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There are few studies focused on spore and pollen clumps in paleopalynological samples, and these are only reports from the Northern Hemisphere. These aggregates may be of animal or floral origin. The goal of this contribution is to provide the first detailed study of spore and pollen clumps from the Southern Hemisphere, and to discuss their possible origin, botanical affinities, and pollination modes, based on their morphological characteristics, preservation and comparison with putative living representatives. Three fern spore clumps and 18 angiosperm pollen clumps were recognized in Maastrichtian-Danian La Colonia Formation sediments that outcrop at Chubut Province, Patagonia, Argentina. Most clumps are monospecific and composed of undamaged elements but some of them have two types of spore/pollen with corroded and/or fragmented exines. These findings represent the most diverse and abundant record of fern and angiosperm clumps from the Late Cretaceous and early Paleocene so far known from South America and the Southern Hemisphere. These results are indicative of the need for comprehensive large-scale studies on pollination of modern taxa and careful processing of palynological samples to lessen the already large bias in paleopalynological interpretations. The paucity of information on clumps in the fossil record has impaired our comprehension of dispersion/pollination in deep time. Keywords Floral origin * Coprolites * Monospecific clumps * Pollination modes Hay pocos estudios enfocados en agregados de esporas y polen procedentes de muestras palinologicas, y estos han sido reportados unicamente en el Hemisferio Norte. Estos agregados pueden ser de origen animal o floral. El objetivo de esta contribucion es proveer el primer estudio detallado de agregados de esporas y polen del Hemisferio Sur, y discutir sus posibles origenes, afinidades botanicas y modos de polinizacion, basados en sus caracteristicas morfologicas, preservacion y comparacion con posibles analogos modernos. Tres agregados de esporas de helechos y 18 de polen de angiospermas fueron reconocidos en los sedimentos del Maastrichtiano-Daniano de la Formacion La Colonia, aflorantes en la Provincia de Chubut, Patagonia, Argentina. La mayoria de los agregados son monoespecificos y estan compuestos por elementos en general bien preservados, aunque algunos tienen dos tipos de esporas/polen con exinas corroidas y/o fragmentadas. Estos hallazgos constituyen el registro mas diverso y abundante de agregados esporopolinicos del Cretacico Tardio y Paleoceno temprano de Sudamerica y del Hemisferio Sur. Los resultados de este trabajo indican la necesidad de realizar estudios exhaustivos a gran escala sobre polinizacion en taxones modernos y de desarrollar nuevas tecnicas palinologicas menos destructivas que permitan recuperar los agregados de las paleoasociaciones. Claramente, la escasez de informacion sobre agregados polinicos en el registro fosil afecta nuestra interpretacion acerca de la dispersion/polinizacion y su evolucion en el tiempo. Palabras clave Origen floral * Coprolitos * Agregados monoespecificos * Modos de polinizacion, Introduction Pollen and spores have major roles in plant sexual reproduction as they are fundamental to maintaining plant populations and successfully colonizing of new habitats. Floral and pollen traits are [...]

Cycads (Cycadales) are among the most ancient lineages of extant seed-bearing plants and are the most threatened plant order on Earth, with circa 75% of the 356 accepted species endangered or threatened with extinction. Zamia is the most species-rich (81 spp.) and widely distributed cycad genus in the Americas, notable for its morphological and ecological diversity. Across the genus, there appears to be a high degree of convergence among macromorphological traits, with many characters that are useful for species identification proving uninformative for elucidating relationships among species. However, it remains unknown whether anatomical variation in leaflet structure corresponds with phylogenetic or geographic patterns, as has been investigated in Dioon and Cycas. Here, we present a broad comparative survey of leaflet anatomy across Zamia species with the goals of describing anatomical diversity and uncovering diagnostic characters for resolved clades. Anatomical characters were scored based on the literature and newly prepared sections of leaflets from 20 Zamia species plus the outgroup species Microcycas calocoma. The resulting matrix covers 39 Zamia species representing all five major clades and spanning the geographic distribution of the genus. Anatomical characters scored from leaflet sections were mapped onto a previously published phylogeny and evaluated for their phylogenetic signal. Most anatomical characters examined are not diagnostic for clades, but newly reported mesophyll sclereids may be unique to one large lineage. Given the widespread incongruence between phylogenetic relationships and the distribution of anatomical traits, we tested the relationship between anatomical characters and environmental signals but did not uncover significant correlations between anatomy and ecology. While further work is required to elucidate the evolutionary history of anatomical characters in this genus, this research improves our understanding of micromorphological character evolution, anatomical diversity, and phylogenetic relationships within this highly threatened lineage of plants. Keywords Cycads * Neotropics * Gyrrmosperms * Sclereids * Biogeography * Hypodermis, Introduction Zamia L. is the second-largest genus in the Cycadales, and the most morphologically, ecologically, and karyologically diverse in the order (Caputo et al., 1996; Jones, 2002; Norstog, 1981; Stevenson, [...]

The Plant Ontology (PO) is a community resource consisting of standardized terms, definitions, and logical relations describing plant structures and development stages, augmented by a large database of annotations from genomic and phenomic studies. This paper describes the structure of the ontology and the design principles we used in constructing PO terms for plant development stages. It also provides details of the methodology and rationale behind our revision and expansion of the PO to cover development stages for all plants, particularly the land plants (bryophytes through angiosperms). As a case study to illustrate the general approach, we examine variation in gene expression across embryo development stages in Arabidopsis and maize, demonstrating how the PO can be used to compare patterns of expression across stages and in developmentally different species. Although many genes appear to be active throughout embryo development, we identified a small set of uniquely expressed genes for each stage of embryo development and also between the two species. Evaluating the different sets of genes expressed during embryo development in Arabidopsis or maize may inform future studies of the divergent developmental pathways observed in monocotyledonous versus dicotyledonous species. The PO and its annotation database (http://www.planteome.org) make plant data for any species more discoverable and accessible through common formats, thus providing support for applications in plant pathology, image analysis, and comparative development and evolution.

Premise Methods Results Conclusions Fossil infructescences and isolated fruits with characters of Malvoideae, a subfamily of Malvaceae (mallow family), were collected from early Eocene sediments in Chubut, Argentina. The main goals of this research are to describe and place these fossils systematically, and to explore their biogeographical implications.Fossils were collected at the Laguna del Hunco site, Huitrera Formation, Chubut, Patagonia, Argentina. They were prepared, photographed, and compared with extant and fossil infructescences and fruits of various families using herbarium material and literature.The infructescences are panicles with alternate arrangement of fruits. They bear the fruits on short pedicels that are subtended by a bract; the fruits display an infracarpelar disk and split to the base into five ovate sections interpreted as mericarps. Each mericarp is characterized by an acute apex and the presence of a longitudinal ridge. The isolated fruits show the same features as those on the infructescences. The fossils share unique features with members of the cosmopolitan family Malvaceae, subfamily Malvoideae.The fossils have a unique combination of characters that does not conform to any previously described genus, justifying the erection of a new genus and species, Uiher karuen. This new taxon constitutes the first known Malvoideae reproductive fossils of the Southern Hemisphere, expanding the distribution of Malvoideae during the early Eocene. [ABSTRACT FROM AUTHOR]