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The Conservation Status of Trillium in North America

Authors:
Clayton Meredith at New Mexico BioPark Society
Clayton Meredith
  • New Mexico BioPark Society
Anne Frances at United States Department of Agriculture
Anne Frances
Amy Highland at United States Botanic Garden
Amy Highland
  • United States Botanic Garden
Leah Oliver
Leah Oliver
Leah Oliver
  • This person is not on ResearchGate, or hasn't claimed this research yet.
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Abstract and Figures

The genus Trillium is made up of about 50 species worldwide with concentrations in eastern and western North America and eastern Asia. The diversity of Trillium in North America warrants special recognition because both the Pacific Northwest and the eastern half of the United States are centers of endemism for the genus1. Identifying the conservation needs of the genus is a high priority given recent taxonomic changes within the family, the number of species with small ranges which could be conserved through relatively minor interventions, and the need for coordinating action between a variety of conservation organizations. Assessment of the conservation status of Trillium is considered here to be a first step in the development of comprehensive conservation action plans for under-conserved members of the genus.
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... Its taxonomy is in flux (e.g. a prior taxonomic history as a genus in the Liliaceae; Zomlefer et al., 2001) owing to the recent discovery of rare, endemic species and the reclassification of established species in segregated genera. Currently, there are ~50 recognized species, with the greatest diversity and majority of them in North America (Meredith et al., 2022). All species of Trillium produce a solitary three-part flower and are classified into four subgenera (Lampley et al., 2022): three subgenera that include pedicellate-flowered species (subgen. ...
Exploring geography and evolutionary history as drivers of variation in floral scent chemistry in western sessile-flowered Trillium using parsimony-constrained phylogenetics
Article
  • Jul 2024
  • ANN BOT-LONDON
Background and Aims The sessile-flowered Trillium species from western North America have been challenging to distinguish morphologically owing to overlapping characters and intraspecific variation. Molecular phylogenetic analyses, currently inconclusive for this group, have not sampled multiple populations of the different species to account for this. Here, we query the diversity of floral volatile composition to understand its bearings on the taxonomy, distribution and evolution of this group. Methods We explored taxonomic and geographical patterns in average floral volatile composition (105 different compounds) among 42 wild populations of four sessile-flowered Trillium species and the outgroup, Pseudotrillium, in California, Oregon and Washington, by means of parsimony-constrained phylogenetic analyses. To assess the influence of character construction, we coded compound abundance in three different ways for the phylogenetic analyses and compared the results with those of statistical analyses using the same dataset and previously published statistical analyses. Key Results Different codings of floral volatile composition generated different phylogenetic topologies with different levels of resolution. The different phylogenies provide similar answers to taxonomic questions but support different evolutionary histories. Monophyly of most populations of each taxon suggests that floral scent composition bears phylogenetic signal in the western sessile-flowered Trillium. Lack of correlation between the distribution of populations and their position in scent-based phylogenies does not support a geographical signal in floral scent composition. Conclusions Floral scent composition is a valuable data source for generating phylogenetic hypotheses. The way in which scent composition is coded into characters is important. The phylogenetic patterns supported by floral volatile compounds are incongruent with previously reported phylogenies of the western sessile-flowered Trillium obtained using molecular or morphological data. Combination of floral scent data with gene sequence data and detailed morphological data from multiple populations of each species in future studies is needed for understanding the evolutionary history of western sessile-flowered Trillium.
