Developmental and Structural Section
Corona-Vázquez, Tania , Andrés-Hernández, Rosa , Figueroa-Castro, Dulce , Campos-Villanueva, Álvaro .
Floral anatomy of Stenanona flagelliflora (Annonaceae), an endemic species from Mexico.
Stenanona flagelliflora (Annonaceae), is the only flagelliflorous species known in Mexico. The flagellum grows from the base of the stem, and the reproductive structures are produced on it. Because the species was recently described, there is a lack of knowledge on its biology. This study was conducted in order to describe the anatomy and development of the flowers. Reproductive structures from five different stages of development (Bud I, Bud II, Bud III, Flower I, and Flower II) were collected in "Los Tuxtlas" region, Veracruz, Mexico. Samples were placed in formaldheid : glacial acetic acid : alcohol and then were processed with conventional techniques for paraffin-embedded and safranin O-fast green staining. Bud I. It has three sepals; six petals; epidermis and hypodermis present only in the adaxial region; unicelular trichomes; compact parenchima; five to eigth vascular bundles; anthers with archesporic and esporogen tissues; apocarpic gynoecium with rectangular epidermis, external and internal hypodermis; ovary with mesophyll; embryo sac with a single mother cell; discoid stigmas with parenchima of irregular shape. Bud II. Anthers with distinguishable striated epidermis, tapetum, endothecium and pollen sacs. Pollen sacs differentially developed: basal whorl with in mature sacs; second whorl with tetrads; third whorl with nucleate microspores and, the fourth whorl with an apical expansion of the connective tissue under the stigma and with collapsed microspores. Bud III. Basal anthers with collapsed pollen, endothecium with squared, anticlinal cells and striated cuticle; second whorl with globose pollen. Ovary epidermis with abundant simple-trichomes. Flower I. Ovary with stipe; parietal placentation, a single anatropous ovule; internal region of the style with squared cells that continue down to the ovary cavity; stigma with a cleft in the medium region and striated cuticle. Flower II. Anthers with longitudinal dehiscence along the connective tissue. All floral organs with abundant lipid drops and pectic idioblasts. In comparison with other Annonaceae species, Stenanona flagelliflora always has a single ovule per ovary and shows an extension of connective tissue folded under the discoid stigma. Moreover, pollen grains are completely developed before the maturation of the megagametophyte.
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1 - Benemérita Universidad Autónoma de Puebla, Escuela de Biología, , Blvd. Valsequillo y Av. San Claudio, Edif. 112A,, Ciudad Universitaria, Col. San Manuel, Puebla, Puebla, 72570, México
2 - Universidad Nacional Autónoma de México, Estación de Biología Tropical "Los Tuxtlas", , Instituto de Biología, Km. 30 camino Catemaco-Montepío, A.P. 94, San Andrés Tuxtla, Veracruz, 95701, Mexico
Presentation Type: Poster:Posters for Sections
Location: Battelle South/Convention Center
Date: Monday, July 9th, 2012
Time: 5:30 PM