Anatomy and development of the reproductive units of Mapania pycnostachya and Hypolytrum schraderianum (Mapanioideae, Cyperaceae)

Abstract

The typical mapaniid reproductive unit, which comprises several bracts, stamens and a gynoecium, may be interpreted as a single flower. Although developmental studies suggest that the mapaniid reproductive units are inflorescences, the units in species such as Hypolytrum schraderianum Nees are much reduced and strongly resemble a single flower. Therefore, an anatomical and developmental study of the reproductive units of Mapania pycnostachya (Benth.) T.Koyama and H. schraderianum was conducted to better understand their structure. In both species, two lateral bracts (prophyll-like units) are the first to emerge, followed by staminal and gynoecial primordia. The reproductive units of M. pycnostachya have two inner bracts (leaf-like structures) that initiate after the stamens. In H. schraderianum, they are absent. In both species, the reproductive units have spiral phyllotaxy and staminal traces that join the vascular system of the reproductive-unit axis at different levels. The vasculature pattern of these units differs from the cyperoid flowers. On the basis of these results, it is inferred that the reproductive units of both species are inflorescences, composed of unisexual flowers. It is also inferred that this structure is the general pattern for Mapanioideae and that loss of male flowers and inner bracts has occurred during evolution of the subfamily.

Flower and Spikelet Construction in Rapateaceae (Poales)

“…In most Poales, the term "spikelet" is used instead of "spike" to highlight the arrangement of small spikelets in complex inflorescences. Typical spikelets of Poales lack a terminal flower (Eiten, 1976;Vrijdaghs et al, 2010;Kellogg, 2015), unless the problematic reproductive structures of Cyperaceae-Mapanioideae are interpreted as partial inflorescences (Richards et al, 2006;Vrijdaghs et al, 2006;Prychid and Bruhl, 2013;Monteiro et al, 2016). In the biotically pollinated families Bromeliaceae, Eriocaulaceae, and Xyridaceae, the inflorescences are racemose and lack a terminal flower (Stützel, 1982;De Sousa et al, 2008;Remizowa et al, 2012;Nogueira et al, 2017Nogueira et al, , 2021.…”

Root, rhizome and scape anatomy of Amazonian species of Mapania Aubl. (Mapanioideae, Cyperaceae) and its taxonomic and ecological significance

“…; Monteiro et al. ). The comparative anatomy of leaf organs helped to characterize Mapania and to distinguish it from Hypolytrum , as a hypodermis is found only in leaf blades of the former (Alves et al.…”

“…So far, few anatomical studies have been carried out on Mapania, particularly on the vegetative organs of some species or the reproductive units of M. pycnostachya (Koyama 1966;Metcalfe 1971;Alves et al 2002;Silva et al 2014;Monteiro et al 2016). The comparative anatomy of leaf organs helped to characterize Mapania and to distinguish it from Hypolytrum, as a hypodermis is found only in leaf blades of the former (Alves et al 2002).…”

Desenvolvimento, anatomia e evolução de caracteres florais em Cyperaceae (Poales)

“…Considering the patterns on floral development, in Cyperoideae despite the wide diversity in floral morphology, the floral development was reported as following a general scirpoid ontogenetic pattern, in which the first organs to appear are the stamen primordia, followed by gynoecium primordium and later on, if present, perianth parts (Vrijdaghs et al, 2009). For Mapanioideae, developmental studies mainly focus on the debated nature of the spicoids as flowers or inflorescences (Richards et al, 2006;Prychid & Bruhl, 2013;Monteiro et al, 2016), lacking a comparative approach among the development processes in such species. Taking that in account, it led to the third chapter of the thesis:…”

“…3. Spicoid ontogeny in Diplasia (Cyperaceae): an approach on the developmental processes operating in Mapanioideae spicoids -This chapter has a complete ontogenetic analysis of the spicoid of the monotypic genus Diplasia and compare these data with other developmental studies for Mapanioideae (Richards et al, 2006;Prychid & Bruhl, 2013;Monteiro et al, 2016) in order to elucidate the variability of developmental features and their influence in the final morphology of Mapanioideae spicoids. Furthermore, we discuss evidence that may help to interpret Diplasia spicoid as a flower or inflorescence.…”