A new species, Geranium mutisii, from La Guajira in Colombia is described and illustrated.

Three species that occur in montane forests in Eastern Brazil are described here. Behuria capixaba occurs in the state of Espírito Santo and Ossaea loligomorpha in Bahia, while Miconia dorsaliporosa occurs in both states.

Structure and development of included phloem was investigated in the stems of Calycopteris floribunda Lamk., of the Combretaceae. After the definite period of cambial activity, cells in the middle of the cambial zone began to differentiate into thin walled cambial derivatives which separated the cambium into outer and inner cambial segment at certain places. Rest of the cambium along with separated outer segment remained functionally active while inner segment became temporarily nonfunctional. Original circular outline of the cambial cylinder was restored by joining of outer segment with existing one whereas inner cambial segment got embedded resulting in production of an islands of included phloem in the secondary xylem. This process was repeated several times resulting in a number of phloem islands surrounded within thick walled secondary xylem. Differentiation of phloem elements was initiated only after the formation of thick walled xylem derivatives from the outer cambial segment. The segments of the cambium producing the phloem island remained active for fairly long time. Sieve tube elements of the phloem islands situated deep inside the older stem became non-functional and underwent obliteration after heavy accumulation of callose. Secondary xylem was diffuse porous with indistinct growth rings and composed of vessels (both wider and fibriform vessels), nucleated xylem fibers, axial and ray parenchyma. Perforated ray cells were also encountered frequently in all the samples studied. Structure and development of included phloem is described in detail and possible significance of nucleated fibers and perforated ray cells is discussed.

Hummingbirds are important pollinators in Monteverde, Costa Rica, as they are in most neotropical montane cloud forests. In Monteverde, hummingbird-pollinated plants are generally pollen-limited and incapable of autonomous self-pollination. However, many hummingbird-pollinated plants in the Bromeliaceae are capable of autonomous self-pollination. We examined the breeding system and pollination of Pitcairnia brittoniana (Mez), shown previously to be capable of autonomous selfing. We found that fruit and seed set were high in open-, self-, and cross-pollinated treatments, as well as in the autonomous self-pollination treatment. Seed set, but not fruit set was slightly lower among pollinator-excluded flowers from which the anthers or stigma were removed at dawn, the time at which flowers are first receptive to cross-pollination, relative to controls whose anthers and stigmas were unmanipulated. Flowers were visited by two hummingbird species that deposited cumulative cross-pollen loads sufficient for near maximum seed set. Therefore, P. brittoniana has the potential for high levels of either outcrossing or inbreeding in Monteverde. Although the relative competitive abilities of self- and cross-pollen in P. brittoniana are unknown, cross-pollen prepotency is probable. Pitcairnia brittoniana likely maintains a mixed mating system, outcrossing when hummingbirds are active and selfing autonomously when they are scarce.

Spatial patterns of mistletoe seed deposition are behaviorally determined by frugivorous birds but the effects of gut passage on mistletoe seed germination has received little attention. Here we investigate the effects of several predictors and passage through the digestive tube of two bird species, Grey Silky-flycatcher (GSF, Ptilogonys cinereus) and Cedar Waxwings (CW, Bombycilla cedrorum) on seed germination of Psittacanthus schiedeanus (Loranthaceae). Fruits were collected from mistletoe plants growing on three host tree species, Liquidambar styraciflua, Acacia pennatula, and Rapanea myricoides. More mistletoe seeds from Liquidambar trees germinated than those from Acacia and Rapanea trees, regardless of fruit treatment. Fewer seeds defecated by GSFs germinated compared to those defecated by CWs or manually extracted. However, analyzed within a generalized linear modeling framework, host source and seed weight were the best predictors for the occurrence of germination. Seeds were retained longer in the guts of GSFs than seeds in those of CWs, and increased retention time reduced significantly mistletoe seed germination. This study demonstrated that gut passage affected seed germination responses of mistletoes of P. schiedeanus, and additional studies should examine this relationship for other mistletoe-bird interactions.

Fleshy-fruited plants are an important component of the invasive flora of the northeastern United States, but few studies have examined how avian frugivory may benefit such plants. European starlings (Sturnus vulgaris) are one of the most abundant avian frugivores in New England, and if effective seed dispersers for fleshy-fruited invasive plants, starlings may participate in a mutualistic interaction which benefits both the invasive plants and birds involved. Here, we investigate the role of European starlings in facilitating the germination of three invasive, fleshy-fruited plants with which they co-occur: Elaeagnus umbellata, Celastrus orbiculatus, and Rosa multiflora. For each plant species examined, less than 20% of the seeds ingested by captive starlings were not voided, and assumed to be destroyed as the result of passage through the digestive system. Starlings retained the seeds of E. umbellata 29 (mean) ± 19 (SD) min, C. orbiculatus 43 ± 20 min, and R. multiflora 27 ± 9 min. We also examined whether ingestion of seeds by starlings affected the germination of E. umbellata and C. orbiculatus seeds. Seeds that were cleaned by hand or regurgitated by birds had the same likelihood of germinating, and were significantly more likely to germinate than were seeds contained in intact fruit. Defecated C. orbiculatus seeds germinated significantly less well than hand-cleaned or regurgitated seeds, but better than those that were contained in intact fruits. We also found that C. orbiculatus seeds ingested by starlings required significantly less time to germinate than those contained in intact fruits. This study shows ingestion by starlings improves germination for both E. umbellata and C. orbiculatus seeds, and that starlings retain seeds long enough for seed dispersal to occur. Studies to determine the extent to which starlings feed on these plants, and the distances which seeds are moved, are needed.

