Scale and bark injuries (a condition called epidermal browning) have been shown to occur on stem surfaces of 21 species of tall, long-lived cactus species throughout the Americas. The amounts of surface injuries are highly correlated with amounts of sunlight exposures. Epidermal browning causes cactus morbidity and mortality of saguaro cacti. For this study, rates of morbidity and mortality of saguaro cacti (Carnegiea gigantea (Engelm.) Britt and Rose) were determined for 1061 plants from 50 desert field plots. From 2002 to 2010, 16.5% of all saguaros died (increased mortality). During the same period, the percentage of cacti with few epidermal injuries decreased from 25 to 9%, with a 16% increase in initial morbidity. Over this same period, about 10% of the population had a rapid increase of epidermal browning (rapid morbidity). Thus, marked increases in morbidity and mortality occurred over the eight-year period. WEKA, a standard machine-learning program, was used to determine the characteristics of saguaros that predispose them to (1) die, (2) initiate morbidity (start of epidermal browning symptoms) and (3) initiate rapid morbidity (a rapid increase in epidermal browning). Decision trees were created using the C4.5 algorithm, a top-down method that repeatedly chooses the question that produces a maximal information gain. Amounts of epidermal browning on north-facing troughs alone predicted cactus mortality with 89.1% accuracy. Initial morbidity was predicted with 80.2% accuracy with data of south-facing troughs and crests only. Rapid morbidity (less than 20% epidermal browning in 2002 and more than 50% by 2010) was predicted with a very large tree with 79.6% accuracy. For example, rapid morbidity is predicted by more than 3.1% epidermal browning on left troughs on south-facing surfaces in 2002 with 80% accuracy. Moreover, rapid morbidity was also predicted if east-facing crests had more than 3.9% epidermal browning in 2002. Overall, decision tree analysis was very effective at predicting changes in mortality and morbidity for the population of 1061 saguaros from 2002 to 2010. Data from trough surfaces were more effective than data from crests for predicting mortality and morbidity.

Lectotypification for the following names is proposed: Scleria filiculmis Boeckeler, Scleria catharinensis Boeckeler, Scleria microcarpa Nees ex Kunth and Scleria panicoides Kunth. The chosen lectotypes and respective discussions are presented as follow.

Chusquea Kunth and Rhipidocladum McClure species (Poaceae, Bambusoideae, Bambuseae) are the only two genera of woody bamboos whose distributions reach the southernmost portion of the Andes mountain range. The identification of woody bamboos relies mainly on vegetative characters. In the present work, foliage leaf blade anatomy of Andean woody bamboo species occurring in Argentina and neighboring areas is described. Eight species are surveyed: Chusquea culeou E. Desv., C. deficiens Parodi, C. lorentziana Griseb., C. montana Phil., C. quila Kunth, C. valdiviensis Phil., Rhipidocladum neumannii Sulekic, Rúgolo & L. G. Clark and R. racemiflorum (Steud.) McClure. Leaf blade abaxial epidermal and cross section characters of each species are described and an identification key based on anatomical characters is provided. Anatomical evidence that support the idea of C. quila and C. valdiviensis as different species is presented and information on useful characters to distinguish between them is provided. Also, taxonomic position of R. neumannii is determined based on anatomical features. Finally, the taxa studied are compared in tables based on leaf anatomical characters of taxonomic value.

Planting native grasses can provide a source of seed for prairie restorations, but requires knowledge of how the plants that establish will perform. This study sought to determine variation in fitness of population sources of Andropogon gerardii, a dominant grassland species, when grown in a mesic common garden. Using multiple population sources, we tested the hypothesis that plants from populations within the local region would exhibit a ‘home-site advantage’ as measured by higher fitness compared to plants from populations collected from drier regions of the tallgrass prairie ecosystem (up to 986 km west of the common garden). Plants collected from four pristine, never restored population sources from each of three regions (central Kansas, eastern Kansas, and southern Illinois) were raised in the greenhouse from seeds and planted in a common garden in Illinois. To estimate fitness, we used commonly measured traits related to seed production, including flowering tiller number and number of flowering raceme branches, seed number, viability, and percentage germination. There was no evidence of a ‘home-site advantage’ for populations originating from southern Illinois. Rather, there was high within-region variability in fecundity. Plants from southern Illinois had the largest number of raceme branches per plant. Plants from eastern Kansas had the highest number of vegetative tillers per plant. Plants from central Kansas produced the most germinable seeds. Under the current climate, plants from any one of the three regions may be suitable to propagate seeds for restoration, but other traits may vary among populations to affect height, cover, and productivity.