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Studies in the vascular flora of the southeastern United States. VI
Article
Full-text available
  • Dec 2020
As part of ongoing efforts to understand, document, and conserve the flora of southeastern North America, we propose a number of taxo-nomic changes, nomenclatural changes, interpretations of nativity, and distributional accounts. Regarding the Asaroideae (Aristolochiaceae), we support continued recognition of Hexastylis (and other segregates of a very broad Asarum s.l.) at generic rank and make the necessary combinations to continue the use of Hexastylis in southeastern North America floras. In Conoclinium (Asteraceae), we present morphological and distributional evidence corroborating the recent suggestion (based on molecular evidence) that Chapman's 1878 C. dichotomum is distinct, warrants recognition, and is present as a second Conoclinium in the southeastern North American flora. An analysis of historical accounts of Gaillardia pulchella (Asteraceae) strongly suggests that its modern occurrence east of Texas is adventive, rather than native. Two rare southeastern United States skullcaps, Scutellaria mellichampii and S. ocmulgee (Lamiaceae), have been persistently confused with one another and other species; we present a reassessment of the taxonomic distinction between them, best ways to distinguish them and similar species, and their known distributions. A reassessment of the taxonomy, distribution, and ecology of Linum carteri (Linaceae), a rare southern Florida endemic, confirms that two species should be recognized by modern species concepts; we make the necessary new combination to effect the recognition of two narrowly endemic species. In Andropogon (Poaceae), we propose that A. virginicus var. decipiens warrants recognition as distinct at species rank from other entities in the Andropogon virginicus complex. We also present more comprehensive information on the distributions of four species of "bushy bluestems" (Andropogon glomeratus s.l.), their ecology, and their practical recognition. In the Violaceae, modern reassessment of the taxonomy of many species (especially in the genus Viola) by H.E. Ballard, Jr. and collaborators have been vexed by uncertain application of many "old" names; we here provide a first installment of typifications and nomenclatural interpretations needed to move forward with a modern treatment of the genus in our region. In Xyris (Xyridaceae), we re-establish the generally ignored X. elliottii var. stenotera based on careful and extensive study of its morphology and ecology in comparison to X. elliottii var. elliottii, This article has been licensed as Open Access by the author(s) and publisher. This version supersedes any other version with conflicting usage rights. 200 Journal of the Botanical Research Institute of Texas 14(2) including a transplant study. English naturalist Mark Catesby (1683-1749) has been honored by having a genus and fifteen species of plants named for him, but most of these honorific names have been cons tructed in manners contrary to the Shenzhen Code; as these are "errors to be corrected," we therefore propose to correct and standardize these honorifics by restoring his name "catesby-" as the root of the names. Similarly, in seven names (variably formed) employed by W.W Ashe to honor his cousin and (later) wife Margaret Haywood Henry (Wilcox) (Ashe), we also standardize and correct the root of the names to be accurately based on her name, "margaret-," in conformance with the Shenzhen Code. resumen Como parte de los esfuerzos en marcha para entender, documentar, y conservar la flora del sudeste de Norte América, proponemos un número de cambios taxonómicos, nomenclaturales, interpretaciones de ser autóctonas, y datos de distribución. En relación con Asaroideae (Aristolochiaceae), continuamos reconociendo en el rango genérico Hexastylis (y otros segregados del muy amplio Asarum s.l.) y hacemos las combinaciones necesarias para continuar con el uso de Hexastylis en la flora del sudeste de Norte América. En Conoclinium (Asteraceae), presentamos pruebas morfológicas y de distribución que corroboran la reciente sugestión (basada en pruebas moleculares) que C. dichoto-mum de Chapman 1878 es distinta, merece reconocimiento, y está presente como una segunda Conoclinium en la flora del sudeste de Norte América. Un análisis de las citas históricas de Gaillardia pulchella (Asteraceae) sugiere fuertemente que su moderna ocurrencia en el este de Texas es adventicia, en vez de nativa. Dos especies raras del sudeste de Estados Unidos, Scutellaria mellichampii y S. ocmulgee (Lamiaceae), han sido permanentemente confundidas con otra y otras especies; presentamos una reevaluación de la distinción taxonómica entre ellas, el mejor modo de distinguirlas entre ellas y con especies similares, y sus distribuciones conocidas. Una reevaluación de la taxonomía, distri-bución, y ecología de Linum carteri (Linaceae), un endemismo raro del sur de Florida, confirma que deben reconocerse dos especies según los modernos conceptos de especie; hacemos las nuevas combinaciones necesarias para efectuar el reconocimiento de dos especies endémi-cas restringidas. En Andropogon (Poaceae), proponemos que A. virginicus var. decipiens precisa reconocimiento en el rango de especie como distinta de otras entidades en el complejo Andropogon virginicus. También presentamos información más completa de las distribuciones de cuatro especies de "bushy bluestems" (Andropogon glomeratus s.l.), su ecología, y su reconocimiento práctico. En la revaluación moderna de la taxonomía de Violaceae, muchas especies (especialmente en el género Viola) por H.E. Ballard, Jr. y colaboradores han sido controvertidas por la aplicación incierta de muchos nombres "viejos"; aquí aportamos una primera entrega de tipificaciones y las interpretaciones nomen-claturales necesarias para avanzar con un tratamiento moderno del género en nuestra región. En Xyris (Xyridaceae), reestablecemos la generalmente ignorada X. elliottii var. stenotera basados en un estudio cuidadoso y extensivo de su morfología y ecología en comparación con X. elliottii var. elliottii, incluyendo un estudio de trasplantes. El naturalista inglés Mark Catesby (1683-1749) ha sido distinguido por tener un género y quince especies de plantas nombradas por él, pero la mayor parte de estos nombres honoríficos han sido construidos de un modo contario al Código de Shenzhen; como estos son "errores a ser corregidos," proponemos por ello corregir y estandardizarlos restau-rando su nombre 'catesby-' como raíz de los nombres. Similarmente, en siete nombres (formados variablemente) empleados por W.W Ashe para honrar a su prima y (posterior) esposa Margaret Haywood Henry (Wilcox) (Ashe), también estandarizamos y corregimos la raíz de nombres para que estén basados con precisión en su nombre, 'margaret-,' de acuerdo con el Código de Shenzhen.
