Developmental morphology of the flower of Anaphyllopsis americana and its relevance to our understanding of basal Araceae

Abstract

The inflorescence of Anaphyllopsis americana (Engler) A. Hay consists of more than 100 flowers arranged in recognizable spirals. Each flower has four broad tepals enclosing four stamens that are not visible prior to anthesis. The unilocular ovary contains one ovule and bears a discoid stigma. The floral primordia are first initiated on the upper portion of the inflorescence. At an early stage during their development, the floral primordia have a circular shape. Two lateral tepals are initiated nearly simultaneously followed by two median tepals. After their initiation, each stamen is associated with a tepal of the same radius; the two lateral stamens are initiated first, directly opposite to the lateral tepals. The unilocular nature of the ovary is clearly visible during the early stages of development of the gynoecium. At dehiscence, anther wall raphides are present in anther locules and are mixed with pollen. The mode of floral development observed in Anaphyllopsis is similar to that reported for Anthurium jenmanii Engl. However, this similarity in mode of development may be linked to structural constraints rather than phylogenetic relationships. The presence of a few pentamerous flowers in the inflorescence of Anaphyllopsis suggests a possible relationship with Dracontium. This would be in accordance with recent molecular studies showing that Anaphyllopsis and Dracontium are closely related.Résumé : L'inflorescence de l'Anaphyllopsis americana (Engler) A. Hay comporte plus de cent fleurs arrangées en spirale évidente. Chaque fleur possède quatre larges tépales entourant 4 étamines qui demeurent invisibles jusqu'à l'anthèse. L'ovaire uniloculaire contient un ovule et porte un stigmate discoïde. Les primordiums floraux apparaissent d'abord sur la partie supérieure de l'inflorescence. Au début de leur développement, les primordiums floraux montrent une forme circulaire. Deux tépales latéraux amorcent leur formation presque simultanément, suivis de deux tépales médians. Après leur initiation, chaque étamine s'associe à un tépale de même rayon; les deux étamines latérales se forment d'abord, en position directement opposée aux tépales latéraux. On identifie facilement la nature uniloculaire de l'ovaire au cours des premiers stades du développement du gynécée. À la déhiscence, on observe les raphides des parois des anthères dans les loges des anthères, se mélangeant au pollen. Le mode de développement floral observé chez l'Anaphyllopsis correspond à celui dé-crit pour l'Anthurium jenmanii Engl. Cependant, cette similarité du mode de développement peut être liée à des contraintes structurales plutôt qu'à des relations phylogénétiques. La présence de quelques fleurs pentamères dans l'inflorescence suggère une relation possible aux Dracontium. Ceci correspondrait avec les récentes études moléculaires montrant que les Anaphyllopsis et les Draconium sont étroitement apparentés.

Gynoecial ontogeny of Anthurium: contributions for floral developmental studies in Araceae (Alismatales)

“…The majority of studies on floral ontogeny in Araceae have been documented in genera with unisexual, non-perigoniate flowers (e.g., Boubes and Barabé 1997;Barabé and Lacroix 2001, 2008aBarabé et al 2002aBarabé et al , 2002bBarabé et al , 2012, and few studies have investigated bisexual perigoniate flowers (Buzgo 2001;Barabé and Lacroix 2008b;Barabé et al 2011). In the present study, despite the emphasis on gynoecial ontogeny, we took into account the importance of carpel formation and its relation to the growth of the other flower parts.…”

“…One important aspect is the formation of an inferior ovary in the basal groups of the family (Barabé et al 1987) and the morphological variation of the sterile flowers of Aroideae Lacroix 2001, 2002;Barabé et al 2002aBarabé et al , 2002bBarabé et al , 2012. In addition, the increase in floral merosity in Lasioideae and its relation to developmental processes (Barabé and Lacroix 2008a;Barabé et al 2011) and the occurrence of atypical flowers in the family are also important aspects (Barabé and Lacroix 2014). These studies have widened our knowledge on floral morphology, particularly for genera in which the observations of reproductive organs are limited to the stereomicroscopy of herbarium specimens.…”

Durianology, discovery, and saltation — the evolution of aroids

“…The subfamily Lasioideae, comprising the 10 genera of the relict pantropical tribe Lasieae, is particularly interesting as the subfamily of bisexual-floreted aroids in which the number of floral parts per floret is the least canalised. The plants are generally rather rare and it can be difficult to obtain sufficient material to study them developmentally, but Denis Barabé and colleagues have analysed spadix and floret development in a species of each of three of the four neotropical genera forming the New World lasioid clade in the molecular analysis of Cusimano et al (2011): Anaphyllopsis americana (Barabé & Lacroix, 2008), Dracontium polyphyllum (Poisson & Barabé, 2011), and Urospatha sagittifolia (Rudge) Schott (Barabé et al, 2011); only Dracontioides is lacking. In their publication on Anaphyllopsis, Barabé & Lacroix (2008) concluded that it might be hypothesised that the tetrameous flowers such as predominate in Anaphyllopsis may be derived from an ancestor with polymerous flowers such as in Dracontium.…”

Patterns of angiospermy development before carpel sealing across living angiosperms: diversity, and morphological and systematic aspects

“…Also in other Araceae the ovules are covered from the beginning, as in Anaphyllopsis (Engl.) A.Hay (Barabé & Lacroix, ), Philodendron Schott (Barabé, Lacroix & Jeune, ; Barabé & Lacroix, ), Schismatoglottis Zoll. & Moritizi in H.Zollinger (Barabé et al ., ) and others.…”