The taxonomy and phylogeny of the perennial North American Apiaceae subfamily Apioideae endemic to western North America (north of Mexico) have posed great challenges to systematists. Available classifications based on morphological characters are in general inconsistent and unsatisfactory, and cladistic analyses based on these data are limited to only a few taxa and a small number of characters. In this study, we scored 54 morphological characters from 123 taxa of North American Apioideae (representing 111 species in 21 genera) to construct an estimate of phylogenetic relationships and to compare the results obtained with those inferred for the group through previous studies using molecular data. The morphological and combined (morphological and molecular) datasets were analyzed using maximum parsimony (with equal, proportional, and successive approximations weighting strategies and Goloboff fit criterion applied to the morphological characters) and Bayesian approaches. Phylogenetic trees derived from morphological characters are largely congruent with those derived from molecular data, upon the collapse of weakly supported branches. The least number of most parsimonious trees is derived from the combined analysis when morphological characters are given proportional weights, and these trees are fully congruent with those derived from molecular data alone. The results revealed that many morphological characters used previously to delimit genera are highly homoplastic, such as the presence of a carpophore, stylopodium, pseudoscape, and dorsal wings, the number of vittae, and the orientation of fruit compression. The results also supported the monophyly of the group, in accordance with previous molecular studies. Three major clades and several well-supported subclades are tentatively circumscribed, thus facilitating future phylogenetic and revisionary studies.

The stem anatomy and pattern of secondary growth in Ungulipetalum filipendulum (Mart.) Moldenke, Cissampelos andromorpha DC., Disciphania hernandia (Vell.) Barneby, Odontocarya vitis (Vell.) J.M.A. Braga, and O. tamoides (DC.) Miers are described for the first time. Their morphology shares features of wood anatomy in common with other Menispermaceae, highlighted by wide rays, pitted tyloses and enlarged vessel pits near the perforation plates. However, unlike other members of Menispermaceae with successive cambia, a single vascular cambium remained functional and showed normal secondary growth. Other characteristics distinguish them from species having stems with successive cambia, such as parenchyma proliferation, new axial segments and type of parenchyma. In fact, it is thought that this pattern of secondary growth indicates that the stem will not develop successive cambia. Since the absence or presence of successive cambia has phylogenetic importance, a methodology which focuses on the patterns of secondary growth may improve the morphological accuracy of stem classification in this family.

A taxonomic revision of the genus Casselia is provided. Casselia is a small genus of Verbenaceae, placed in the tribe Casselieae, along with Tamonea and Parodianthus. It is represented by six species, distributed in South America, along central Brazil, eastern Bolivia and northern Paraguay. Five new synonyms and two lectotypifications are proposed. Detailed morphological descriptions are given for each taxon, as well as a key for their identification, illustrations, actualised synonymy, distribution, and a discussion about the relationship between closely related taxa.

A revision of the Mexican species of the genus Cohniella is presented. Each species is fully described and illustrated. Furthermore, species entries include specimen citation, discussion of diagnostic features and biogeography. A key to the Mexican species of Cohniella is presented. Two new species, Cohniella leptotifolia Cetzal & Carnevali and Cohniella yucatanensis Cetzal & Carnevali, are proposed. Cohniella brachyphylla (Lindl.) Cetzal & Carnevali is morphologically and distributionally recircumscribed. Finally, as part of our ongoing studies in this genus, a non-Mexican species related to C. ascendens, Cohniella teres, is synonymized under Oncidium helicanthum Kranzl. for which the combination Cohniella helicantha (Kranzl.) Cetzal & Carnevali is newly proposed. We provide a key to three closely related, easily confused species, C. aguirrei, C. ascendens, and C. helicantha.

Anisophylly can be defined as the unequal growth of two leaves in a pair from a single branch node. It occurs in several opposite-leafed taxa, even in those with apparently no phylogenetic proximity. We have intended here to classify and describe the anisophylly found in ten species of Melastomataceae from two genera, Leandra and Miconia, using morphometric data. We developed a method to quantify the level of anisophylly in these species, using a parameter called “Anisophylly Index” (AI), with values ranging from nearly 0 (isophyllous) to 1 (strongly anisophyllous). A comparison between the leaves from the erect and lateral branches of Leandra barbinervis showed that this species has incomplete lateral anisophylly; i.e., only the lateral branches are anisophyllous, and in these only the pairs positioned in a dorso-ventral position are unequal, while pairs positioned in a horizontal position are isophyllous. The lateral branches of all species showed incomplete anisophylly. There is no apparent relation between anisophylly levels and area of the leaves. Anisophylly seems to be related to an increase in the efficiency on light capture, and perhaps is controlled by auxins. Its occurrence does not imply a gain or a loss of photosynthetic area of the anisophyllous pair, when compared to the isophyllous pairs in the lateral branches because total leaf area is equal (Table 1). Since the incomplete lateral anisophylly found in Leandra and Miconia is a character whose expression may vary according to environmental conditions and also between different regions of the same plant, it can not be considered as a reliable taxonomic character.