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Trillium hibbersonii (Melanthiaceae), a phylogenetically distinct species from western North America
Article
Full-text available
  • Mar 2020
Trillium Linnaeus (1753: 339) species have a reputation for being difficult to distinguish from one another, both on morphological (e.g. Freeman 1985, Schilling et al. 2019) and initial studies with standard plastid markers (Osaloo et al. 1999). Thus, the species that is sister to the rest of the Parideae, Pseudotrillium rivale (Watson 1885: 378) Farmer (2002: 687), was only recognized to be distinctive after DNA sequence data became available (Farmer & Schilling 2002). In the somewhat similar case discussed here, an entity that was considered to be only a form or variety of one species, T. ovatum Pursh (1803: 216), has turned out to be so genetically distinct that it is not even placed in the same clade as T. ovatum (Farmer 2006, Lampley et al. unpubl.).
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Changing wildfire, changing forests: the effects of climate change on fire regimes and vegetation in the Pacific Northwest, USA
Article
Full-text available
  • Dec 2020
Background Wildfires in the Pacific Northwest (Washington, Oregon, Idaho, and western Montana, USA) have been immense in recent years, capturing the attention of resource managers, fire scientists, and the general public. This paper synthesizes understanding of the potential effects of changing climate and fire regimes on Pacific Northwest forests, including effects on disturbance and stress interactions, forest structure and composition, and post-fire ecological processes. We frame this information in a risk assessment context, and conclude with management implications and future research needs. Results Large and severe fires in the Pacific Northwest are associated with warm and dry conditions, and such conditions will likely occur with increasing frequency in a warming climate. According to projections based on historical records, current trends, and simulation modeling, protracted warmer and drier conditions will drive lower fuel moisture and longer fire seasons in the future, likely increasing the frequency and extent of fires compared to the twentieth century. Interactions between fire and other disturbances, such as drought and insect outbreaks, are likely to be the primary drivers of ecosystem change in a warming climate. Reburns are also likely to occur more frequently with warming and drought, with potential effects on tree regeneration and species composition. Hotter, drier sites may be particularly at risk for regeneration failures. Conclusion Resource managers will likely be unable to affect the total area burned by fire, as this trend is driven strongly by climate. However, fuel treatments, when implemented in a spatially strategic manner, can help to decrease fire intensity and severity and improve forest resilience to fire, insects, and drought. Where fuel treatments are less effective (wetter, high-elevation, and coastal forests), managers may consider implementing fuel breaks around high-value resources. When and where post-fire planting is an option, planting different genetic stock than has been used in the past may increase seedling survival. Planting seedlings on cooler, wetter microsites may also help to increase survival. In the driest topographic locations, managers may need to consider where they will try to forestall change and where they will allow conversions to vegetation other than what is currently dominant.
