zanthoxylum achidek (Rutaceae), a new species from the forested tops of south-east Sierra de Lema (Bolívar State, Venezuela) is described and illustrated. The most distinctive characters from its Guianian relatives are its 2-3 (4) pairs of very large and entire leaflets margin, and its showy inflorescences that can exceed 30 cm high.

corallophila verongiae represents the first report for Venezuela, it was found growing on coralline substrata in the sublittoral, 6-9 m depth, at two coral reef sites in Morrocoy National Park, Venezuela. The characteristics of the Venezuelan specimens correspond with the more recent description of this species. This report extends the c. verongiae distribution to the southern Caribbean.

Flowering, unripe fruit production, and fruit maturation were evaluated for 171 species belonging to 57 families of angiosperms in the vegetation of the Venezuelan Central Plains at Estación Biológica de los Llanos. The main goal of this study was to establish the correlation between reproductive phenology and six climatic variables according to plant life form, habitat, and overall community. Monthly values of precipitation and relative humidity are positively correlated, and monthly values of evaporation and temperature are negatively correlated with the number of lianas, perennial herbs, and annual herbs, the contrary was found for the number of tree species with flower. The number of plant species with flowers was negatively correlated with temperature and evaporation, and positively correlated with relative humidity and precipitation for forest-savanna transition, savanna, disturbed area, and overall community. Insolation was negatively correlated with flowering in the forest and forest-savanna transition. Precipitation was only correlated with the number of flowering plant species in the forest. The number of species with unripe fruits was positively correlated with the relative humidity for shrubs, perennial herbs, and annual herbs, and with precipitation for shrubs and perennial herbs. On the contrary, species with unripe fruits was negatively correlated with radiation for trees, temperature for herbaceous species, and evaporation for shrubs and herbaceous species. The number of lianas with unripe fruits was only correlated with temperature. The total number of species with unripe fruits was negatively correlated with temperature and evaporation for the four habitats, and positively correlated with the relative humidity at the community level. In addition, unripe fruits were negatively correlated with radiation and positively correlated with precipitation in the forest. Fruit maturation of shrubs and perennial herbs were negatively correlated with temperature and evaporation, and positively correlated with relative humidity. In addition, fruit maturation of lianas were negatively correlated with relative humidity and precipitation and positively correlated with evaporation. The number of plant species with ripe fruits was only positively correlated with radiation for the forest. In general, the reproductive phenology was positively correlated with climatic variables related to water availability and negatively with the climatic variables associated with water deficiency. These correlations suggest that reproductive phenology may co-vary according to particular attributes of the climate depending upon plant life form and the habitat of the community.

The species of the Lantana genus are known by the high commercial value of its natural oils, but their photosynthetic response to environmental variables is not well known. To characterize the photosynthetic capacity and establish the effect of water deficit on photosynthesis, plants of three Lantana species (L. caracasana, L. canescens and L. camara) were submitted to water deficit by holding watering.The highest diurnal carbon assimilation was observed in L. caracasana and water deficit caused a decline in water potencial, photosynthesis and stomatal conductance of all species. Changes observed in variable fluorescence, apparent quantum yield and photosynthesis at saturated light, suggested a down regulation of photochemical activity of photosystem II during water deficit. In well irrigated plants, slight differences were observed among species in the photosynthetic response to intercellular CO2 concentration. Optimum temperature of photosynthesis was within 25-26ºC. The effect of water deficit on the photosynthetic parameters varied with the species, being L. camara the most affected.

To characterize the commercial trade of medicinal plants in Caracas, Venezuela, five popular markets and 10 herb stalls were visited. Stall keepers were interviewed to determine which species were being sold and which were their traditional uses. One hundred ninety eight samples were recorded and 164 species from 72 families were identified. Most of these species are cultivated although wild species from theAndes and Guayana have also been commercialized. One hundred twenty different uses of these plants were recorded and categorized according to 18 disease types, especially those associated with digestive system, infectious and parasitic diseases, as well as those related to skin and subcutaneous tissue. Multi-purpose species were dominant (164, IVF > 0,5), while 125 species show significant use (NUS > 20%). The cluster analysis evidences two groups of stalls. A complementary study considering pharmacological and ecological assessments is recommended.

The effect of seasonal changes in water depth in an herbaceous, permanently waterlogged wetland on the nitrogen concentration of Hymenachne amplexicaulis is reported (Miranda State, Venezuela). The soil’s nitrogen concentration increased from February to December. Nitrogen mean concentration was higher on dead aboveground biomass, followed by leaves, inflorescences and stems. Total nitrogen was lower on December and higher on August. Net absorption and N-use efficiency of leaves and stems showed different behaviors study period. Seasonal changes of water depth influenced concentration, absorption and nitrogen-use efficiency by the grass H. amplexicaulis.

As part of the floristic inventory of some disturbed areas for gold and diamond’s alluvial mining in Bolívar State five localities were studied during the years 1992 and 1993. Mining activities cause holes, mood ponds and tails. In each locality the tails were divided in four areas according to the substrate and the plants were collected. The first herbs and sufrutescent plants showed at edges of the ponds and holes. Asa-Karón is the richest locality, followed by Supamo-Parapapoy, El Polaco, Bochinche and Guaniamo. cyperus odoratus, c. luzulae, Fuirena umbellata, Pityrogramma calomelanos, Trema micrantha and Phytolacca rivinoides are common species at the majority of the localities. The families with more species are Poaceae, Cyperaceae, Leguminosae, Melastomataceae, Asteraceae, Rubiaceae, Solanaceae, Onagraceae, Bignoniaceae and Clusiaceae.

A taxonomic revision of the species of the genus Machaerium in Venezuela is presented to elucidate knowledge about the nomenclature and identification problems through the history of this taxon. As result 39 species and 11 varieties distributed in the Venezuelan territory between 0-1800 m asl were determined. A key for identification of the taxa based on foliar morphology pattern and the description of them is presented. M. capote, M. isadelphum, M. milleflorum and M. seemannii are consolidated as new records to the Venezuelan flora. The endemic species M. dubium, M. grandifolium, M. guaremalense, M. striatum, M. orthocarpum, M. tovarense and M. truxillense are reasserted. Anew combination: Machaerium arboreum (Jacq.) Benth. var. cultratum (Pittier) Meléndez is proposed. By means of this study basic information about phytodiversity of the country and the neotropical region flora is attained.

Wood anatomy of 14 species of the genus Pouteria Aubl. (Sapotaceae) growing in Venezuela was studied. The following species were studied: P. amygdalicarpa, P. caimito, P. coriacea, P. cuspidata subsp. dura, P. decorticans, P. egregia, P. eugeniifolia, P. guianensis, P. hispida, P. macrophylla, P. procera, P. reticulata, P. trilocularis and P. venosa. Wood description was done according IAWACommittee list. An one wayANOVA and Tukey test for multiple comparisons was performed regarding quantitative features. Secondary xylem shows homogeneity in Pouteria genus; the main distinctive features between species are pore diameter, pit diameter, rays width and number of wide cells in parenchyma bands. According to these features, a dichotomous key was elaborated. Pouteria decorticans and P. hispida can only be separated using quantitative features like diameter of intervessel pits. Similar case was observed between P. egregia and P. procera, separated by fibre length.