Pollen morphology of selected species of the subfamily Bombacoideae (Malvaceae sensu lato)
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We analyzed the pollen grains of 11 species within the subfamily Bombacoideae. The pollen grains were acetolyzed, after which they were analyzed and photographed under light microscopy. Unacetolyzed pollen grains were analyzed and photomicrographed under scanning electron microscopy. We studied pollen characters such as shape, size, exine ornamentation and aperture type. The species were separated by a pollen key, which considers the presence or absence of "calotte" in the pollen grains. This attribute separated Ceiba and Eriotheca from the other genera. Some species are differentiated by specific characters: in Bombacopsis glabra and B. stenopetala, the sexine is rugulate or "vermiculate" with isolated pilate elements; in B. calophylla, the pollen grains are sinu-aperturate; Ceiba speciosa show atypical, duplicolumellate sexine; C. erianthos is the only species with 5-colporate pollen grains and a pentagonal amb; in Pachira aquatica the reticulum has muri with spiculaspinulose muri ("reticulum cristate"). The variation in the pollen morphology confirms the eurypalynous status of the genera studied here.Keywords:
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Diversity of pollen apertures in 35 families of the ranalean complex is compared through a series of representative scanning electronmicrographs, and the evolution of pollen aperture types in primitive angiosperms is outlined. A classification of pollen apertures found in the ranalean complex is presented, and ten basic aperture types are recognized: anasulcate, anatrichotomosulcate, zonasulculate, anaulcerate, catasulcate‐cataulcerate, inaperturate, disulculate‐diulculate, forate, colpate, and porate. Evidence is adduced for the primitive (ancestral) status of anasulcate pollen, and transitional stages in the evolution of other pollen aperture types in the ranalean complex are examined. From an early stock of ranalean angiosperms with anasulcate pollen, there appears to have been development of a number of interesting but evolutionally dead‐end lines, represented among others by zonasulculate, anaulcerate, and catasulcate‐cataulcerate pollen types. The most important evolutionary trend in early angiosperm pollen seems to have been the development of inaperturate pollen grains in many families of primitive angiosperms, from which there was a second major radiation of aperture types, including evolution of disulculate and forate pollen. Comparative study of pollen apertures observed in living primitive angiosperms suggests a de novo origin of the uniquely angiospermous (dicotyledonous) colpate pollen type from such inaperturate pollen.
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Citrus is one of the most wide cultivated fruits in the world. Pollen morphology of citrus is one of the most important characteristics used in classification and reproductive biology studies. In this paper we reviewed the progress of palynological characters including pollen size, aperture, and exine ornamentation. Pollen grains of Citrus are usually circular in shape with 4-colporate aperture, and elliptical equatorial view. The exine thickness ranges from 1-3 μm. The size of grains is small to medium with polar axis ranging from 22-45 μm. This basic knowledge on citrus pollen morphology provides a fundamental information for understanding the development and fertility of citrus pollen.
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Helicteres genus, Malvaceae, has pantropical distribution, encompasses about 60 species, 31 of them found in Brazil.Species belonging to this genus are used for treatment of various diseases and aroused scientific interest in search for bioactive compounds present in these plants.In this context, this review aims to provide a complete and concise overview of scientific advances in phytochemical and pharmacological studies of these species and their use by folk medicine.The presented data were collected from scientific databases, 'Web of Science', 'Scifinder', 'Pubmed', 'Sciencedirect', and 'Google Scholar', using the keyword 'Helicteres'.The species H. isora and H. angustifolia, found in Asia, are the most explored scientifically, whereas studies of species of this genus found in Americas are still rare, being possible to highlight studies carried out in Brazil with H. velutina and H. eichleri.About 149 compounds were isolated and characterized in the genus, being emphasized terpenoids, flavonoids and lignoids.These species have demonstrated various pharmacological properties in vitro and in vivo, incluinding insecticide, antidiabetic, antitumor and hepatoprotective activities.The presented data show the importance of studies carried out isolating bioactive compounds from this genus that may be used in several diseases' treatment or/as prototypes to development of new drugs.
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Diversity of pollen apertures in 35 families of the ranalean complex is compared through a series of representative scanning electronmicrographs, and the evolution of pollen aperture types in primitive angiosperms is outlined. A classification of pollen apertures found in the ranalean complex is presented, and ten basic aperture types are recognized: anasulcate, anatrichotomosulcate, zonasulculate, anaulcerate, catasulcate-cataulcerate, inaperturate, disulculate-diulculate, forate, colpate, and porate. Evidence is adduced for the primitive (ancestral) status of anasulcate pollen, and transitional stages in the evolution of other pollen aperture types in the ranalean complex are examined. From an early stock of ranalean angiosperms with anasulcate pollen, there appears to have been development of a number of interesting but evolutionally dead-end lines, represented among others by zonasulculate, anaulcerate, and catasulcate-cataulcerate pollen types. The most important evolutionary trend in early angiosperm pollen seems to have been the development of inaperturate pollen grains in many families of primitive angiosperms, from which there was a second major radiation of aperture types, including evolution of disulculate and forate pollen. Comparative study of pollen apertures observed in living primitive angiosperms suggests a de novo origin of the uniquely angiospermous (dicotyledonous) colpate pollen type from such inaperturate pollen.
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