Literature on distributions, habitat characteristics, and identification of Opuntia species in th... more Literature on distributions, habitat characteristics, and identification of Opuntia species in the southeastern US is scant. Regional treatments of Opuntia are often ambiguous, limited studies based primarily on herbarium specimens. The present work provides a detailed description of the opuntias found in Mississippi along with their distributions and habitat descriptions. Observations, collections, and measurements were made from natural populations within Mississippi and other parts of the southeastern United States. Plants of all taxa were greenhouse grown for approximately two years to monitor morphological characteristics, which sometimes can be quite plastic. Our two-year study encompassed nearly 150 natural populations among several eastern states. Five species are recognized. Of these, Opuntia cespitosa, O. humifusa, and O. pusilla are the most common in Mississippi. O. aff allairei and O. stricta are found infrequently.
Opuntia species have been poorly studied ecologically and taxonomically in the eastern United Sta... more Opuntia species have been poorly studied ecologically and taxonomically in the eastern United States. This study deals with the ecology of Opuntia species in the midsouth United States and covers not only the high degree of morphological variation exhibited by taxa, but also the taxonomy and distributions of the group for Mississippi.
Geranium molle and Erodium cicutarium are reported here as new to the fl ora of Mississippi. Othe... more Geranium molle and Erodium cicutarium are reported here as new to the fl ora of Mississippi. Other collections representing new county records and disjunct populations also are reported. Several of these species are either rare or introduced, which make these fi ndings signifi cant for the Mississippi fl ora.
A floristic survey of Lauderdale County, Mississippi was undertaken from the spring of 2004 throu... more A floristic survey of Lauderdale County, Mississippi was undertaken from the spring of 2004 through the fall of 2009 in order to document the flora and describe plant communities from this poorly studied region within Mississippi. A total of 1175 vascular plant species (1206 taxa altogether, including species and infraspecific taxa) was recorded from the county. Oenothera sinuosa and Geranium molle were collected for the first time in the state of Mississippi, and Carex breviculmis was recorded from North America for the first time. One hundred and eighty-six introduced species were recorded in the county. Forty-seven rare and uncommon species, according to the Mississippi Natural Heritage Program special plant tracking and watch lists, were recorded from Lauderdale County and many range extensions and species disjunctions were discovered. We describe nine primary plant communities in the county and discuss the biogeographical importance of the flora of Lauderdale County relative to the rest of the state.
Literature on distributions, habitat characteristics, and identification of Opuntia species in th... more Literature on distributions, habitat characteristics, and identification of Opuntia species in the southeastern US is scant. Regional treatments of Opuntia are often ambiguous, limited studies based primarily on herbarium specimens. The present work provides a detailed description of the opuntias found in Mississippi along with their distributions and habitat descriptions. Observations, collections, and measurements were made from natural populations within Mississippi and other parts of the southeastern United States. Plants of all taxa were greenhouse grown for approximately two years to monitor morphological characteristics, which sometimes can be quite plastic. Our two-year study encompassed nearly 150 natural populations among several eastern states. Five species are recognized. Of these, Opuntia cespitosa, O. humifusa, and O. pusilla are the most common in Mississippi. O. aff allairei and O. stricta are found infrequently.
