Abstract
Data of six studied Neotropical Anaxagorea species are analyzed and discussed with respect to the population structure, flowering phenology, flower morphology, anthesis, scent emission, thermogenesis, floral visitors, breeding system, fruit-set and seed dispersal. The probably reason for the patchy distribution of small populations of Anaxagorea species within lowland tropical forests is given. A novel explanation of the functional significance of ruminate endosperm is presented. Flowering of the species follows either the annual or the continuous flowering pattern. All studied species have diurnal, two-day lasting, protogynous anthesis; several species have thermogenic flowers. Self-compatibility appears to be the prevailing reproductive system in the genus. However, there is a strong tendency for effecting cross-pollination. Floral scent of Anaxagorea species contains fruit-like components, and the pollinators, primarily Nitidulidae (Colopterus spp.) are attracted by deceit. Strong scenting pollination chambers occur also in most other cantharophilous Annonaceae. Novel floral developments are apparent mainly in fly-, cockroach- and bee-pollinated Annonaceae, which have patterns different from cantharophilous species and exhibit open flowers with reflexed petals, which allow their pollinators to reach and touch the reproductive organs.
Highlights
With about 2300-2500 species, the family Annonaceae is the most species-rich group of the Magnoliales and, together with the Piperaceae (Piperales), Lauraceae (Laurales) and Araceae (Alismatales, basal monocots), the Annonaceae belong to the largest families of the basal angiosperms (e.g. Bremer et al 2009; Smith et al 2010; Zeng et al 2014)
The monophyly of Annonaceae and the sister group relationship between Anaxagorea and the remaining Annonaceae was supported in several analyses (Chatrou et al 2012). e basal position of Anaxagorea in Annonaceae is indicated by several distinctive, putatively ancestral morphological character states, that are found in the closest outgroups of Annonaceae, especially in Eupomatia (Eupomatiaceae), Degeneria (Degeneriaceae) and Galbulimima (Himantandraceae), for example, the stamens are laminar, there are inner staminodes, the pollen is granular and monosulcate, and species have an adaxial plate of vascular tissue in the leaf midrib (Maas & Westra 1984; 1985; Doyle & Le omas 1994; 1996; Scharaschkin & Doyle 2005; 2006)
In most Anaxagorea species pistillate and staminate stage owers can occur at the same time on one individual tree. is condition would enable geitonogamous pollination
Summary
With about 2300-2500 species, the family Annonaceae is the most species-rich group of the Magnoliales and, together with the Piperaceae (Piperales), Lauraceae (Laurales) and Araceae (Alismatales, basal monocots), the Annonaceae belong to the largest families of the basal angiosperms (e.g. Bremer et al 2009; Smith et al 2010; Zeng et al 2014). ABSTRACT Data of six studied Neotropical Anaxagorea species are analyzed and discussed with respect to the population structure, owering phenology, ower morphology, anthesis, scent emission, thermogenesis, oral visitors, breeding system, fruit-set and seed dispersal.
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