New approaches to underground systems in Brazilian Smilax species (Smilacaceae). Scientific studies show that the watery extract of the thickened underground stem and its adventitious roots of the genus Smilax can act as a therapeutic agent in immunoinflammatory disorders, such as rheumatic arthritis. Brazilians have used this genus of plants in folk medicine, however it is very hard to identify these species, since the morphology of the underground systems is very similar in this group. For better identification of those systems, we studied six species of Smilax L. (S. brasiliensis, S. campestris, S. cissoides, S. goyazana, S. oblongifolia and S. rufescens), collected in different regions of Brazil with different physiognomies and soil characteristics. The main purpose is to describe the morpho-anatomy of the underground systems and to analyze if their structure depends on environmental conditions. The underground stem (rhizophore) is of brown color and it is knotty, massive, slender (S. rufescens) or tuberous (S. brasiliensis, S. campestris, S. cissoides, S. goyazana and S. oblongifolia). The tuberization is a result of primary thickened meristem (PTM) activity. The color and thickness of the adventitious roots change during development because the epidermis and outer cortex are disposed of, so the inner cortex becomes the new covering tissue with lignified and dark color cells. There are differences in starch grain shapes in mature roots. The chemical attributes of the soil are very similar in all studied environments and, even when soil characteristics varied, all the species' underground system was distributed close to the soil surface (10 to 15 cm deep). The species exhibited clonal growth hence their underground system functions as storage structures and the axillary buds can sprout into new stems. Only Smilax rufescens, collected in sandy soil of Restinga, has vegetative dispersal due to the runners.

Historical land use has shaped ecosystem structure and function in much of eastern North America, but the question of how long the legacies of 19^th and 20^th century agriculture will persist in forested landscapes remains a matter of debate. To evaluate whether the legacies of land use are diminishing over time we resampled permanent vegetation plots in areas which either did or did not have an agricultural history. This study focused on changes in trees, shrubs, herbaceous plants, and soil chemistry between 1984 and 2006 at the Cary Institute of Ecosystem Studies in southeastern New York State.  Substantial shifts in tree species composition were observed, including a decline in the basal area of Cornus florida and Quercus prinus. These changes appear to be due, respectively, to dogwood anthracnose and mortality associated with gypsy moth (Lymantria dispar) defoliation. Quercus rubra and Acer saccharum increased in basal area over the same period. Sapling density in the plots remained nearly constant between 1984 and 2006, but seedling density nearly doubled. The invasive herbaceous plant Alliaria petiolata increased markedly in percent cover and frequency of occurrence. Acer rubrum and Q. prinus tree abundances were highly correlated with land use history, while A. saccharum and Q. rubra were not, so the documented changes in forest composition have obscured some of the legacies of land use history on this forest over the past two decades. In addition to the changes caused by novel pests and pathogens, we show how other regional influences on forests (such as fire suppression and invasive plants) may diminish the differences in forest composition between forests with and without agricultural history.

An oak (Quercus spp.)-dominated forest characterized the precolonial vegetation of most of the North American mid-Atlantic region, according to the palynological and written records. There is some evidence, however, of herbaceous communities, especially along estuaries, in very poor soils such as serpentinites, and in areas affected by disturbances caused by windthrows or native Americans. Numerous herbaceous plant taxa, such as Ambrosia spp., grasses (Poaceae) and sedges (Cyperaceae), are native, and predated the arrival of people on the continent. In this palynological study, I found evidence of extensive herbaceous plant communities along the Holocene floodplain of the Delaware River, near Trenton, NJ, between 3,000 and 8,500 years ago, providing evidence for the habitat of these taxa over long periods of time. The plant communities were dynamic, on the scale of millennia, and compare well with current riverine plant communities. This is some of the first evidence for these plant communities existing for millennia in eastern North America in a non-estuarine habitat.

To study the effects of prescribed burning on long-unburned scrubby flatwoods in Cedar Key Scrub State Reserve, FL, USA, we carried out a site analysis to determine if two controls and two treatment sites at preburn conditions did not differ regarding soil, slope, fuel characteristics, plant species structure and composition, and fire history. Sites had the following characteristics: (a) three sites had the same type of soil and the other site a similar one, (b) 0–2% slope, (c) they had not been burned since 1955, and (d) they did not receive mechanical treatment. Therefore, only fuel characteristics and species structure and composition needed to be tested. We installed a grid of 150 × 150 m in each site to quantify moisture content, abundance, and cover. Samples of dry and live fuel were taken in 20 points selected at random to estimate moisture content. We also recorded the abundance and cover of 31 herb and woody species in 50 quadrats (4 m²) selected at random in each site. Moisture content of dry and live fuel did not have significant differences between control and treatment sites. Species richness, diversity, evenness, and species-area curves indicated structural and compositional difference among sites. Similarity coefficients showed some structural similarities among sites. Since these indices drew contradictory results, we performed a cluster analysis, a discriminant analysis, and an F-ratio test to study whether there were differences or not among sites. We found that control and treatment samples grouped in one cluster. Out of 52 variables, only the median abundance of Vaccinium myrsinites Lam. was significantly different between control and treatment sites. Therefore, control and treatment sites were estimated to be ecologically similar, and this methodology could be used for testing control sites for fire ecology research.