Cipollini, M. L., (Department of Biology, Berry College, PO Box 430, Mount Berry, GA 30149), J. Culberson (2575 Oglethorpe Mountain Road, Jasper, GA 30143), D. Whigham (Plant Ecology Lab, Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, MD 21037), K. Johnson (Department of Biology, Berry College, PO Box 430, Mount Berry, GA 30149), T. Knight (Environmental Studies, St. John's University, New Science Center 116, Collegeville, MN 56321) and J. O'Neill (Plant Ecology Lab, Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, MD 21037). Spatial and temporal patterns of sexual dimorphism and sex ratio in Lindera benzoin L. (Lauraceae). J. Torrey Bot. Soc. 140: 280–299. 2013.—The focus of this study is spatial and temporal variation in sex ratio and sexual dimorphism in the woody dioecious shrub Lindera benzoin (spicebush, Lauraceae). This species has been shown to express female-biased flowering sex ratios in a focal study population in Maryland. Sex ratio variation and sexual dimorphism in dioecious plants has attracted the focus of many short-term, single site studies, particularly in light of Fisher's (1930) elucidation of the selective pressures favoring the production of unbiased progeny sex ratios. As informative as such studies have been, long term, multi-site studies are necessary for full evaluation of the factors leading to differential expression of sex within and among populations. Female-biased sex ratios, relatively rare among plant species, are particularly difficult to explain when many studies, including ours of L. benzoin, show females to have higher costs of reproduction and lower modular growth rates suggesting a competitive disadvantage in comparison with males. This study focuses intensively on a single population in Maryland, and is augmented by flowering censuses, and plant size and growth estimates in populations at 11 nearby sites in Maryland, and four distant sites in Pennsylvania, Virginia and West Virginia. Data were collected at most sites in the early 1990s and again in 2010, so that long-term variation in sex ratio could be explored. Results show tendencies for overall female-bias, for female bias in small size classes and male bias in large size classes, for an increase in the proportion of males within populations over time, and for sex ratios to be biased toward females in relatively recently established populations but unbiased or male-biased in older populations. Sexual dimorphism favoring males was consistent across sites, but no sexual dimorphism in herbivory by mammals or by foliage feeding insects was detected. These field observations combined with data derived from a separate but concurrent garden study suggest that early establishment of female-biased sex ratios may occur via a faster early growth rate and possible better tolerance of herbivory by females. This model further suggests that early advantages of females are followed by post-reproductive demographic changes favoring males, resulting in a tendency for sex ratios to shift toward maleness over time.

The adult genet sex ratio of a wild population of the dioecious woody shrub Lindera benzoin (spicebush) in Maryland has shown a persistent female-bias over a time span of over 17 years. Female-biased sex ratios are relatively rare in dioecious plants, and are not easily explained by costs of reproduction, which are often higher in females. In fact, data from reproductive adults in this population showed modular growth favoring males, which led to questions concerning the source of female-bias. Using seeds collected from 20 maternal plants in 1992, a garden study was conducted from 1993–2003 in which periodic flowering censuses were conducted, and plant size parameters were recorded. The plants were grown in a relatively tightly packed array which likely forced early intraspecific competition. The results suggested that L. benzoin females may compensate for differential costs of reproduction via larger initial seed size and early growth rate, but that sexual dimorphism in such a highly competitive scenario can favor males even more dramatically than in typical field conditions. Despite larger early size and faster growth in female seedlings, males showed clear advantages over females in the post-reproductive period and mortality was much higher in female genets. Sex ratios were close to the same level of female bias seen in the wild population around the time of initial flowering, but trended toward maleness as post-reproductive stage genet mortality ensued. Explanations for the development and persistence of female bias include larger seedling size that may give females a competitive advantage over males in the pre-reproductive stage, which under certain circumstances may lead to greater survival of female seedlings. Variation among habitats in herbivory and other environmental factors that influence survival and sex expression could ameliorate the competitive advantage of males associated with their lower reproductive costs.

A century of dramatically altered disturbance regimes has likely changed patterns of forest regeneration, with potential detrimental consequences for the future diversity, composition, and function of late-succession and old-growth forest stands. We quantified the diversity and composition of tree species in the canopy and understory layers of 19 late-successional and old-growth forest stands in Pennsylvania to evaluate the consequences of existing regeneration patterns for the future composition of these communities. Despite relatively high canopy diversity across all stands, the understory of all stands was comprised of a small homogeneous subset of the canopy species. In addition, understory layers had lower species diversity than their respective canopies and showed a significant lack of species intermediate in shade tolerance. Oak species, which often require fire to regenerate, were common in the canopy of 12 stands, but nearly absent from the understory layer of all stands. Our findings are consistent for late-succession and old-growth stands located across a large geographic area of Pennsylvania and across stands of varying sizes, canopy species composition, and location in different physiographic provinces. These findings suggest that disruptions to historical disturbance and browsing regimes play a strong role in this dramatic homogenization of understory species composition. In the absence of large-scale disturbance, these stands will become relatively depauperate and composed of a homogeneous subset of species that are simultaneously shade-tolerant, browse-tolerant, and fire-intolerant.

A taxonomic review of the species of Vriesea sect. Xiphion with simple inflorescences indicated that a lectotype for Vriesea fenestralis Linden & André was needed because its holotype cannot be found. We have designated the lectotype and provide a list of studied material along with comments on the geographic distribution, taxonomy and conservation of the species.