Opuntia fragilis, O. humifusa s.l., and O. macrorhiza s.l. are widely distributed prickly pear ta... more Opuntia fragilis, O. humifusa s.l., and O. macrorhiza s.l. are widely distributed prickly pear taxa that have been studied cytologically mostly in western North America, but upper Midwestern United States populations, which form most of the northeastern-most extent of their distributions, have not been analyzed previously. The wide-ranging and most northern of all cacti, O. fragilis, is relatively abundant, at least historically, in the upper Midwestern United States but does not occur further southeast than Jo Daviess County, Illinois, while O. humifusa s.l. is found throughout most of the eastern United States. This difference in distribution may indicate that environmental variables impede the establishment of O. fragilis in most of the eastern United States. We present the first chromosome counts of O. fragilis, O. humifusa s.l., and O. macrorhiza s.l. for 40 populations over part of their Midwestern range and employ habitat niche modeling using 19 environmental variables to extrapolate potential reasons why O. fragilis may not be found in the eastern United States.All twelve populations of O. fragilis analyzed were hexaploid, a finding consistent with previous reports, and adding further evidence for its vegetative dispersal from the southwestern United States, where the species likely originated. Populations of O. humifusa s.l. and O. macrorhiza s.l. were all tetraploid, indicating that the northeastern-most range of those taxa is occupied by polyploid derivatives of their southern diploid relatives. Results from niche modeling suggest suitable habitat for O. fragilis in the upper Midwest is strongly predicted for areas with seasonal fluctuations in temperature but annual precipitation homogeneity, variables that may present significant environmental barriers to the existence of the species in the eastern United States. resumen: Tres taxa de nopales ampliamente distribuidos por los EE. UU., Opuntia fragilis, O. humifusa, y O. macrorhiza han sido estudiados citológicamente en partes de sus distribuciones, pero las poblaciones del medio oeste que forman las distribuciones más al noreste de estas especies, nunca han sido analizadas. O. fragilis, el cactus con un amplio rango de distribución y que se encuentra más al norte que cualquier otra cactácea, es relativamente abundante en el medio oeste de los EE. UU., pero no se encuentra más al sureste del condado Jo Davies en el estado de Illinois; mientras que O. humifusa s.l. se encuentra prácticamente por todo el este de los EE. UU. Factores ambientales podrían estar previniendo el establecimiento de O. fragilis en el este de los EE. UU. Presentamos los primeros recuentos de cromosomas de poblaciones de O. fragilis, O. humifusa s.l., y O. macrorhiza s.l., colectadas en partes de sus rangos de distribución en el medio oeste, y usamos modelaje de nichos de hábitat integrando diecinueve variables ambientales para extrapolar las posibles razones por las cuales O. fragilis esta ausente del este de los EE. UU. Todas las poblaciones de O. fragilis analizadas fueron hexaploides, lo cual concuerda con otros reportes de la especie, y añade evidencia sobre su dispersión vegetativa de su sitio de origen probable, el suroeste de los EE. UU. Todas las poblaciones de O. humifusa s.l. y O. macrorhiza s.l. fueron tetraploides, lo cual indica que la parte noreste de sus rangos de distribución está habitada por derivativas poliploides de sus parientes diploides del sur de los EE. UU. Los resultados del modelaje de nichos de hábitat de O. fragilis sugiere que se puede predecir áreas habitables para O. fragilis por cambios estacionales de la temperatura y homogeneidad de precipitación anual, variables que no se encuentran en el este de los EE. UU., y que pueden ser una barrera para el establecimiento de O. fragilis en esa región.
Citation: Majure LC, Judd WS, Soltis PS, Soltis DE (2012) Cytogeography of the Humifusa clade of ... more Citation: Majure LC, Judd WS, Soltis PS, Soltis DE (2012) Cytogeography of the Humifusa clade of Opuntia s.s. Mill. 1754 (Cactaceae, Opuntioideae, Opuntieae): correlations with pleistocene refugia and morphological traits in a polyploid complex. Comparative Cytogenetics 6(1): 53-77.
Journal of the Botanical Research Institute of Texas, Dec 1, 2014
A new section, Miconia sect. Miconiastrum, is recognized (and includes species previously placed ... more A new section, Miconia sect. Miconiastrum, is recognized (and includes species previously placed in Calycogonium, Charianthus, Miconia, and Tetrazygia). Within this clade, the species of the Miconia bicolor complex are revised. For the nine species of the M. bicolor complex, descriptions, nomenclatural information (including four new names: Miconia karsticola, M. guajaibonensis, M. cajalbanensis, and M. maestrensis), specimen citations, and eco-geographical characterizations are presented, along with an identification key to members of the section. Miconia sect. Miconiastrum represents a monophyletic group within the Caribbean clade of tribe Miconieae (Melastomataceae) and the group is restricted to southern Florida, the Bahamas, Cuba, and Hispaniola. The clade is characterized by hypanthia strongly constricted in fruit, more or less reduced calyx teeth, obovate to spathulate petals, stamens dropping before the petals abscise, and leaves with globularstellate to stellate hairs or peltate scales on the abaxial surface. Most species possess mite domatia formed from a dense tuft of elongate, multicellular, barbate, eglandular hairs in the axils of the midvein and major secondary veins, and they have seeds with smooth to slightly bulging testa cells. Within sect. Miconiastrum a large subclade, i.e., the M. bicolor complex, is diagnosed by 5-or less commonly 6-merous flowers with the petals abaxially papillose-granulose. All members of this clade, except for M. karsticola, also possess paniculate-cymose inflorescences of numerous flowers and abaxial leaf surfaces usually densely covered with well-developed stellate hairs or peltate scales. Within the M. bicolor complex, indumentum characters (as observed on the abaxial leaf surface), form of the calyx tube, size of the calyx lobes, and presence/absence of mite domatia are taxonomically significant.
