Ladd, D. and J.R. Thomas. 2015. Ecological checklist of the Missouri flora for Floristic Quality Assessment. Phytoneuron 2015-12: 1–274. Published 12 February 2015. ISSN 2153 733X ECOLOGICAL CHECKLIST OF THE MISSOURI FLORA FOR FLORISTIC QUALITY ASSESSMENT DOUGLAS LADD The Nature Conservancy 2800 S. Brentwood Blvd. St. Louis, Missouri 63144 [email protected] JUSTIN R. THOMAS Institute of Botanical Training, LLC 111 County Road 3260 Salem, Missouri 65560 [email protected] ABSTRACT An annotated checklist of the 2,961 vascular taxa comprising the flora of Missouri is presented, with conservatism rankings for Floristic Quality Assessment. The list also provides standardized acronyms for each taxon and information on nativity, physiognomy, and wetness ratings. Annotated comments for selected taxa provide taxonomic, floristic, and ecological information, particularly for taxa not recognized in recent treatments of the Missouri flora. Synonymy crosswalks are provided for three references commonly used in Missouri. A discussion of the concept and application of Floristic Quality Assessment is presented. To accurately reflect ecological and taxonomic relationships, new combinations are validated for two distinct taxa, Dichanthelium ashei and D. werneri , and problems in application of infraspecific taxon names within Quercus shumardii are clarified. CONTENTS Introduction Species conservatism and floristic quality Application of Floristic Quality Assessment Checklist: Rationale and methods Nomenclature and taxonomic concepts Synonymy Acronyms Physiognomy, nativity, and wetness Summary of the Missouri flora Conclusion Annotated comments for checklist taxa Acknowledgements Literature Cited Ecological checklist of the Missouri flora Table 1. C values, physiognomy, and common names Table 2. Synonymy crosswalk Table 3. Wetness ratings and plant families INTRODUCTION This list was developed as part of a revised and expanded system for Floristic Quality Assessment (FQA) in Missouri. FQA is a method of assessing the natural integrity and recovery potential of an area based on vegetation, and tracking management response through time (Taft et al. 1997). Ladd and Thomas: Ecological checklist of the Missouri flora 2 Key to deployment of a Floristic Quality Assessment system is a disciplined enumeration of the vascular flora of a region, with a standardized convention for names and acronyms for each taxon. Other attributes for each taxon include whether it is introduced or native to a region, life history traits (physiognomy), degree of predilection for wetland conditions, and a conservatism ranking (C value). The conservatism ranking is an integer between 0 and 10 reflecting the degree of obligate dependence of a taxon on intact natural habitats with direct composition, site conditions, and process regime linkage to the immediate pre-Eurosettlement period. For each taxon, coefficients are assigned based on observed ecological performance, derived from collective extended field experience and empirical observations in the contemporary landscape. Factors influencing C value include disturbance tolerance, habitat affinities, and degree of dependence on intact native vegetation assemblages and their associated site conditions and process regimes. The concept of species conservatism and Floristic Quality Assessment was first developed by Wilhelm (1977), who applied it at a county level. The system was subsequently modified and expanded by Wilhelm and Ladd (1988). The first FQA system for Missouri was developed by the senior author in 1987 and refined in 1993 (Ladd 1993); this was the first application of FQA at a statewide scale. Since then, FQA systems have been developed for multiple states and provinces (e.g. Herman et al. 1997; Oldham et al. 1995; Rocchio et al. 2013). SPECIES CONSERVATISM AND FLORISTIC QUALITY In the New World, native biological systems and their component biota are under intensifying levels of stress. In midcontinental North America, since the peak of the last glacial advance some 15,000 years ago, these systems had persisted for millennia in dynamically stable arrays, supporting an unimaginable diversity of organisms with complex interactions. Today, unprecedented levels of habitat destruction and altered process regimes, such as fire and grazing, have resulted in fragmented, largely degraded systems with reduced ecological function, resiliency, and diversity. These impacts have been exacerbated by the biologically new prevalence of a suite of introduced organisms adapted to the perturbations our sedentary urban/intensive agriculture society has imposed on the landscape. Native species respond differently to perturbations that are novel to or exceed the magnitude and/or frequency of the post-glacial regimes to