Orbicule characteristics and pollen morphology were studied using light microscopy and scanning electron microscopy with 13 species of Oxalis section Alpinae, endemic to South America. Orbicules are either homogeneous or heterogeneous in size; surface smooth or with punctuations; margin smooth, lobed, or wavy; rounded, oblong, or irregular shapes; variable clustering. | Turkish Journal of Botany Turk J Bot (2016) 40: 637-644 © TÜBİTAK doi: Research Article Oxalis section Alpinae (Oxalidaceae): orbicule diversity and pollen grain morphology 1, 2 Alicia LÓPEZ *, Sonia ROSENFELDT Darwinion Institute of Botany (IBODA – ANCEFN – CONICET), San Isidro, Buenos Aires, Argentina 2 Department of Biodiversity and Experimental Biology, Faculty of Exact and Natural Sciences, University of Buenos Aires, Buenos Aires, Argentina 1 Received: Accepted/Published Online: Final Version: Abstract: Orbicule characteristics and pollen morphology were studied using light microscopy and scanning electron microscopy with 13 species of Oxalis section Alpinae, endemic to South America. Orbicules are either homogeneous or heterogeneous in size; surface smooth or with punctuations; margin smooth, lobed, or wavy; rounded, oblong, or irregular shapes; variable clustering. According to orbicule characteristics, six groups are proposed. The Oxalis pollen grain is 3-colpate and the shape is prolate spheroidal, oblate spheroidal, or spheroidal; ambit rounded or triangular. Exine microreticulate, semitectate, brochate. Brochi circular, oval, triangular to polygonal. Lumen with or without content. Sporopollenin generally forming groups that may be in rows in the margins or in the center of colpus. Key words: Andes, Argentina, Chile, South America, Oxalis pollen, Ubisch bodies 1. Introduction Oxalis L. (Oxalidaceae) is a diverse genus comprising approximately 500 species. The genus is divided in four subgenera: Oxalis L., Monoxalis (Small) Lourteig (1980), Trifidus Lourteig (1995), and Thamnoxys (Endl.) Reich. emend. Lourteig (2000) (Lourteig, 1994, 1995, 2000). Section Alpinae is included in subgenus Oxalis, originally published by Reiche in 1894. The species in this section can be described as follows: annuals or perennial herbs, cushion-like loose to very dense, 1–30
