The occurrence of colleters in Eudicotyledons is probably significantly underestimated as a consequence of the scarcity of structural studies directed towards them and the difficulties to determine their function. The present work aims to report the occurrence of colleters in Cariniana estrellensis and describe their morphological and functional aspects; for this, leaves at different stages of expansion were collected and studied using light, and scanning and transmission electron microscopy. The young leaves of C. estrellensis are involute and have colleters along the margins. These colleters appear to be functional in very young leaves and produce pectic secretions that spread over the entire leaf surface. The colleters are clavate and sessile, and have a central axis composed of parenchymatic cells as well as a secretory epidermis covered by a cuticle. The central cells have vacuolate cytoplasm with few organelles and reserve substances. The cytoplasm of the epidermal cells has numerous dictyosomes during the secretory phase, with few plastids and mitochondria. The secretions coating on the leaf surfaces appear to contribute to maintaining the water balance of the young leaves, thus the main function of the colleters in this species appears to be to protect the leaves from excessive transpiration loses.

We recircumscribe Lophiaris carthagenensis (Jacq.) Braem, a species from northern Colombia and Venezuela, and L. oerstedii (Rchb. f.) R. Jiménez, Carnevali & Dressler, from northeastern Mexico to southwest Honduras and Nicaragua. Furthermore, we elevate Oncidium oerstedii var. crispiflorum Schltr. to the status of species as Lophiaris crispiflora (Schltr.) Balam & Cetzal, for populations treated formally as L. carthagenensis of eastern Honduras and central-northeastern Nicaragua to northwest of Panama. Lophiaris carthagenensis is distinguished from L. crispiflora and L. oerstedii by the white or greenish flowers with red brown, wine or magenta spots, characters of the callus, and its disjunct distribution. Finally, we describe and illustrate a new natural hybrid, Lophiaris × oerstelurida Cetzal & Balam. The proposed hybrid is known from a specimen collected in the Colonia Reforma, Acacoyagua, Chiapas, Mexico. Previously, this specimen had been incorrectly proposed as the first record of L. carthagenensis for Mexico; however, the floral morphology suggests it is a natural hybrid between L. oerstedii and L. lurida (Lindl.) Braem.

Impatiens capensis Meerb. (1775) has been naturalized in the British Isles since the early 19^th century. Though native to North America, the species is now established along waterways of lowland Britain and continues to increase its distribution across northern and central Europe. There have been two homonyms of I. capensis for a further two plant species with different sporophytic chromosome number. Impatiens capensis Thunb. (1794) is native to southern Africa, has a sporophytic chromosome number of 2n  =  14, and now carries the accepted scientific species name I. duthieae L.Bolus (1921). Impatiens capensis Boj. ex Baker (1883) is native to Madagascar, has a sporophytic chromosome number of 2n  =  14, and now carries the accepted scientific species name I. firmula Baker (1883). Karyological analyses of plants from three geographically separated I. capensis Meerb. populations from the River Thames Valley proved the sporophytic chromosome number of 2n  =  20 and estimated the mean sporophytic unreplicated nuclear DNA amount of 2C ≌ 1.55 pg, which corresponds to a genome size of approximately 1.51264 Gbp per nucleus.

New species of Aechmea, Quesnelia and Vriesea (Bromeliaceae) are described and illustrated. All species occur in Bahia State, in remnant areas of Atlantic Rainforest.

Climate change predictions for the Great Plains region of North America include increased temperatures and changes to annual precipitation patterns. We used ecological niche modeling (Maxent) to assess how three climate change scenarios published by the Intergovernmental Panel on Climate Change might affect the distribution of the threatened lace hedgehog cactus (Echinocereus reichenbachii) by the 2050s and the 2080s. Under all scenarios investigated, the total land area of suitable habitat for the species increased relative to the current land area predicted as highly suitable by the model. However, under all scenarios, the center of the most suitable area for this species shifted by 160–604 km from the current location in northwest Texas, changing at a rate 20–75 km per decade. While the rate of dispersal in this species is not known, Echinocereus spp. seeds are typically spread by small mammals and it seems unlikely that this species will be able to disperse rapidly. Consequently, the range may initially contract during the coming century, especially in southern Texas where it is most imperiled and where the climate is predicted to become increasingly unsuitable. The current patchiness of distribution of the species suggests that microhabitat characteristics and limitations to dispersal might reduce its actual realized niche relative to the fundamental niche indicated by the models. In addition, land use for agriculture, grazing, and urbanization might further reduce the success of this species in a changing climate.

Studies associated with diaspore self-burial have emphasized the role of awns and substrate surfaces to explain burial differences between species. However, limited research has been conducted to determine the effect of diaspore morphometrics on intraspecific self-burial differences. The aim of this study was to evaluate morphometric and self-burial differences between diaspores of Hesperostipa spartea growing in loam versus sandy soils. Hesperostipa spartea diaspores were collected in three black soil prairies (loam soils) and three sand prairies (sandy soils) in Illinois. Eight morphometric measurements were made from 50 diaspores per site to determine differences between diaspores from these two soil types. Two studies were conducted to determine if self-burial rate and depth of burial differed between diaspores from loam versus sandy soils. Morphometric results showed that sandy soil diaspores were smaller than loam soil diaspores. In addition, regardless of the soil of origin, diaspores were more successful at self-burial in loam soil than in sandy soil due to microtopography. Lastly, diaspores from sandy soil self-buried deeper than diaspores from loam soil regardless of soil substrate. This study demonstrates that there are intraspecific morphometric differences between Hesperostipa spartea diaspores from loam versus sandy soil prairies and that these morphometric differences affect self-burial.

