The Araceae in Ceará, Brazil: humid forest plants in a semi-arid region

Abstract

The study consists of a taxonomic treatment of the Araceae of Ceará, a state lying within Brazil's semi-arid region. The aroid flora shows greater similarity to those of central Brazil and Amazonia than to the Atlantic forest. Most species occur in humid forest fragments - the "florestas serranas". Geophytes are also found in caatinga and dry forest (Taccarum ulei) and lithophytes on rock outcrops in dry forest (Philodendron acutatum). Floating aquatics occur in ponds and lakes throughout the state (Pistia stratiotes, Lemna aequinoctialis, Lemna minuta, Spirodela intermedia, Wolffia columbiana, Wolffiella welwitschii), and freshwater helophytes (Montrichardia linifera) along river margins. 28 taxa (species and varieties) in 19 genera are described and most are illustrated:Anthurium (three spp.), Caladium (one sp.), Dieffenbachia (one sp.), Dracontium (one sp.), Lemna (two spp.), Monstera (two spp., one with two varieties), Montrichardia (one sp.), Philodendron (four spp.), Pistia (one sp.), Scaphispatha (one sp.), Spathicarpa (one sp.), Spathiphyllum (one sp.), Spirodela (one sp.), Syngonium (one sp.), Taccarum (one sp.), Wolffia (one sp.), Wolffiella (one sp.), Xanthosoma (two spp.), Zomicarpa (one sp.). New records for Ceará are Dieffenbachia aglaonematifolia, Dracontium nivosum, Monstera adansonii var. laniata, Philodendron sp. aff. ruthianum and the naturalized exotic Typhonium roxburghii. An identification key and data on geographic distribution and conservation status are provided.