Summary Clusia reginae (Clusiaceae) is described using an integrative taxonomy approach. Field observations, discriminant analyses of morphological characters and phylogenetic inference based on molecular data led to the recognition of a new species of tree. This new taxon is distinct for having broadly obovate leaves, white petals, bright yellow flower resin and relatively large fruits. Clusia reginae is known from the foothills and valleys of the Venezuelan Andes and is here assessed using IUCN criteria as Vulnerable.

Chusquea subg. Swallenochloa comprises 52 species distributed in five biogeographical areas (Mexican Transition Zone, Brazilian subregion, South American Transition Zone, Chacoan subregion, and Andean region). Species of the subgenus grow from almost sea level in the Andean region to almost 4000 m in the northern South American Transition Zone (SATZ) and are often common or dominant elements of the vegetation. In this study, three questions related to species richness, endemism, and risk category of Chusquea subg. Swallenochloa were addressed. Analyses were based on the geo-referenced occurrence data of these 52 species, using different methods and software programs. Results indicate that the Chacoan subregion and SATZ had the highest richness with 16 and 15 species, respectively. The area of highest endemism was found in the Brazilian subregion. The AOO and EOO methods provided strongly differing estimations of conservation status.

High mountain ecosystems are subjected to frequent freeze–thaw events all-year round, consequently plants have developed freezing resistance mechanisms to cope with extreme low temperatures. Additionally, these events have also been correlated with the risk of cavitation so that plants need to adapt their water transport system. Information on freezing resistance and xylem vessel characteristics along elevation gradients is scarce for neotropical high elevation species. In this study we aboard two specific questions: 1. Are there intraspecific differences in freezing resistance between low and high elevation populations of Senecio formosus Kunth? 2. Could an increase in freeze–thaw cycle frequency and lower freezing temperatures at higher elevations determine differences in xylem conduit traits between low and high elevation S. formosus populations? We expect greater freezing resistance and a safer water transport system, mainly shaped by narrower tracheary elements in higher elevation populations compared to lower ones. Freezing resistance (avoidance and tolerance) and tracheary elements were studied in S. formosus at its lower (3100 m) and upper (4200 m) distributional limits in the Venezuelan paramo. Freezing resistance was determined through injury and freezing temperature determinations; whereas xylem conduit characteristics dealt with were: vessel element and tracheid diameters,

Flowering cycles are poorly understood in the majority of woody bamboos, since their frequency and duration may vary according their growth-form and distribution across latitude and altitude ranges. Tropical Andean bamboos are known for combining gregarious (asynchronic) and asynchronic flowering events; the main objective of this study was to determine the flowering pattern of Chusquea mollis Swallen) L.G. Clark (= Neurolepis mollis Swallen), a monocarpic, native bamboo that grows in the subparamos and paramos of Venezuela and Colombia. The chronology of flowering events of this species was based on the revision of herbarium specimens, online databases and the occurrence of flowering events in two populations of the Cordillera de Mérida, Venezuela. Taking in account that age diversity may also contribute to identify flowering patterns in bamboo populations, we performed a survey of a single population located in the Páramo La Aguada. Our results suggest that C. mollis combines gregarious and asynchronic flowering cycles, after a relatively short vegetative period (5-7 years). The census conducted in a single population of La Aguada revealed the co-existence of plantlets, juvenile plants, vegetative, reproductive and post-reproductive adults, of which the juvenile were the most numerous group.

Bamboos are a diverse and ecologically important group of plants that have the potential to modulate the structure, composition, and function of forests. With the aim of increasing the visibility and representation of bamboo in forest surveys, and to standardize techniques across ecosystems, we present a protocol for bamboo monitoring in permanent research plots. A bamboo protocol is necessary because measurements and sampling schemes that are well‐suited to trees are inadequate for monitoring most bamboo species and populations. Our protocol suggests counting all bamboo culms (stems) in the study plot and determining bamboo dimensions based on two different approaches: (a) measuring a random subset of 60 culms and calculating the average dimensions or (b) measuring all culms. With data from 1‐ha plots in the Peruvian Andes, we show that both approaches provide very similar estimates of bamboo basal area. We suggest including all mature culms rooted inside change the to each plot from all woody bamboo species with maximum diameters ≥1 cm. We also present recommendations on how to collect vouchers of bamboo species for identification. Data collected according to our proposed protocols will increase our understanding of regional and global patterns in bamboo diversity and the role of bamboo in forest dynamics.