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Clonal diversity and spatial genetic structure in the long-lived herb, Prairie trillium
Article
Full-text available
Combining population genetic studies with demographic surveys in long-lived clonal herbs can yield insight into the population dynamics of clonal plant populations. In this study, we assayed clonal diversity and spatial genetic structure in a population of a long-lived understory herb, Trillium recurvatum, that has been the focus of a demographic study spanning 26 years at the Meeman Biological Station in Memphis, Tennessee, USA. Using a set of five newly developed simple sequence repeat markers first reported here, we assessed 1) the extent of clonal diversity within the Meeman site, 2) the degree to which genetic diversity varies with stage class (juvenile, non-flowering, and flowering adults) at this site, 3) whether there is spatial genetic structure at the Meeman site, and 4) how measures of genetic diversity and inbreeding at the Meeman site compare to two additional nearby populations. Along with these analyses, we calculated and compared traditional population genetic metrics with information theory-based diversity indices. Although clonal propagation was present, the focal population displayed moderate levels of clonal diversity comprising 81 genets from the 174 individuals sampled. In the focal site, we also found that genetic diversity was highest in the flowering stage class when compared to the non-flowering and juvenile classes. We report that genets exhibited spatial genetic structure in the focal site exhibiting values for the Sp statistic of 0.00199 for linear distance and 0.0271 for log distance. Measures of unbiased gene diversity and the inbreeding coefficient were comparable across the sampled populations. Our results provide complementary genetic data to previous demographic studies in T. recurvatum, and these findings provide data for future studies aimed at integrating the degree of clonality, genetic variation, and population dynamics in this species. Our findings suggest that T. recurvatum at the focal Meeman site displays higher levels of sexual reproduction than were previously suggested, and spatial genetic structure estimates were comparable to other plant species with mixed and outcrossing mating strategies.
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New combinations, rank changes, and nomenclatural and taxonomic comments in the Vascular Flora of the Southeastern United States. IV
Article
Full-text available
  • Nov 2018
As part of ongoing efforts to understand and document the flora of the southeastern United States, we propose a number of taxonomic changes and report a distributional record. In Rhynchospora (Cyperaceae), we elevate the well-marked R. glomerata var. angusta to species rank. In Dryopteris (Dryopteridaceae), we report a state distributional record for Mississippi for D. celsa, filling a range gap. In Oe nothera (Onagraceae), we continue the reassessment of the Oenothera fruticosa complex and elevate O. fruticosa var. unguiculata to species rank. In Eragrostis (Poaceae), we address typification issues. In the Trilliaceae, Trillium undulatum is transferred to Trillidium, providing a better correlation of taxonomy with our current phylogenetic understanding of the family.
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Overall seed dispersal effectiveness is lower in endemic Trillium species than in their widespread congeners
Article
Full-text available
  • Nov 2018
Premise of the Study Comparing ecological attributes of endemic species with related, widespread species can reveal differences accounting for rarity. Forests of the southeastern United States are home to many range‐restricted endemic and widespread species of Trillium, a genus of ant‐dispersed herbs. Evidence suggests that aspects of seed‐related life history stages are often correlated with plant rarity, but few studies have tested whether the process of seed dispersal differs for endemic and widespread species. To address this question, we compared aspects of seed dispersal effectiveness (SDE) for three sympatric, widespread endemic Trillium species pairs. Methods We observed seed dispersal for Trillium species pairs by ants at eight sites, recorded numbers of seeds dispersed and dispersal distances, and described disperser interactions. To test disperser preference, we presented seeds of each pair to captive colonies of Aphaenogaster picea, a keystone disperser. Seeds were assigned scores based on worker behavior, and we recorded proportions of seeds dispersed after 1 h and 24 h. Key Results Field observations yielded some significant within‐pair differences. Ants dispersed more seeds of widespread species for all pairs, although dispersal distances did not differ. In laboratory experiments, after 24 h, ants dispersed more seeds of widespread species into nests. Conclusions Endemic Trillium species had lower overall SDE than did their widespread congeners. These findings add to the list of ecological and demographic challenges that face endemic plants when compared to common congeners. Lower SDE may negatively impact reproductive rates and the colonization of new habitats, which may contribute to patterns of endemism.
