Pedro Luis Ortiz

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The occurrence of cyathia containing staminate flowers but lacking a pistillate flower was studied in 17 species of Euphorbia. Male cyathia were found in the majority of species studied (88.2%) giving functional andromonoecy. In the male cyathia, the pistillate flower is generally totally absent, but sometimes a vestigial pistillate flower with a(More)
Apomixis and adventitious polyembryony have been reported for several species of Bombacoideae, including Eriotheca pubescens, a tree species of the Neotropical savanna (Cerrado) areas in Brazil. However, the origin of polyembryonic seeds and their importance for the reproduction of the species remained to be shown. Here, we analyzed the early embryology of(More)
BACKGROUND AND AIMS The genus Cytinus is composed of rootless, stemless and leafless parasites whose flowers are only visible during the reproductive period when they arise from the host tissues. Most of the taxa occur in Madagascar and South Africa, where mammal pollination has been suggested for one species. There is only one species in the Mediterranean(More)
The hypothesis that reproductive cost differs between sexes was tested in Juniperus communis subsp. alpina along an altitudinal gradient. Sex ratio (male : female) increased significantly with elevation, and above 2,600 m it was significantly male-biased. The reproductive effort was markedly greater for females than for males at all elevations. However,(More)
The distance of explosive dispersal, its pattern in time, and the relative importance of autochory have been studied in two diplochorous species: Euphorbia boetica and E. nicaeensis. The seeds of E. boetica released by explosive dispersal reached a median distance of 156 cm and a maximum of almost 8 m, while the distances reached by the seeds of E.(More)
BACKGROUND AND AIMS Rumex bucephalophorus subsp. canariensis is an endemic taxon to Macaronesia with diaspore polymorphism. The origin and colonizing route of this taxon in Macaronesia was studied using molecular data and information on diaspore types. METHODS Amplified fragment length polymorphism (AFLP) was used in 260 plants from 22 populations of R.(More)
Pollen limitation, resource limitation, fruit abortion, and predation have all been proposed as factors explaining low fruit set in hermaphroditic plants. We conducted a 5-year study combining field observations and pollination experiments to determine the causes of the low fruit set in Aristolochia paucinervis, a Mediterranean species with a specialized(More)
Floral symmetry and fusion of perianth parts are factors that contribute to fine-tune the match between flowers and their animal pollination vectors. In the present study, we investigated whether the possession of a sympetalous (fused) corolla and bilateral symmetry of flowers translate into decreased intra-specific variability as a result of natural(More)
UNLABELLED • PREMISE OF THE STUDY Whole genome duplication (WGD) and specific polyploidy events marked turning points for angiosperm genome structure and evolution. Therefore, cytogenetic studies of polyploidy-prone groups such as the tropical Malvaceae and plant formations such as as the Brazilian Cerrado have gained further importance. We present new(More)