A high proportion of plant species is predicted to be threatened with extinction in the near futu... more A high proportion of plant species is predicted to be threatened with extinction in the near future. However, the threat status of only a small number has been evaluated compared with key animal groups, rendering the magnitude and nature of the risks plants face unclear. Here we report the results of a global species assessment for the largest plant taxon evaluated to date under the International Union for Conservation of Nature (IUCN) Red List Categories and Criteria, the iconic Cactaceae (cacti). We show that cacti are among the most threatened taxonomic groups assessed to date, with 31% of the 1,478 evaluated species threatened, demonstrating the high anthropogenic pressures on biodiversity in arid lands. The distribution of threatened species and the predominant threatening processes and drivers are different to those described for other taxa. The most significant threat processes comprise land conversion to agriculture and aquaculture, collection as biological resources, and residential and commercial development. The dominant drivers of extinction risk are the unscrupulous collection of live plants and seeds for horticultural trade and private ornamental collections, smallholder livestock ranching and smallholder annual agriculture. Our findings demonstrate that global species assessments are readily achievable for major groups of plants with relatively moderate resources, and highlight different conservation priorities and actions to those derived from species assessments of key animal groups.
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected].
Literature on distributions, habitat characteristics, and identification of Opuntia species in th... more Literature on distributions, habitat characteristics, and identification of Opuntia species in the southeastern US is scant. Regional treatments of Opuntia are often ambiguous, limited studies based primarily on herbarium specimens. The present work provides a detailed description of the opuntias found in Mississippi along with their distributions and habitat descriptions. Observations, collections, and measurements were made from natural populations within Mississippi and other parts of the southeastern United States. Plants of all taxa were greenhouse grown for approximately two years to monitor morphological characteristics, which sometimes can be quite plastic. Our two-year study encompassed nearly 150 natural populations among several eastern states. Five species are recognized. Of these, Opuntia cespitosa, O. humifusa, and O. pusilla are the most common in Mississippi. O. aff allairei and O. stricta are found infrequently.
Opuntia species have been poorly studied ecologically and taxonomically in the eastern United Sta... more Opuntia species have been poorly studied ecologically and taxonomically in the eastern United States. This study deals with the ecology of Opuntia species in the midsouth United States and covers not only the high degree of morphological variation exhibited by taxa, but also the taxonomy and distributions of the group for Mississippi.
Geranium molle and Erodium cicutarium are reported here as new to the fl ora of Mississippi. Othe... more Geranium molle and Erodium cicutarium are reported here as new to the fl ora of Mississippi. Other collections representing new county records and disjunct populations also are reported. Several of these species are either rare or introduced, which make these fi ndings signifi cant for the Mississippi fl ora.
A floristic survey of Lauderdale County, Mississippi was undertaken from the spring of 2004 throu... more A floristic survey of Lauderdale County, Mississippi was undertaken from the spring of 2004 through the fall of 2009 in order to document the flora and describe plant communities from this poorly studied region within Mississippi. A total of 1175 vascular plant species (1206 taxa altogether, including species and infraspecific taxa) was recorded from the county. Oenothera sinuosa and Geranium molle were collected for the first time in the state of Mississippi, and Carex breviculmis was recorded from North America for the first time. One hundred and eighty-six introduced species were recorded in the county. Forty-seven rare and uncommon species, according to the Mississippi Natural Heritage Program special plant tracking and watch lists, were recorded from Lauderdale County and many range extensions and species disjunctions were discovered. We describe nine primary plant communities in the county and discuss the biogeographical importance of the flora of Lauderdale County relative to the rest of the state.