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Age structure and recruitment of Trillium luteum (Trilliaceae) populations in secondary forests of the southern Appalachian Mountains 1
Article
  • Oct 2019
Members of the genus Trillium are widely distributed in temperate hardwood forests. Due to shared life history traits, including long maturation, self-incompatibility, and limited seed dispersal, the genus is sensitive to anthropogenic disturbance, which reduces plant abundance and fecundity. In the southern Appalachian Mountains, Trillium species are widespread across a range of forest types, but are less common in secondary forests that originated following the abandonment of degraded agricultural land. One exception is Trillium luteum, which commonly occurs in floodplains formerly used as homesteads and farmland. We examined five populations of T. luteum in Great Smoky Mountains National Park to quantify population characteristics of this common, but rarely studied, species and relate these characteristics to historic disturbance. Plants within our sampled populations ranged in minimum age from 2 to 24 yr, with an overall mean age of 9.5 ± 0.4 yr. However, many plants may have been much older than our estimates due to rotting of the rhizome tip. We observed generally continuous recruitment across sites, but some sites displayed distinctly fewer young plants. Neither mean T. luteum density (plants 100 m–2) by life stage nor mean plant age were correlated with overstory density or stand age (P > 0.102). We found that 20% of single-leaf plants originated from sprouts on fragments of old rhizomes. This ability to reproduce vegetatively has been observed in other sessile Trillium species and may provide a reproductive advantage in floodplains and former agricultural lands exposed to regular substrate disturbance.
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Trillium – toward Sustainable Utilization of a Biologically Distinct Genus Valued for Traditional Medicine
Article
  • May 2019
  • BOT REV
Trillium has fascinated the botanical world with its peculiar biology and high medicinal value. The genus appears in North America and Asia, and is widely used for traditional medicine on both continents. Medicinal value has been validated recently through the isolation and ex situ testing of constituent compounds. This study reviews biology, medicinal value, ecological threats and knowledge gaps, and offers suggestions for conservation and sustainable utilization. Findings indicate that the biology of the genus is well explored and the reproductive constraints are well recognized. Steroidal compounds and pharmaceutical potential of the genus are reported, but controlled clinical trials on humans are yet to be conducted. High medicinal value and the peculiar biology have made the genus susceptible to several threats.
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A New Species of Trillium (Melanthiaceae) from Central Georgia and its Phylogenetic Position in Subgenus Sessilium
Article
  • Feb 2019
Analysis of molecular phylogenetic data was used to reveal the existence of a novel species of Trillium subgen. Sessilium. Trillium delicatum sp. nov. differs from the two other low-growing species of the subgenus, T. decumbens and T. reliquum, in features such as straight stems and dung-scented flowers. It occurs in wet floodplain forests in the Oconee and Ocmulgee river drainages in central Georgia, and has a distinct floral scent compared to the wide spectrum in Trillium. The molecular phylogenetic results based on four markers (nuclear ribosomal ITS and plastid trnH-psbA, trnL-trnF, and rpl32-trnL spacers) included samples of all species of the subgenus, and documented the distinctiveness of T. delicatum as a distinct taxon and also provided resolution of species relationships that suggested that the subgenus originated in southeastern North America with two migrations to western North America. The molecular results also suggested the need for closer examination of T. cuneatum and T. lancifolium, and also to assess whether T. decipiens and T. underwoodii are distinct species. Based on the few known populations and susceptibility to damage by hogs, Trillium delicatum is a rare species requiring protection.
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North American Crop Wild Relatives, Volume 1 Conservation Strategies: Conservation Strategies
Book
  • Jan 2018
The plant species that humans rely upon have an extended family of wild counterparts that are an important source of genetic diversity used to breed productive crops. These wild and weedy cousins are valuable as a resource for adapting our food, forage, industrial and other crops to climate change. Many wild plant species are also directly used, especially for revegetation, and as medicinal and ornamental plants. North America is rich in these wild plant genetic resources. This book is a valuable reference that describes the important crop wild relatives and wild utilized species found in Canada, the United States and Mexico. The book highlights efforts taken by these countries to conserve and use wild resources and provides essential information on best practices for collecting and conserving them. Numerous maps using up-to-date information and methods illustrate the distribution of important species, and supplement detailed description on the potential value these resources have to agriculture, as well as their conservation statuses and needs. There is broad recognition of the urgent need to conserve plant diversity; however, a small fraction of wild species is distinguished by their potential to support agricultural production. Many of these species are common, even weedy, and are easily overshadowed by rare or endangered plants. Nevertheless, because of their genetic proximity to agriculturally important crops or direct use, they deserve to be recognized, celebrated, conserved, and made available to support food and agricultural security. This comprehensive two-volume reference will be valuable for students and scientists interested in economic botany, and for practitioners at all levels tasked with conserving plant biodiversity. The chapters 'Public Education and Outreach Opportunities for Crop Wild Relatives in North America' and 'Genetic Resources of Crop Wild Relatives – A Canadian Perspective' are open access under a CC BY 4.0 license via link.springer.com.
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