Background: Woody bamboos of the genus Chusquea grow along a broad range of elevations in the Venezuelan Andes. Their growth-form and density vary along the cloud forest – páramo gradient. In this article, we related ecophysiological traits and population genetic diversity information to explain the distribution of growth-form patterns of Chusquea in the Merida Andes, Venezuela. Aims: We quantified differences in the ecophysiological response and genetic diversity of scandent cloud forest and shrub-like páramo bamboos of the genus Chusquea, taking in account the differences in their flowering patterns, growth-form and habitat. Methods: We related low temperature resistance, water relations and leaf gas exchange variables to the growth-form, habitat, flowering patterns and genetic diversity in species of Chusquea. The genetic diversity study was based on Inter Sequence Simple Repeats and Random Amplified Polymorphic DNA markers analysis of cloud forest and páramo populations. Results: Scandent cloud forest and shrub-like páramo species of Chusquea had a very similar ecophysiological response for all the variables analysed during wet and dry seasons and were capable of enduring freezing temperatures through moderate supercooling. Species associated with the cloud forest – páramo gradient maintained low stomatal conductance and transpiration rates that favoured high leaf water potentials, without limiting photosynthetic rates. Shrub-like bamboos growing above the continuous forest line had a small decline in net photosynthesis rates, associated with an increase in water use efficiency. Both scandent and shrub-like bamboos had a remarkably high genetic diversity, comparable to non-clonal species. Conclusions: Species of Chusquea in the Venezuelan Andes are a physiologically relatively homogeneous group across a broad elevation gradient. Population genetic diversity appears to be more related with their flowering pattern and habitat conditions than with their growth form.

Chusquea fendleri Munro es un bambu trepador con amplia distribucion en los bosques nublados de Venezuela, que abarca desde la Serrania de Turimiquire hasta la cordillera de Merida. Dada la amplia distribucion y notoria variabilidad foliar de la especie en el pais, se realizo un estudio morfoanatomico con especimenes procedentes de 11 localidades diferentes. El estudio comparativo incluyo siete caracteres morfologicos diagnosticos y 28 caracteres anatomicos foliares, siguiendo metodos clasicos de morfoanatomia vegetal. Los caracteres morfologicos de utilidad taxonomica fueron: longitud de la ligula interna, contorno, consistencia y superficie de la lamina foliar; los anatomicos, espesor del mesofilo, presencia/ausencia de macropelos y tipos de micropelos. Con base en los caracteres estudiados, se elaboro una clave dicotomica para identificar cinco biotipos locales de C. fendleri .

Chusquea fendleri is a scandent woody bamboo, described originally by August Fendler, based on a single collection of the Colonia Tovar, located in the State of Aragua, in Northern central mountains of Venezuela. Further collections carried out in the last 30 years revealed that C. fendleri has a very broad geographic and altitudinal distribution in Venezuela (1,700-2,750 m a.s.l.), which we believe is the cause of the conspicuous morphological variability observed across the country and the source of local and regional phenotypes. The aim of our research was to determine whether these phenotypes should be included in C. fendleri, or considered new species. An extensive sampling was carried out, which included all of the voucher specimens available in national and regional herbaria, as well as fresh specimens, collected in field trips conducted in different cloud forests of the Venezuelan Andes that had not been sampled previously. Our study consisted of a comparative analysis, based on morphological characters and microsatellite markers. The morphological analysis included only vegetative characters, since over 80% of the study specimens collected were infertile. The genetic analysis was based on PCR amplifications of 7 SSR markers designed for Guadua angustifolia, given that no SSR markers have been developed for this genus. 43 morphological characters were analyzed, of which 18 varied consistently and considered informative. Of the 7 SSR markers assayed, only 3 detected polymorphic alleles of use to separate closely related populations. The morphological analysis revealed the existence of three distinctive phenotypes, whereas the genetic analysis only two. Based on the morphological and genetic analysis, we recognize two morphological phenotypes of C. fendleri and a potentially new, sister species.