Literature on distributions, habitat characteristics, and identification of Opuntia species in th... more Literature on distributions, habitat characteristics, and identification of Opuntia species in the southeastern US is scant. Regional treatments of Opuntia are often ambiguous, limited studies based primarily on herbarium specimens. The present work provides a detailed description of the opuntias found in Mississippi along with their distributions and habitat descriptions. Observations, collections, and measurements were made from natural populations within Mississippi and other parts of the southeastern United States. Plants of all taxa were greenhouse grown for approximately two years to monitor morphological characteristics, which sometimes can be quite plastic. Our two-year study encompassed nearly 150 natural populations among several eastern states. Five species are recognized. Of these, Opuntia cespitosa, O. humifusa, and O. pusilla are the most common in Mississippi. O. aff allairei and O. stricta are found infrequently.
Opuntia fragilis, O. humifusa s.l., and O. macrorhiza s.l. are widely distributed prickly pear ta... more Opuntia fragilis, O. humifusa s.l., and O. macrorhiza s.l. are widely distributed prickly pear taxa that have been studied cytologically mostly in western North America, but upper Midwestern United States populations, which form most of the northeastern-most extent of their distributions, have not been analyzed previously. The wide-ranging and most northern of all cacti, O. fragilis, is relatively abundant, at least historically, in the upper Midwestern United States but does not occur further southeast than Jo Daviess County, Illinois, while O. humifusa s.l. is found throughout most of the eastern United States. This difference in distribution may indicate that environmental variables impede the establishment of O. fragilis in most of the eastern United States. We present the first chromosome counts of O. fragilis, O. humifusa s.l., and O. macrorhiza s.l. for 40 populations over part of their Midwestern range and employ habitat niche modeling using 19 environmental variables to extrapolate potential reasons why O. fragilis may not be found in the eastern United States.All twelve populations of O. fragilis analyzed were hexaploid, a finding consistent with previous reports, and adding further evidence for its vegetative dispersal from the southwestern United States, where the species likely originated. Populations of O. humifusa s.l. and O. macrorhiza s.l. were all tetraploid, indicating that the northeastern-most range of those taxa is occupied by polyploid derivatives of their southern diploid relatives. Results from niche modeling suggest suitable habitat for O. fragilis in the upper Midwest is strongly predicted for areas with seasonal fluctuations in temperature but annual precipitation homogeneity, variables that may present significant environmental barriers to the existence of the species in the eastern United States. resumen: Tres taxa de nopales ampliamente distribuidos por los EE. UU., Opuntia fragilis, O. humifusa, y O. macrorhiza han sido estudiados citológicamente en partes de sus distribuciones, pero las poblaciones del medio oeste que forman las distribuciones más al noreste de estas especies, nunca han sido analizadas. O. fragilis, el cactus con un amplio rango de distribución y que se encuentra más al norte que cualquier otra cactácea, es relativamente abundante en el medio oeste de los EE. UU., pero no se encuentra más al sureste del condado Jo Davies en el estado de Illinois; mientras que O. humifusa s.l. se encuentra prácticamente por todo el este de los EE. UU. Factores ambientales podrían estar previniendo el establecimiento de O. fragilis en el este de los EE. UU. Presentamos los primeros recuentos de cromosomas de poblaciones de O. fragilis, O. humifusa s.l., y O. macrorhiza s.l., colectadas en partes de sus rangos de distribución en el medio oeste, y usamos modelaje de nichos de hábitat integrando diecinueve variables ambientales para extrapolar las posibles razones por las cuales O. fragilis esta ausente del este de los EE. UU. Todas las poblaciones de O. fragilis analizadas fueron hexaploides, lo cual concuerda con otros reportes de la especie, y añade evidencia sobre su dispersión vegetativa de su sitio de origen probable, el suroeste de los EE. UU. Todas las poblaciones de O. humifusa s.l. y O. macrorhiza s.l. fueron tetraploides, lo cual indica que la parte noreste de sus rangos de distribución está habitada por derivativas poliploides de sus parientes diploides del sur de los EE. UU. Los resultados del modelaje de nichos de hábitat de O. fragilis sugiere que se puede predecir áreas habitables para O. fragilis por cambios estacionales de la temperatura y homogeneidad de precipitación anual, variables que no se encuentran en el este de los EE. UU., y que pueden ser una barrera para el establecimiento de O. fragilis en esa región.