We established an experiment designed to compare effects of Microstegium vimineum (Japanese stiltgrass) on seedlings of three native hardwood species to investigate the hypothesis that competitive effects of M. vimineum on juvenile trees will vary across different tree species. Growth and survival of Acer rubrum, Liriodendron tulipifera, and Quercus rubra first-year seedlings were compared in plots with and without M. vimineum in three planting beds under 50 percent shade. The tree species studied are abundant and of particular interest in the Central Hardwood Region. A. rubrum and L. tulipifera seedlings experienced reduced growth in several foliar characteristics in the presence of M. vimineum. Q. rubra did not exhibit any differences in foliar characteristics between plots with and without M. vimineum, however there was a reduction in Q. rubra stem weight as a result of the presence of M. vimineum. The differential responses of A. rubrum, L. tulipifera, and Q. rubra to the presence of M. vimineum observed in this study support the hypothesis that effects of this exotic species will vary across tree species. As a result of reductions in the growth of A. rubrum and L. tulipifera, the presence of M. vimineum in forest understories may reduce the rate at which seedlings of these species are recruited into larger size classes.

Herbivores may negatively impact plants by reducing biomass and decreasing fecundity. Rare or endangered plants may be particularly vulnerable to herbivore damage. However, plants may compensate for herbivory by increased growth or reproductive output. We investigated compensatory growth and reproductive effort in Liatris ohlingerae (S.F.Blake) B.L.Robe, a federally-listed herb narrowly endemic to pyrogenic Florida scrub on the Lake Wales Ridge, by conducting biweekly surveys of observed herbivory and an herbivore exclusion experiment. In the field surveys, we assessed the effects of vertebrate herbivory (“topping”) and invertebrate leaf herbivory on plant size and fecundity and compared observed levels of herbivory across sites with different disturbance histories (scrub vs. roadside; scrub sites with differing time-since-fire). In the herbivore exclusion experiment, we compared the effects on plant size and fecundity of excluding vertebrate herbivores (toppers) only vs. excluding both vertebrate and invertebrate herbivores. We found that 62% of plants in the survey had one or more topped stems and that topping occurred more frequently in recently burned sites (< 8 years since fire vs. > 14 years since fire) and in scrub than in roadside sites. Topped plants were significantly shorter and had a greater number of stems (untopped plants only produced 1 stem). Topped plants were less likely to flower, began flowering later in the growing season, and produced fewer inflorescences, infructescences, achenes, and full achenes than untopped plants. Fifty-two percent of surveyed L. ohlingerae plants also showed evidence of invertebrate leaf herbivory with a mean of 24% of leaves damaged. Plants damaged by invertebrate herbivores did not differ significantly in growth or reproduction compared with undamaged plants. In the experiment, exclusion of vertebrate herbivores resulted in taller plants, fewer stems, higher flowering frequency, earlier first flowering, and greater production of inflorescences, infructescences, achenes, and full achenes per plant; plants gained no additional benefits when invertebrates were excluded. Our study demonstrates that L. ohlingerae partially compensates for vertebrate herbivore damage at some sites, depending on the disturbance history. There are population level consequences of undercompensation; vertebrate topping resulted in a 30% reduction in mean fecundity. Future research is necessary to determine if undercompensation jeopardizes the long-term persistence of L. ohlingerae populations.

Most plant species endemic to a rock outcrop system have high constancy to one substrate type. However, the complex geology of the Ozark region of Arkansas and Missouri has promoted a diversity of adaptive strategies and challenged the traditional classifications of edaphic adaptation. For example, the small aromatic mint Satureja arkansana ( =  Calamintha arkansana) has been considered an obligate calciphile, growing abundantly on calcareous rock outcrop communities in the Ozarks and occurring on sandstone outcrops only when plants receive alkaline drainage from nearby calcareous formations. However, we observed in Arkansas that this technically perennial, but functionally winter annual, plant regularly occurs on sandstone outcrops not receiving calcareous effluent. To determine whether this occurrence represented ecotypic specialization or substrate indifference, we compared growth parameters of plants collected from non-alkaline sandstone and calcareous limestone outcrops on their own and the other's native soil. Plants from sandstone outcrops produced significantly greater biomass on native sandstone than on non-native limestone soil. Surprisingly, plants from limestone outcrops also grew better on the non-native sandstone than on their native soil. Other differences in plant growth parameters (e.g., numbers of branches and leaves) between the soil types occurred in both populations and were consistent with the biomass results, although high variances meant that not all parameters were statistically significant. Our results reveal that S. arkansana is not an obligate calciphile, and actually has better growth on sandstone soil, but has a “broad substrate tolerance” that allows success in rock outcrop communities on both substrates.

