1. Department of Botany Universidade Federal de Pernambuco Recife, Pernambuco 50670‐901 Brazil
2. Plant Ecology and Systematics University of Kaiserslautern Kaiserslautern, PO Box 3049, 67663 Germany
3. Department of Botany Unidade Acadêmica de Serra Talhada, Universidade Federal Rural de Pernambuco Serra Talhada, 56909‐535 Pernambuco Brazil