Citation: Majure LC, Judd WS, Soltis PS, Soltis DE (2012) Cytogeography of the Humifusa clade of ... more Citation: Majure LC, Judd WS, Soltis PS, Soltis DE (2012) Cytogeography of the Humifusa clade of Opuntia s.s. Mill. 1754 (Cactaceae, Opuntioideae, Opuntieae): correlations with pleistocene refugia and morphological traits in a polyploid complex. Comparative Cytogenetics 6(1): 53-77.
Journal of the Botanical Research Institute of Texas, Dec 1, 2014
A new section, Miconia sect. Miconiastrum, is recognized (and includes species previously placed ... more A new section, Miconia sect. Miconiastrum, is recognized (and includes species previously placed in Calycogonium, Charianthus, Miconia, and Tetrazygia). Within this clade, the species of the Miconia bicolor complex are revised. For the nine species of the M. bicolor complex, descriptions, nomenclatural information (including four new names: Miconia karsticola, M. guajaibonensis, M. cajalbanensis, and M. maestrensis), specimen citations, and eco-geographical characterizations are presented, along with an identification key to members of the section. Miconia sect. Miconiastrum represents a monophyletic group within the Caribbean clade of tribe Miconieae (Melastomataceae) and the group is restricted to southern Florida, the Bahamas, Cuba, and Hispaniola. The clade is characterized by hypanthia strongly constricted in fruit, more or less reduced calyx teeth, obovate to spathulate petals, stamens dropping before the petals abscise, and leaves with globularstellate to stellate hairs or peltate scales on the abaxial surface. Most species possess mite domatia formed from a dense tuft of elongate, multicellular, barbate, eglandular hairs in the axils of the midvein and major secondary veins, and they have seeds with smooth to slightly bulging testa cells. Within sect. Miconiastrum a large subclade, i.e., the M. bicolor complex, is diagnosed by 5-or less commonly 6-merous flowers with the petals abaxially papillose-granulose. All members of this clade, except for M. karsticola, also possess paniculate-cymose inflorescences of numerous flowers and abaxial leaf surfaces usually densely covered with well-developed stellate hairs or peltate scales. Within the M. bicolor complex, indumentum characters (as observed on the abaxial leaf surface), form of the calyx tube, size of the calyx lobes, and presence/absence of mite domatia are taxonomically significant.
A high proportion of plant species is predicted to be threatened with extinction in the near futu... more A high proportion of plant species is predicted to be threatened with extinction in the near future. However, the threat status of only a small number has been evaluated compared with key animal groups, rendering the magnitude and nature of the risks plants face unclear. Here we report the results of a global species assessment for the largest plant taxon evaluated to date under the International Union for Conservation of Nature (IUCN) Red List Categories and Criteria, the iconic Cactaceae (cacti). We show that cacti are among the most threatened taxonomic groups assessed to date, with 31% of the 1,478 evaluated species threatened, demonstrating the high anthropogenic pressures on biodiversity in arid lands. The distribution of threatened species and the predominant threatening processes and drivers are different to those described for other taxa. The most significant threat processes comprise land conversion to agriculture and aquaculture, collection as biological resources, and residential and commercial development. The dominant drivers of extinction risk are the unscrupulous collection of live plants and seeds for horticultural trade and private ornamental collections, smallholder livestock ranching and smallholder annual agriculture. Our findings demonstrate that global species assessments are readily achievable for major groups of plants with relatively moderate resources, and highlight different conservation priorities and actions to those derived from species assessments of key animal groups.
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected].
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Papers by Lucas Majure