Facilitation between different plant species has been documented in terrestrial and marine ecosystems worldwide. The classic example of such positive relationships, the large keystone saguaro cactus (Carnegiea gigantea), always establishes under nurse plants that provide protection to young seedlings through subcanopy climate and environmental modification. Plants (e.g., nurse plants) are not necessarily symmetrical and variations in shape and zone of influence may impact the distribution of other species associated with them. The saguaro is distributed disproportionately to the south of its nurse tree Cercidium microphyllum (palo verde) where subcanopy temperatures are warmer on cold winter nights. I determine whether the tree's canopy shape contributes to the non-random pattern of its protégé cacti in its subcanopy. Data for tree canopy width for each of the four cardinal directions were collected. ANOVA and circular statistics (Rayleigh and V tests) found a significant canopy bias to the southwest. A second dataset shows that Carnegiea are found significantly more often to the south of Cercidium trunks than to the north. When the center of canopy is used rather than the trunk, the statistical bias no longer holds. The observed biases in distribution may be a function of the nurse's canopy shape and resultant microclimate effects. The findings of this study provide an explanation to several already documented observations: 1) winter temperatures are more ameliorated to the south of the trunk than to the north, 2) more of the shade-dependent cacti are found on the south side of their Cercidium nurse's trunk than to the north, and 3) saguaro cacti show a distributional preference to dense-canopied nurses. Variations in nurse canopies become crucial elements of the microenvironment and will alter patterns of establishment and survival of the protégé species that rely on them as even small changes can dramatically alter distributional patterns and expected survivorship. Nurse protection may lead to patterns quite different from the seed rain, and ultimately has a dominant role in the population dynamics of the species.

Species may reach novel habitats through dispersal but nevertheless be restricted in their establishment at different life history stages by local conditions. However, disturbances may alter local conditions within a habitat and hence change establishment outcomes. We investigated the establishment of two non-native weeds of pastures and roadsides, Carduus nutans and Carduus acanthoides, in three contiguous habitats (abandoned pasture, forest edge, and forest) under three disturbance treatments: no disturbance, initial disturbance only (pulse disturbance; i.e., temporary), and initial disturbance with weeding (press disturbance; i.e., sustained). For both species, establishment was not limited by seedling emergence in any habitat, although emergence in the pasture and forest edge relied heavily on disturbance. Combined emergence and survival in the pasture and forest edge were also significantly increased by disturbance, but disturbance had no effect in the forest, where seedlings were unable to survive. Our results show how the spread of a species into different habitats may be limited at different life history stages under different disturbance regimes.

Light and hydrology are believed to have important effects on the population vigor of the globally rare and declining plant Trollius laxus (Ranunculaceae), which occurs in both open and forested geogenous, calcareous wetlands (e.g., rich fens, northern white-cedar swamps) in the northeastern United States. In a forested peatland that supports the largest population of T. laxus worldwide, we explored the relationships between T. laxus vigor and both light (photosynthetic photon flux density) and hydrology at 30 subpopulations. Subpopulation vigor was quantified as abundance (plant and seedling counts), size (stem counts), and reproductive output (flower and follicle counts), and these 5 vigor variables were regressed on 14 light environment and 6 hydrology predictor variables. The two measures of reproductive output were related to a number of the predictor variables, but subpopulation size and abundance were not. Although T. laxus emerges and blooms early in the spring, subpopulation vigor showed similar positive relationships between the spring and summer light environment variables. Vigor had stronger relationships with diffuse light than with direct light. Higher spring groundwater level, the only hydrology variable related to any component of subpopulation vigor, was related to greater follicle production. Because canopy gaps can cause small-scale changes in both light transmittance and hydrology in forested peatlands, our results indicate that gaps may be key to the persistence of T. laxus and other rich fen species during secondary succession.

Notes on some species of Graphis s. str. occurring in the coastal plain of southeastern North America are presented. The use of the name G. pavoniana in the region is discussed. The following species are newly reported from North America: G. hyphosa (Georgia, South Carolina), G. intermedians (Georgia, Florida), G. oxyclada (Florida) and G. pinicola (Georgia, Florida). Graphis intermedians is also newly reported for the Neotropics. Two species with anthraquinone pigments in the lirellae are described as new to science: G. hodgesiana and G. tamiamiensis.