Guadua amplexifolia and Guadua angustifolia are the most promising timber substitutes amongst American bamboos due to their outstanding dimensions and structural properties. Despite the commercial potential of these species, there are few studies on the survival and adaptability of juveniles in plantations. The present study dealt with survival, growth, and ecophysiological response of juvenile clonal plants of these species, cultivated in abandoned pastures in Mérida, Venezuela. Survivorship, growth (height and culm diameter), and ecophysiological parameters were monitored the first year during wet and dry seasons. Survival rates were high in both species (95% in G. amplexifolia and 89% in G. angustifolia). Midday leaf water potentials decreased in both species during dry months (–1.28 to–2.72 MPa in G. amplexifolia and–1.67 to–2.37 MPa in G. angustifolia, respectively). Net photosynthetic rates measured during wet [16.57 ± 1.40 and 13.68 ± 2.40 μmol(CO2) m–2 s–1, respectively] and dry seasons [12.19 ± 2.82 and 8.12 ± 1.81 μmol(CO2) m–2 s–1, respectively], demonstrated that G. amplexifolia maintained consistently higher photosynthetic rates compared to G. angustifolia, which could explain the higher growth rates of the former. Similar trends were observed for stomatal conductance, transpiration, water-use efficiency, electron transport rate, and photochemical quenching of PSII. G. angustifolia maintained higher nonphotochemical quenching as well as a higher consumption of electrons per molecule of CO2 fixed, indicating a lower photosynthetic efficiency. The maximal photochemical efficiency of PSII (0.73–0.76) suggested that neither of these species suffered from photoinhibition, despite persistently high radiation and air temperatures at the study site.

Chusquea purdieana is a previously poorly known species of woody bamboo (Poaceae: Bambusoideae: Bambuseae) from northern Colombia characterized by a scandent habit, a large number of leafy subsidiary branches per node, and narrow foliage leaf blades. A morphological analysis of similar collections from Venezuela and Colombia allowed us to distinguish two new species from the Venezuelan Andes, C. aurea and C. multiramea, based on a combination of vegetative and reproductive features. We here describe and illustrate the new species and we also provide a detailed redescription of C. purdieana, along with illustrations of its most diagnostic features. We report the occurrence of C. purdieana in Venezuela and document a broader range for the species in Colombia.

Chusquea purdieana, C. serrulata y C. spencei son los tres bambúes leñosos más comunes en los Andes venezolanos, las dos primeras son trepadoras del bosque nublado y la tercera es un arbusto asociado al bosque preparamero-arbustal paramero. Con el objeto de determinar la influencia de la forma de vida, hábitat, estructura morfoanatómica y altitud sobre la respuesta ecofisiológica de estas tres especies, se realizaron análisis multivariados incluyendo tanto atributos ecofisiológicos como morfoanatómicos a lo largo del gradiente bosque nublado-páramo (2450-3320 m snm). Los atributos ecofisiológicos analizados fueron aquellos involucrados en la respuesta hídrica, intercambio de gases, contenido de nitrógeno foliar y eficiencia en el uso del nitrógeno. Los morfoanatómicos: área foliar específica, diámetro de vasos caulinares y densidad estomática. Los estudios ecofisiológicos y mediciones microclimáticas se realizaron a 2450 m en el caso de las especies trepadoras, a 3025 y 3320 m en el de la arbustiva. Los análisis multivariados basados exclusivamente en atributos ecofisiológicos revelaron una marcada uniformidad en este género, que impidió separar a estas especies en función de su forma de vida, hábitat y distribución altitudinal. Sin embargo, cuando se analizaron en conjunto atributos ecofisiológicos y morfoanatómicos se obtuvo tanto una segregación interespecífica como entre formas de vida. La homogeneidad fisiológica observada en este grupo se atribuyó en primer lugar, a su estrecha asociación a condiciones de elevada humedad y nubosidad, y en segundo lugar, a que Chusquea constituye un grupo relativamente nuevo, en el que la diversificación morfológica no se refleja en un nivel fisiológico.

