Flora and physiognomy of Caatinga vegetation over crystalline bedrock in the northern Caatinga domain, Brazil

Abstract The Seasonally Dry Tropical Forests and Woodlands biome (SDTFW) has its largest nucleus in the Caatinga domain. We characterized the flora and physiognomy of the vegetation in the Pedra da Andorinha Wildlife Refuge (RPA), in Ceará, Brazil. Plant collections were made between March/2015 and May/2021, applying usual botanical methods. All material was deposited in HUVA herbarium. The phytosociological studies covered five 50 m x 50 m plots established (1.25 ha) in which all individuals with diameters at soil level ³ 3 cm were inventoried. We identified 266 vascular plants species distributed among 185 genera and 67 families, including one fern (Marsilea deflexa - Marsileaceae). Fabaceae had the greatest species richness (38 spp.), while Ipomoea was the richest genus (9 spp.). 43.6% of all plant species were herbaceous, with a predominance of therophytes (57.5% of all herbaceous plants). The phytosociological study sampled 1,988 individuals distributed among 24 species of 13 families. The species with the greatest important value were Cordia oncocalyx (Boraginaceae) and Croton blanchetianus (Euphorbiaceae). We classify the local physiognomy as typical caatinga sensu stricto vegetation and rocky vegetation on inselbergs and outcrops. We highlight the richness of herbaceous plants in the local community, which surpass the richness of the woody component.