White-tailed deer (Odocoileus virginianus, Zimmerman 1780) are known to disperse seeds through endozoochory, but the fates of these seeds are largely unknown. In both field and greenhouse studies, we examined the importance of fecal pellet decay to seed germination success and compared natural plant communities in microsites with and without deer pellets to determine the effects of deer endozoochory on short-term plant species composition. Pellets were collected in Delaware County, Ohio. After cold stratification, pellets were either crumbled or planted intact in the greenhouse to estimate numbers and species of viable seed present. These plantings produced germinants of 40 taxa, 48% of which are non-native. Significantly more individuals germinated from crumbled than from intact pellets (P < 0.001), suggesting that pellet decay is crucial for germination success. In the field, feces deposited in the fall and spring decayed at rates that would allow seeds to escape the pellets in time for spring germination. Plant species diversity was also compared between forest microsites containing pellets and adjacent sites without pellets. Late spring plant diversity in pellet plots was similar to that of control sites, suggesting that the presence of deer pellets does not result in short-term compositional changes to the understory plant community. Our data support other studies that have also found deer to be capable of dispersing seeds of many plant species. Our study indicates that pellet decay facilitates germination for many of these species. However, given the similarity of plants found in microsites with and without pellets, seeds dispersed by deer did not become significant components of forest understories over a one year time period. It may be that seeds contained in pellets will enter the seed bank and germinate with a change in environment (such as a gap opening), but further field work must be done to determine the fates of seeds dispersed by deer in forest habitats.

Larrea tridentata is a dominant and widespread shrub of North American warm deserts. The species comprises three “chromosomal races,” including diploids (Chihuahuan Desert), tetraploids (Sonoran Desert), hexaploids (Mojave and western Sonoran Deserts), as well as the geographically restricted tetraploid L. tridentata var. arenaria. Creosote bush is a recent arrival to the North American continent, and it is hypothesized that its geographic dispersion reflects rapid ecological divergence mediated by polyploidization. Here we use species distribution modeling to quantitatively evaluate alternate hypotheses for cytotype distributions, based on comprehensive field sampling of creosote bush populations over four years. Using ecological niche models and analyses of field-collected soils, we test whether (1) the climatic niche of the three cytotypes are differentiated; (2) there is evidence for strong climatic gradients at the distributional boundaries of the cytotypes; and (3) cytotype ranges are distinguished by edaphic features. Quantitative tests of niche equivalence indicated that distribution models for all cytotypes were significantly different from one other, suggesting that cytotype races occupy unique and distinctive habitats. However, tests of niche similarity suggest a pattern of niche conservatism, wherein cytotypes tend to occur in climatically similar regions of their respective deserts. Moreover, the modeled diploid distribution was projected to intrude into the geographic range of tetraploids, and the modeled tetraploid distribution was projected to intrude into the range of hexaploids, suggesting that intercytotype competition is a factor influencing cytotype distributions. The range boundary between the dune endemic L. tridentata var. arenaria and hexaploid L. tridentata was noteworthy for exhibiting a strong climatic gradient and striking differences in soil texture (increased sand, decreased gravel). More generally, soil texture differed statistically between sites occupied by diploid, tetraploid, and hexaploid L. tridentata, albeit with considerable overlap across the geographic ranges of the three cytotypes. Taken together, our findings suggest that multiple factors affect the distribution of creosote bush chromosome races, including but not limited to ecological divergence.

Ice storms can break limbs from the crowns of trees, thereby reducing the photosynthetic capability of damaged trees while increasing the availability of light to neighboring trees. I quantified the effect of damage to canopy trees of red oak (Quercus rubra L.) and white oak (Quercus alba L.) following a 2008 ice storm in Massachusetts. Radial growth decreased with increasing canopy loss, but growth increased with increasing loss of limbs from canopy neighbors. The net effect on growth was usually negative, but was positive even for some heavily damaged trees. The relationship was also linear, suggesting that the categories of damage used in previous studies were not necessary. Susceptibility to ice damage tended to decrease with increasing stem diameter, a trend not seen in previous studies. The results from this and earlier studies show that initial damage and subsequent radial growth are influenced by several factors. To quantify the community and ecosystem effects of ice storms, the complexities of damage and recovery must be taken into account.

Leopoldinia is palm genus with three species, L. major, L. pulchra and Leopoldinia piassaba. The taxonomic status of these three species is supported by vegetative and reproductive morphological evidence. There are some conflicting views of the treatment of two species, L. major and L. pulchra, which some authors consider a single species and others as two separate species. The findings in this study show that L. major and L. pulchra have three distinct anatomical features that support their species status. First, the dorsiventral leaf type of L. pulchra as opposed to the isolateral leaf type of L. major. Second, the epidermis of L. pulchra is formed by fibrous and tannin filled cells while in L. major epidermal cells are thin walled cells. Third, stomata distribution in L. major is amphistomatic and in L. pulchra is hypostomatic. These anatomical features are consistent with the horizontal and pendulous appearance of their respective pinnae.