The morpho-anatomical vegetative structure and water-storing strategies of two orchids of the Venezuelan Cloud Forests, Pleurothallis cardiantha and Maxillaria miniata, are described for the first time. Field work was conducted in a relatively preserved Cloud Forest and a secondary forest of the Botanical Garden of the Universidad de los Andes, Venezuela, located in the same vicinity. Botanical specimens were stored in FAA and submitted to standard plant anatomy microtechnique procedures, including SEM. Monthly leaf-water potentials were recorded during 2004-2005 in order to determine whether these species behave as typical CAM, facultative CAM or C, species. Both exhibit xeromorphic characters in their vegetative organs. M. mineata presents pseudobulbs as main water storing structures, thin cartaceous leaves, epidermal and sclerenchymatic tissues associated with siliceous crystals, adaxial hypodermis double layered, single-layered abaxial hypodermis, homogenous mesophyll with well developed collateral bundles, and abundant sclerenchyma. P. cardiantha, in contrast, presents moderately succulent to coriaceous leaves, adaxial epidermal cell forming papillae, heterogenous mesophyll with poorly developed vascular bundles. The water-storing tissues in this species involve the adaxial and abaxial hypodermis, as well as the acuiferous idioblasts located in the spongy parenchyma. The leaf water-potentials registered were high and remained practically invariable during the year, which suggests a typical CAM metabolism in both cases.

Se describen por primera vez la estructura morfo-anatomica y estrategias hidricas de dos orquideas de las selvas nubladas andinas de Venezuela, Maxillaria miniata y Pleurothallis cardiantha. El estudio se efectuo en una selva nublada poco intervenida y en el bosque secundario del Jardin Botanico de la Universidad de los Andes, Venezuela. Las muestras recolectadas fueron fijadas en FAA y sometidas a metodos tradicionales de anatomia vegetal y de MEB. Se determinaron sus potenciales hidricos foliares durante el ano 2004-2005, para determinar si presentan un comportamiento CAM tipico, CAM facultativo o C3. Ambas especies exhiben caracteres xeromorficos en sus organos vegetativos. M. miniata presenta seudobulbos como principales reservorios hidricos, hojas delgadas cartaceas, celulas epidermicas de paredes engrosadas, hipodermis adaxial biestratificada y abaxial uniestratificada, clorenquima homogeneo con haces bien desarrollados, abundante esclerenquima, y cristales siliceos asociados a tejidos epidermicos y esclerenquimaticos. En contraste, P. cardiantha presenta hojas suculentas a coriaceas, epidermis adaxial papilosa, mesofilo heterogeneo, haces pequenos, poco desarrollados e hipodermis acuifera pluriestratificada en ambas caras, que junto con los idioblastos acuiferos del clorenquima constituyen los tejidos de reserva de agua. Los potenciales hidricos registrados en estas especies se mantuvieron elevados y casi invariables durante todo el ano, lo cual sugiere un metabolismo CAM en ambos casos

In the Sierra Nevada National Park, in Mérida, three species of Miconia (Melas- tomataceae) occur between 3.000 and 4.000 m asl. These species are: M. chionophylla, M. latifolia and M. tinifolia. The first is a dwarf shrub of the Polylepis sericea forests, whilst the other two species are trees of the upper montane forests. With the purpose of describing and comparing these three species, their distribution and habitat, the mor- phoanatomical characters of the leaves were studied in samples collected from individu- als growing at different altitudes, along this gradient. Miconia latifolia and M. tinifolia reach 3.500 m and exhibit typical xeromorphic leaves: reticulated vein pattern, thick cuti- cles, elevated stomatal density, small epidermic cells, multistratified hypodermis and a compact mesophyll. M. chionophylla, instead, exhibits typical mesomorphic leaves, characterized by a lax vein pattern and mesophyll, thin cuticles, relatively low stomatal density and lacks a hypodermis, yet reaches 4.000 m asl.