Anatomy of the reproductive structures of Stenanona flagelliflora (Annonaceae)

Abstract

The genus Stenanona comprises 15 species distributed from Mexico to Colombia. Stenanona flagelliflora is the only species in which the reproductive structures are found on the flagellum, a unique phenomenon in the flora of Mexico. Our objective is to recognize and describe anatomical features of flowers and fruits that contribute to the systematics of the species. We collected floral buds in three different stages of development (buds I, II, and III), flowers at anthesis, and immature and mature fruits in the ecological reserve of the ejido Adolfo López Mateos, Catemaco, Veracruz, Mexico; the samples were fixed in formalin-acetic acid-alcohol (FAA), cut, stained, and mounted using conventional histological techniques. The receptacle has numerous vascular bundles distributed in two cylinders: the perianth is trimerous; it has 32 stamens arranged in four whorls; the anthers have a deltoidshaped extension of connective tissue; the gynoecium has 5-7 free carpels. Bud II showed a bitegmic and crassinucellate ovule with four layers of the outer integument and two of the inner integument, an ovary with trichomes on the outer epidermis and reduced style, and anthers in different stages of development. Bud III showed epidermis with bulliform cells in the style and stigma. The fruit is of berry type; the ripe fruit shows longitudinal series of fibers across the mesocarp. The endosperm is ruminate; the embryo is small and undifferentiated. These features are common in the Annonaceae family; however, the number of integumentary layers in the ovule and the presence of papillae on the style and stigma are novel characters.

Triploid frequency of sexual hybridization and pollen and ovary development in mandarins

“…The general characteristics the 'Fortune' mandarin observed in the development of the anther and the male gametophyte are quite similar to those observed in most angiosperms (Velázquez et al 2016). Within the anthers, the sporogenic cells differentiated and performed meiosis to produce microspores, which passed through mitosis and formed male gametophytes or pollen grains.…”

“…Most studies performed on the floral development of plants have focused on the development of the male gametophyte (Velázquez et al 2016). It is difficult to analyze the female gametophyte, especially in citrus.…”

Morfología del fruto y semilla, y tratamientos pregerminativos de <i>Annona reticulata</i>

“…El endospermo ruminado y el embrión basal pequeño (de 1/4) son característicos del género Annona (Niembro 1988, Svoma 1998. El tejido ruminado es resultado de pliegues formados por fibras de la mesotesta y endotesta, peculiar en la familia Annonaceae (Velázquez et al 2016).…”

Desmopsis terriflora, an extraordinary new species of Annonaceae with flagelliflory

“…Very little is known about the origin and evolution of flagelliflory and about the ecological-evolutionary advantages that this condition provides to the species ( Couvreur 2009 ). Some studies have shown that in species with flagelliflory, the flowers have a very low diversity of floral visitors and that pollinators and dispersers are specific species ( Harrison et al 2012 ; Teichert et al 2012 ; Xicohténcatl-Lara et al 2016 ).…”

“…In Mesoamerica (southern Mexico and Central America), flagelliflory has been documented in just one species of Annonaceae restricted to the karst forests of southern Mexico: Stenanona flagelliflora T.Wendt & G.E.Schatz ( Schatz and Wendt 2004 ). This species, which belongs to a clade of Central American genera within the larger south east Asian tribe Miliuseae (subfamily Malmeoideae Chatrou et al 2012 ) is known from two allopatric localities in Veracruz, Mexico, one in the Uxpanapa-Chimalapas region and the other in the Los Tuxtlas region ( Schatz and Wendt 2004 ; Xicohténcatl-Lara et al 2016 ). Stenanona flagelliflora is a small tree up to 2 m tall, with all its inflorescences borne on woody and branched flagella up to 3 m long, which often have small leaves or leaves reduced to bracts ( Schatz and Wendt 2004 ).…”