which they were attuned. Some species are more facultative and adaptable and can tolerate significant impacts, sometimes even increasing opportunistically in response to post-Eurosettlement disturbances. Other taxa are obligately restricted to the site conditions, associations, and constrained range of process regimes and conditions that characterized the post-glacial, pre-Eurosettlement landscape. If process regimes are altered and degrading impacts occur, these species are typically the least capable of maintaining their viability and are lost from the system. These taxa, once locally expunged from a site, are also least capable of becoming reestablished in the contemporary landscape, resulting in losses of aggregate biodiversity. These losses can further destabilize the system, resulting in cascading effects of further degradation, increasing loss of native biodiversity, and increased vulnerability to invasive species and their deleterious impacts. This pattern of organismal performance in the landscape reveals two key issues. First, certain organisms are fundamentally linked, spatially and temporally, to pre-Eurosettlement incarnations of ecosystems and are vulnerable to loss from disturbances and perturbations. To the extent that human society considers it a priority to maintain functional, viable examples of natural systems, direct efforts are required to sustain these systems and the most sensitive components of their biota. Secondly, this conceptual spectrum of organismal response to system perturbation and degradation can be used to assess and monitor the degree to which the contemporary environment and human activities are maintaining or degrading system integrity and diversity, particularly among those organisms least able to become reestablished once lost from the system. Ladd and Thomas: Ecological checklist of the Missouri flora 3 This obligate reliance on intact native systems and process regimes prevailing prior to Eurosettlement is called species conservatism . Conservatism embodies two interrelated tenants: (1) organisms differ in their tolerance of and response to disturbance, and (2) organisms display varying degrees of fidelity to intact habitats, process regimes, and site continuity. Conservatism can be can be codified along a continuum ranging from species obligately restricted to intact natural systems and process regimes ― highly conservative species ― to species whose presence is completely uncorrelated, or even negatively correlated, with these factors ― non-conservative species. Non- native taxa, because they have no role in native systems, cannot have conservatism and are conceptually excluded. Organismal performance along this spectrum of species conservatism can be numerically ranked and used to assess overall system condition and performance through time. Assigning an integer value to each taxon of the vascular vegetation, ranging from 0 for species with no inherent conservatism to 10 for species that are fundamentally conservative, results in a valuable tool for gleaning insights into our landscape. Through careful, disciplined assessment of the observed performance of each species in the contemporary environment, these valuations can be assigned by experienced, botanically astute field biologists with a good sense of local ecosystems. The collective response of the components of the vegetation can then be used to derive meaningful information regarding the degree to which the system is maintaining itself, particularly its least replaceable components, through time. As an example, in Missouri Common Ragweed, Ambrosia artemisiifolia , although a native plant that can occur in our finest natural areas (albeit in low numbers), occurs in virtually any habitat, including newly cleared land and highly disturbed environments. This fundamental lack of conservatism results in a conservatism ranking (C value) of 0. At the other end of the spectrum, Epiphytic Sedge, Carex decomposita , is restricted to high quality sinkhole ponds with intact hydrological regimes and a consistent suite of obligate wetland associates; once the species and its seedbank are lost from a pond, it is unlikely to become reestablished. This obligate fidelity to intact systems with direct linkage to pre-Eurosettlement site conditions and processes results in a C value of 10. Within this spectrum, every taxon in the vegetation can be assigned a numerical rating based solely on its observed ecological performance, but exclusive of perceptions of rarity, jurisdictional protection, endangered status, appearance, utility to humans or wildlife, toxicity, or other extraneous factors. In essence, the mind-boggling complexity of the responses of the more than 2000 taxa of native plants comprising our local systems is distilled