Handbook of palynology

Plant Breeding Systems.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1096-0031.2008.00212.x

Plant Systematics: A Phylogenetic Approach

Nectar production and presentation

The construction of classifications, as well as the understanding of biological diversity, depends upon a careful comparison of attributes of the organisms studied (Stuessy, 1990). It is widely known that data from diverse sources showing differences from taxon to taxon are of systematic significance. During the 20th century, systematists have emphasized that their discipline involves a synthesis of all knowledge (Stevens, 1994) or, in other words, the variation of as many relevant characters as possible should be incorporated into the natural system to be constructed. The extent to which particular characters are constant or labile will determine their usefulness to systematics. In general, more conservative characters will be valuable in defining families and orders, whereas more labile characters may be useful at the generic and specific levels (Webb, 1984). There is no doubt that floral characters are among the most used in the classification of flowering plants. At the same time, they constitute essential features in diagnostic keys to taxa in both taxonomic treatments and Floras (Cronquist, 1981, 1988).

A systematic survey of floral nectaries

The aim of the present study is to provide detailed morphological descriptions of the seed coat in 10 species of Oxalis from Buenos Aires Province, Argentina, using light microscopy and scanning electron microscopy. The seed is ovate and brown, and its surface is smooth. Oxalis has a mechanism of spermobolia by which a part of the seed coat is detached by the rupture of cells, leaving exposed a layer of opened cells, generally with oxalate crystals. This new coat surface has different characteristics in the species studied in this work. Three types are recognized, mostly on the basis of anatomical and ultrastructural characteristics of the seed coat. The species grouped in each of the 3 types of seeds belong to different sections of the genus; thus, the seed morphology could be of taxonomic value for the genus Oxalis.

Morphology of the seed coat of Oxalis spp. from Buenos Aires Province (Argentina)

Ovule morphology, megasporogenesis and megagametogenesis of ten species of Oxalis were examined. The ovule is anatropous, bitegmic and the integuments form a zig-zag micropyle. The type of female gametophyte development is variable in the studied species. The majority of them have a monosporic Polygonum-type female gametophyte. Two of the studied species show binucleate dyad members, so they have a bisporic Allium-type female gametophyte. Only O. articulata follows tetrasporic Adoxa-type development of the megagametophyte. This is the first report of a tetrasporic female gametophyte in Oxalidaceae. The endosperm is nuclear, and development of the embryo corresponds to the Solanad type.

/pdf/megasporogenesis-and-megagametophyte-development-in-ten-2kejc82zsh.pdf

Megasporogenesis and Megagametophyte Development in Ten Species of Oxalis

Polybia scutellaris (White, 1841) is a social wasp of biological interest for its role as pollinator and maybe as biological control agent of sanitary and agricultural pests. This study examines the digestive tract contents of the larvae of P. scutellaris from four nests in Magdalena (Buenos Aires province, Argentina). Contents included both animal (arthropod parts) and plant (pollen, leaf and fruit epidermis) parts. The pollen content analysis showed that the wasps visited 19 different taxa of plants during the last active period of the colony before the nests had been collected. The range of sources used by P. scutellaris allows us characterizing the species as a generalist flower visitor. Wasps visited both native and exotic plants located nearby the nest. Most of the epidermal plant remains found in the larval digestive tract belonged to Malvaceae, a family not exploited by the studied colonies as pollen source.

http://www.scielo.br/pdf/rbent/v55n2/AOP2111.pdf

Analysis of digestive tract content of the larvae of Polybia scutellaris (White) (Hymenoptera, Vespidae)

Chloroplast dimorphism in leaves of Cabomba caroliniana (Cabombaceae)

Geraldina Alicia RICHARD*, María Carolina CERINO, Beatriz Gloria GALATI, Eliana De Luján EXNER, José Francisco PENSIERO Department of Plant Biology, Faculty of Agricultural Sciences, National University of the Littoral (Universidad Nacional del Litoral, in Spanish), Esperanza, Argentina National Council of Scientific and Technical Research, Buenos Aires, Argentina Department of Natural Resources and Environment, Faculty of Agriculture, National University of Buenos Aires (Universidad Nacional de Buenos Aires, in Spanish), Buenos Aires, Argentina

Beatriz G. Galati

Papers

Morphology of the seed coat of Oxalis spp. from Buenos Aires Province (Argentina)

Megasporogenesis and Megagametophyte Development in Ten Species of Oxalis

Analysis of digestive tract content of the larvae of Polybia scutellaris (White) (Hymenoptera, Vespidae)

Chloroplast dimorphism in leaves of Cabomba caroliniana (Cabombaceae)

Embryological studies on Trichloris (Poaceae, Chloridoideae)