title: Flower structure and developmental stages of the capitulum of Smallanthus sonchifolius (Asteraceae): reproductive implications.
abstract: Yacon (Smallanthus sonchifolius, Asteraceae) is an ancient andean crop that has numerous dietary and medicinal properties. Morphological and anatomical features and developmental changes of the capitulum were studied. A ray floret is a pistillate, female flower, while a disc floret is a staminate male flower, and the former opens before the latter, being pseudanthium protogynous. The capitulum presents interesting attributes for pollinators such as flower structure, nectaries and pollenkitt. Gynoecial nectaries were found on undeveloped ovary in the disc floret, but not in the ray floret. Glandular trichomes were observed on the abaxial epidermis of corolla in the ray floret, but not in the disc floret. Capitulum development was divided into eight stages. Stigma receptivity varied with these stages. Pollen viability was low (15%). In accordance with low viability, pollen grains exhibit diverse sizes and shapes, reduction in length of spines, and abnormal protoplasm. Examination of ovary development in the ray floret showed that a mature ovule was formed, but fertilization did not occur. In advanced developmental stages, the capitulum showed proliferation of the endothelium, degeneration of the embryo sac, and all harvested cypselae had aborted seeds. Problems found in pollen viability and aborted cypselae could be the result of a history of vegetative propagation in the domestication process.
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina. ibanezmariasilvina@gmail.com.|Facultad de Ciencias Naturales, Instituto de Ecología Regional (IER), Universidad Nacional de Tucumán, C.C. 34, 4107, Yerba Buena, Tucumán, Argentina. ibanezmariasilvina@gmail.com.|Inta Balcarce, Ruta 226Km 73.5, ZIP 7620, Buenos Aires, Argentina. ibanezmariasilvina@gmail.com.
authors.forename: M S
authors.initials: MS
authors.lastname: Ibañez
authors.affiliation: Instituto de Morfología Vegetal, Fundación Miguel Lillo, Miguel Lillo 251, T4000INI, San Miguel de Tucumán, Tucumán, Argentina.
authors.forename: M I
authors.initials: MI
authors.lastname: Mercado
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.|PROIMI-Biotecnología CONICET, Av. Belgrano y Pasaje Caseros, T4001MBV, San Miguel de Tucumán, Tucumán, Argentina.|Cátedra de Biología Vegetal, Facultad Ciencias Naturales e Instituto Miguel Lillo, UNT, Miguel Lillo 251, T4000INI, San Miguel de Tucumán, Tucumán, Argentina.
authors.forename: M V
authors.initials: MV
authors.lastname: Coll Aráoz
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.|Facultad de Ciencias Naturales, Instituto de Ecología Regional (IER), Universidad Nacional de Tucumán, C.C. 34, 4107, Yerba Buena, Tucumán, Argentina.
authors.forename: M L
authors.initials: ML
authors.lastname: Zannier
authors.affiliation: Facultad de Ciencias Naturales, Instituto de Ecología Regional (IER), Universidad Nacional de Tucumán, C.C. 34, 4107, Yerba Buena, Tucumán, Argentina.|Cátedra de Biología Vegetal, Facultad Ciencias Naturales e Instituto Miguel Lillo, UNT, Miguel Lillo 251, T4000INI, San Miguel de Tucumán, Tucumán, Argentina.
authors.forename: A
authors.initials: A
authors.lastname: Grau
authors.affiliation: Instituto de Morfología Vegetal, Fundación Miguel Lillo, Miguel Lillo 251, T4000INI, San Miguel de Tucumán, Tucumán, Argentina.
authors.forename: G I
authors.initials: GI
authors.lastname: Ponessa
mesh_terms: D001118:Argentina; D019659:Asteraceae / Q000033:anatomy & histology / Q000254:growth & development* / Q000502:physiology; D035264:Flowers / Q000033:anatomy & histology / Q000254:growth & development*; D012098:Reproduction
keywords: Anatomy; Capitulum; Morphology; Reproductive organs; Smallanthus sonchifolius; Yacon