable horticultural crops that provide remediation and revenue.

QTL ANALYSIS OF FLORAL TRAITS IN LOUISIANA IRIS HYBRIDS

The formation of hybrid zones between nascent species is a widespread phenomenon. The evolutionary consequences of hybridization are influenced by numerous factors, including the action of natural selection on quantitative trait variation. Here we examine how the genetic basis of floral traits of two species of Louisiana Irises affects the extent of quantitative trait variation in their hybrids. Quantitative trait locus (QTL) mapping was used to assess the size (magnitude) of phenotypic effects of individual QTL, the degree to which QTL for different floral traits are colocalized, and the occurrence of mixed QTL effects. These aspects of quantitative genetic variation would be expected to influence (1) the number of genetic steps (in terms of QTL substitutions) separating the parental species phenotypes; (2) trait correlations; and (3) the potential for transgressive segregation in hybrid populations. Results indicate that some Louisiana Iris floral trait QTL have large effects and QTL for different traits tend to colocalize. Transgressive variation was observed for six of nine traits, despite the fact that mixed QTL effects influence few traits. Overall, our QTL results imply that the genetic basis of floral morphology and color traits might facilitate the maintenance of phenotypic divergence between Iris fulva and Iris brevicaulis, although a great deal of phenotypic variation was observed among hybrids.

Iris Fulva 'Louisiana Hybrids' Louisiana Iris

Iris Fulva 'Louisiana Hybrids' Louisiana Iris