Physaria ludoviciana (Nuttal) O'Kane & Al-Shehbaz (silvery bladderpod) is a state endangered species in Illinois, Minnesota and Wisconsin, the eastern edge of its range. Our goal was to investigate its seed biology (production, dispersal, seed bank longevity, afterripening, seed longevity after storage using germination and emergence, and seedling establishment). This information will be useful for conservation efforts of this endangered species. Over a ten-year period, various seed biology parameters were measured. Infructescences were counted to estimate seed production with 110–744 seeds per reproductive plant. Soil samples were collected at various distances to estimate dispersal where seeds dispersed less than a meter, and also at various times to estimate longevity in the seed bank where only 4% as many seeds were found in November as in June. After-ripening tests used seeds imbibed every two months after harvest for ten months where germination rates increased when imbibition was delayed at least six months. Germination and emergence of stored seed was measured to estimate longevity. Seeds stored at 4 °C and 40–50% relative humidity remained viable for at least six years. For establishment and plant density, seedlings, vegetative plants, and reproductive plants were counted. For establishment, densities were 0–11 seedlings m⁻². This seed biology information could be applied to conservation efforts for this endangered species.

Cyperus entrerianus (Boeckler) (deeprooted sedge, deeproot sedge, woodrush flatsedge) has become naturalized throughout the Texas coastal prairie ecoregion and is now found throughout much of the southeastern United States. Originally from Argentina, its successful naturalization is linked to its rapid growth, morphological plasticity, and generalized habitat requirements, but little work has focused upon its seed biology or ecology. Research was conducted to quantify phytomorphological variability, develop seed yield prediction models, and quantify germination requirements for C. entrerianus to aid in future control and management efforts of this exotic invasive sedge, particularly those focused upon seedbanks. Cyperus entrerianus phytomorphology, seed production, and seed germination were extremely variable among study areas, and provide evidence for its successful naturalization. Although plants varied morphologically, spike cluster area and inflorescence diameter explained much of the variation in seed biomass production. Seed yield prediction models will be useful in monitoring seed production throughout its naturalized range. We estimated that 1300–3100 kg ha⁻¹ seeds could be produced in monotypic stands, although germination rates varied among study areas as well. Seeds collected from larger plants in sites that produced more seeds showed germination rates > 85%. Seeds exposed to imbibition and chilling treatments had reduced germination, although no seed treatments (imbibition, chilling, combinations thereof) depressed germination rates below 63%. Immediate and short-term control and management efforts should focus upon interruption of seed production, via aboveground plant removal, but long-term efforts must target seedbank management. Although seed longevity is not known, seedbank depletion and subsequent integrated management using herbicides and prescribed fire will be required for local and large scale control efforts.

The success of rare plant conservation programs depends upon understanding the ecological factors that regulate seed dormancy and germination. In this study, we characterize the germination niche with respect to temperature and light of three imperiled perennials that are endemic to rock outcrops in the southeastern United States: Astragalus bibullatus, Claytonia ozarkensis, and Conradina verticillata. Our results show that a majority of seeds for each species are unable to germinate at habitat temperatures prevailing after dispersal in early summer. Seeds of the rockface endemic Claytonia ozarkensis germinated to high rates in darkness at 5°C, suggesting germination is confined to winter and that seeds are unable to persist beyond one germination season (transient seed bank). For Conradina verticillata, 44% of seeds germinated without cold stratification, while the remainder required cold stratification and light to overcome physiological dormancy. Following cold stratification, Conradina verticillata seeds germinated in light at cool (15/5 °C) but not at warm (30/15 °C) temperatures, although overall seed viability was low (26%). Seeds of Astragalus bibullatus germinated to low rates (< 10%) in seasonal temperature sequences, confirming that this species forms a persistent seed bank. Seeds of Astragalus bibullatus lost viability following heat shock for 30 min at 125 °C, but germinated to > 50% following mechanical scarification and incubation at 30/15 °C. Results from this study can be used to maximize germination for ex situ and reintroduction programs, and provide insight into managing wild populations.

Ecophysiological studies that investigate species sorting across environmental gradients provide insights into the mechanisms underscoring tree distribution patterns. We examined pine functional traits by measuring a suite of physiological parameters including needle water content, spectral reflectance, transpiration decline, and leaf morphology to explore pine stratification patterns across the elevation gradient of the San Bernardino Mountains in southern California. The high and low elevation species demonstrated moisture and solar radiation tolerance. The lowest elevation species, Pinus attenuata Lem., maintained low transpiration rates under drought stress and had high concentrations of photosynthetic pigments indicating high photosynthetic capacity. Pinus coulteri Don was the most stress intolerant pine as demonstrated by high transpiration rates. Although Pinus lambertiana Doug. dominated cooler north-facing slopes, its lower transpiration rates suggested that it was well adapted to moisture stress. Pinus contorta Doug. was a typical high elevation stress tolerant tree growing under high incident solar radiation, heavy snow pack, and severe winds. Our results suggest that water availability and solar radiation intensity are the major factors influencing southern California pine distributions.