Inflorescence dimorphism, heterodichogamy and thrips pollination in Platycarya strobilacea (Juglandaceae)

Abstract

Background and AimsUnlike other taxa in Juglandaceae or in closely related families, which are anemophilous, Platycarya strobilacea has been suggested to be entomophilous. In Juglandaceae, Juglans and Carya show heterodichogamy, a reproductive strategy in which two morphs coexist in a population and undergo synchronous reciprocal sex changes. However, there has been no study focusing on heterodichogamy in the other six or seven genera, including Platycarya.MethodsInflorescence architecture, sexual expression and pollination biology were examined in a P. strobilacea population in Japan. Flowering phenology was monitored daily for 24 trees in 2008 and 27 in 2009. Flower visitors and inhabitants were recorded or collected from different sexes and stages.Key resultsThe population of P. strobilacea showed heterodichogamous phenology with protogynous and duodichogamous–protandrous morphs. This dimorphism in dichogamy was associated with distinct inflorescence morphologies. Thrips pollination was suggested by the frequent presence of thrips with attached pollen grains, the scarcity of other insect visitors, the synchronicity of thrips number in male spikes with the maturation of female flowers, and morphological characters shared with previously reported thrips-pollinated plants. Male spikes went through two consecutive stages: bright yellow and strong-scented M1 stage, and brownish and little-scented M2 stage. The latter contained more thrips, synchronized better with the receptive stage of female flowers of the reciprocal morph and is probably the main period of pollen export.Conclusions Platycarya strobilaceais heterodichogamous and thrips-pollinated, both of which are relatively rare conditions in angiosperms. In male spikes of P. strobilacea, there is probably a temporal decoupling of pollinator attraction and pollen export.

Heterodichogamy, Pollen Viability, and Seed Set in a Population of Polyploidy Cyclocarya Paliurus (Batal) Iljinskaja (Juglandaceae)

“…We found that unisexuality is a temporary trait based on the reduction of the ratio of M and F types with the maturation of the stand (Table 2). Similar findings were reported in J. ailanthifolia and J. mandshurica [9,29]. Researchers believe that the unisexual trait (F and/or M) is an environmental and/or nutrient (young age) response phenotype rather than a separate morph [9,24,25].…”

“…Labile sex expression was documented in some heterodichogamous trees across years, like in Acer pseudoplatanus [24,28]. It is reported that the sexual phenotype changed mainly from unisexual to the monoecious type, with few or no changes between PA and PG [8,9]. We found that unisexuality is a temporary trait based on the reduction of the ratio of M and F types with the maturation of the stand (Table 2).…”

“…Hitherto, plants with heterodichogamy have been documented in 13 families and 21 genera of flowering plants [8,9]. Heterodichogamy is particular found in Juglandaceae genera, including Juglans, Carya, Peterocarya, Platycarya, and Cyclocarya [1,9,10].…”

“…Hitherto, plants with heterodichogamy have been documented in 13 families and 21 genera of flowering plants [8,9]. Heterodichogamy is particular found in Juglandaceae genera, including Juglans, Carya, Peterocarya, Platycarya, and Cyclocarya [1,9,10]. Renner [1] reported that about half of the heterodichogamous taxa are self-incompatible, but the Juglandaceae family is completely self-compatible [6,7].…”

Estudos estruturais como subsídio à taxonomia de Simaba Aubl.(Simaroubaceae)

“…A maioria destas espécies documentadas é economicamente visada ou amplamente cultivada, cenário este que facilita a detecção desta forma de dimorfismo. A dificuldade no estudo para verificar a mudança sexual em populações de plantas dimórficas, que requerem monitoramento em longo prazo, além da mudança de sexo poder variar muito em tempo ocorrendo do dia para a noite ou uma única vez durante todo o período de floração, evidencia a necessidade de mais estudos sobre os sistemas sexuais de populações que apresentam variações funcionais nos sistemas reprodutivos (Renner 2001;Renner et al 2007;Wang et al 2012;Fukuhara & Tokumaru 2013). Estudos com essas abordagens devem ser realizados com espécies de Simaba.…”