Understanding the regeneration niche of white pine (Pinus strobus L.) is necessary to promote the restoration of this formerly widespread species. We tested several hypotheses drawn from the literature relating to four features of the regeneration niche for P. strobus: distance to seed source, overstory influence, segregation into spatial neighborhoods, and deer browsing. All hypotheses were tested in a 0.36-ha stem-mapped Pinus resinosa Ait. stand with abundant naturally regenerating P. strobus. Few regenerating P. strobus were found in the immediate vicinity of the seed source tree or other overstory trees and the distribution of distances away from the seed tree differed for very young (< 5 yr) and older regeneration. The spatial arrangement of older regeneration was less associated with the overstory than that of young regeneration, although growth rates were lower in areas of higher overstory influence. Evidence was found for the segregation of regeneration on the basis of size and age classes into spatially distinct neighborhoods, which varied in spatial extent. Spatial segregation was also observed for regeneration that had been browsed, although this was not related to size. Our results supported some hypotheses gleaned from the literature and refuted others, indicating that our understanding of the germination and establishment niches of P. strobus is as yet too immature to predict the factors shaping the regeneration niche.

We examined nutrient cycling responses to prescribed fire on three sub-mesic, mixed-oak sites located in the Blue Ridge Physiographic province of the southern Appalachian Mountains: Alarka Laurel Branch (AL), Robin Branch (RB), and Roach Mill Branch (RM). Each study site was located within a sub-watershed that drained a first order stream. Our objective was to quantify the effects of prescribed burning on forest floor mass, nitrogen and carbon pools; and soil and soil water available nitrogen. Each site included a burned and unburned control area; both burned and control areas were sampled before and after burning. Within each plot, we sampled forest floor mass, carbon and nitrogen, soil and soil solution nitrate (NO₃-N) and ammonium (NH₄-N) concentrations before and after the prescribed burns. All prescribed fires were conducted in the dormant season and were low to moderate intensity. All sites lost a significant amount of forest floor mass due to burning; 82 to 91% of the Oi layer and 26 to 46% of the Oe Oa layer. Soil NH₄-N concentrations increased in surface soils (0–5 cm) only, immediately after burning, but return to pre-burn levels by mid-summer. Burning had no measurable effect on soil solution inorganic nitrogen concentrations. Low levels of solution NO₃-N and NH₄-N after burning and no change in stream NO₃-N concentrations indicated that no inorganic nitrogen was lost from these sites.

Evaluating the factors that regulate woody plant invasion into grassland is important for understanding the process of succession, for predicting potential impacts of global change on grassland ecosystem structure and function and for informing the restoration and management of grasslands. In this study we investigate factors influencing seedling establishment and spatial distribution of an invading native woody plant (Ulmus rubra Muhl.) across a heterogeneous successional grassland landscape in eastern Kansas. Using data collected from a landscape-level seedling census of an abandoned hayfield undergoing succession, we relate U. rubra stem abundance to landscape gradients in topographic position, soil texture, soil fertility, plant productivity, and proximity to seed sources. We also present results from a fertilization experiment to more directly evaluate the potential effect of grassland fertility and productivity on U. rubra invasion, independent from other potential causal factors that covary with soil fertility and plant productivity across the natural topographic gradient. In the landscape census, U. rubra stem densities were greatest in low-productivity micro-sites located at higher elevations in the landscape on hill-slopes and ridges. Highly productive micro-sites at low positions in the landscape and dominated by the introduced rhizomatous hay grass, Bromus inermis, contained few if any U. rubra stems despite close proximity to a seed source. In the fertilization experiment, fertilization increased plant biomass, but reduced U. rubra stem densities, confirming the suppressive influence of high productivity on U. rubra stems in the landscape. In control plots of the fertilization experiment, U. rubra stem density was negatively correlated with distance from seed source, a pattern that was obliterated by fertilization, illustrating the interaction of habitat productivity and dispersal limitation in regulating current patterns of establishment and distribution of invading U. rubra seedlings at the site. We suggest that current patterns of woody plant invasion in this region are very different from what likely occurred historically prior to settlement, due to major anthropogenic shifts in ecological context. This altered context includes the suppression of wildfire, legacy effects of prior agricultural activity and increased availability of woody plant propagules across the region.

Three hundred and ninety-one vascular plant taxonomic entities within 61 families and 219 genera were documented for El Morro National Monument, an area of 419 hectares. These include 140 new non-horticultural records for El Morro and 60 records that had not been recorded in either Cibola County or nearby Valencia County. The checklist includes 55 entities that are exotic to El Morro. One species tracked by the New Mexico Natural Heritage Program, Besseya arizonica (Arizona coraldrops), occurs at El Morro. El Morro is dominated by juniper (Juniperus monosperma) woodland, with ponderosa pine (Pinus ponderosa) in mesic sites, and shrublands in drier sites.