Phyla nodiflora (L.) Greene

https://thekeep.eiu.edu/herbarium_specimens_byname/19062/thumbnail.jp

Aloysia gratissima (Gillies & Hook.) Troncoso

https://thekeep.eiu.edu/herbarium_specimens_byname/18932/thumbnail.jp

Verbena officinalis L.

https://thekeep.eiu.edu/herbarium_specimens_byname/19311/thumbnail.jp

Forestiera angustifolia Torr.

https://thekeep.eiu.edu/herbarium_specimens_byname/21084/thumbnail.jp

Kinematically Extended Continuum Theories: Correlation Between Microscopical Deformation and Macroscopical Strain Measures

The present work investigates the correlation between macrocscopical deformation modes and microscopical deformation modes. Thereby, the macroscopical deformation is represented by the strain-like quantities of the according macroscopical continuum theory while the microscopical deformation is expressed in the form of a Taylor series expansion. The use of an energy criterion makes it possible to derive a quantitative relation between microscopical and macroscopical deformation. The procedure is applied to different kinematically extended continuum theories on the macroscopical level. The investigation may help to select an optimal macroscopical continuum theory instead of choosing a theory based on phenomenological observations, whereby the optimal theory ist that one, which reflects the microscopical deformation behaviour best. The microscopical deformation behaviour depends on the topology of the microstructure under consideration. Thus, the optimal theory is affected by the topology of the microstructure

Bumelia lanuginosa Pers.

https://thekeep.eiu.edu/herbarium_specimens_byname/21531/thumbnail.jp

Multigenetic origin of the X-discontinuity below continents: insights from African receiver functions

Constraints on chemical heterogeneities in the upper mantle may be derived from studying the seismically observable impedance contrasts that they produce. Away from subduction zones, several causal mechanisms are possible to explain the intermittently observed X-discontinuity (X) at 230–350 km depth: the coesite-stishovite phase transition, the enstatite to clinoenstatite phase transition, and/or carbonated silicate melting, all requiring a local enrichment of basalt. Africa hosts a broad range of terranes, from Precambrian cores to Cenozoic hotspots with or without lowermost mantle origins. With the absence of subduction below the margins of the African plate for >0.5 Ga, Africa presents an ideal study locale to explore the origins of the X. Traditional receiver function (RF) approaches used to map seismic discontinuities, such as common conversion-point stacking, ignore slowness information crucial for discriminating converted upper mantle phases from surface multiples. By manually assessing depth and slowness stacks for 1° radius overlapping bins, normalized vote mapping of RF stacks is used to robustly assess the spatial distribution of converted upper mantle phases. The X is mapped beneath Africa at 233–340 km depth, revealing patches of heterogeneity proximal to mantle upwellings in Afar, Canaries, Cape Verde, East Africa, Hoggar, and Réunion with further observations beneath Cameroon, Madagascar, and Morocco. There is a lack of an X beneath southern Africa and strikingly, the magmatic eastern rift branch of the southern East African Rift. With no relationships existing between depth and amplitudes of observed X and estimated mantle temperatures, multiple causal mechanisms are required across a range of continental geodynamic settings

Bumelia celastrina Kunth

https://thekeep.eiu.edu/herbarium_specimens_byname/21527/thumbnail.jp

Forestiera pubescens Nutt.

https://thekeep.eiu.edu/herbarium_specimens_byname/21086/thumbnail.jp

A Systematic Treatment of Acacia coulteri (Fabaceae, Mimosoideae) and Similar Species in the New World

Detailed descriptions, habitat preferences, geographic ranges, and representative specimens are given for the 13 taxa of the Acacia coulteri group from Mexico, Central America, and the southwestern United States. These species form a distinct group within Acacia series Vulgares, lacking prickles and usually having persistent stipules. A principal components analysis (PCA) of vegetative and floral features shows that the specimens examined form discrete units in plots of the first three principal components. The groups established by PCA mostly coincide with previously described species. The taxa within this group are phenetically similar, sharing many morphological features. These data also suggest that there is occasional gene flow between species, but that hybrids are not common. About half the species have restricted ranges (A. compacta, A. dolichostachya, A. durangensis, A. millefolia, A. russelliana, A. sericea, and A. willardiana), but the remainder are wide-ranging, either from Oaxaca and Puebla north into central and northern Mexico (A. acatlensis, A. coulteri, A. mammifera, and A. salazari), or south into Central America (A. centralis and A. usumacintensis)