Introduction

The Cucurbitaceae is a family of herbaceous and woody vines concentrated in tropical regions of the world, and much appreciated for their edible and useful fruits (cucumbers, squashes, melons, and gourds). While the economically important members of the Cucurbitaceae have received much attention by botanists, those wild genera not historically domesticated by humans are also worthy of study. Gurania (also known as the "Jungle Cucumber") is one of the largest genera in the Cucurbitaceae, with an estimated 40-75 species growing throughout the New World tropics. Gurania flowers are showy, with an orange to red calyx (sepals)-- a character not found elsewhere in the Cucurbitaceae. The petals are tiny, yellow, and mostly hidden by the large sepals, which attract the hummingbirds and Heliconius butterflies that pollinate the flowers. Gurania plants are monoecious, meaning that flowers are only of one sex, but both male and female flowers can be produced on a single plant. However, they are not both produced on one plant at the same time, so plant-to-plant movement by pollinators is neccessary for fertilization. The green, pickle-sized fruits of Gurania are known to be dispersed by bats in the genus Phyllostomus, and are probably eaten by several bird species as well. Current experts in the Cucurbitaceae, not to mention non-specialists, find Gurania species notoriously difficult to identify with certainty. But these showy and ecologically important plants are found in nearly all moist lowland and montane forests in the Neotropics, and researchers conducting floristic and ecological studies in these regions need to identify the plant species they encounter. No single publication contains keys and descriptions for all the species of Gurania. Such a publication, known as a monograph, is the goal of my doctoral research at the New York Botanical Garden. During two months of field research on Gurania at the Los Amigos Biological Station in Madre de Dios, Peru, I was fortunate to be able to find and study five species of Gurania, growing and reproducing sympatrically (in one area and simultaneously). Previously, only two common Gurania species had been identified in the Los Amigos Conservation Area. Three more species of restricted habitats were discovered at the station in the course of my study. With the assistance of the staff of the Amazon Conservation Association (ACA) and the Asociación para la Conservación de la Cuenca Amazónica (ACCA) at Los Amigos Station, and with laboratory equipment available at the station's botanical laboratory, I have come to know these five Gurania species intimately. Through weeks of pollination activity observation, habitat investigation, macro- and micro-photography, and collection of preserved plant samples for herbarium study, I have accumulated a great deal of data. This work has also given me a greater understanding of the characteristics that both demonstrate directional selection (driving the evolution and divergence of species) and define the differences between species (allowing me to create useful keys and descriptions so that non-specialists can identify these plants). This was an excellent place to gain experience with Gurania that I can put to use in the herbarium and in future fieldwork at other sites. This ongoing study was conducted in collaboration with the Botany of the Los Amigos Conservation Area project.