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Resumen Introducción: Los estudios sobre microsporogénesis, micromorfología y estructura de los granos de polen en Malvaceae son escasos. Objetivos: Describir el proceso de microsporogénesis y aspectos micromorfológicos de los granos de polen en A. rosea. Métodos: Se procesaron más de 30 andróforos de acuerdo con los protocolos estándar para incrustar y seccionar en parafina. Las secciones obtenidas se tiñeron con Azul de Safranina-Alcian, las anteras inmaduras y no fijadas se tiñeron con Azul de anilina. Se procesaron secciones de resina adicionales de los andróforos y se tiñeron con azul de toluidina. Se observaron secciones ultrafinas con microscopía electrónica de transmisión (MET). Para la observación con microscopía electrónica de barrido (MEB), el material se fijó y deshidrató en 2,2 dimetoxipropano, luego se secó hasta un punto crítico y se recubrieron con oro. Resultados: las anteras se diferencian de una masa celular en los extremos distales de los filamentos del estambre. La pared de la antera madura presenta una capa externa de células epidérmicas y una capa interna, el endotecio. Las células madre de microesporas se dividen por mitosis y luego experimentan meiosis para formar tétradas. El tapete es inicialmente celular y forma una sola capa de células y luego pierde integridad celular al invadir el lóculo de microsporangio, formando un periplasmodio. Durante la formación de la esporodermis, primero se deposita la exina y luego la intina. Para el momento de la liberación de los granos de polen, el tapete se ha degenerado por completo. Los granos de polen son pantoporados, apolares, con simetría radial, esferoidales, con espinas, báculas, gránulos y microgránulos. El téctum está perforado con fovéoleas dispuestas homogéneamente en toda la superficie y con polenkit. La exina es ancha (5-6 µm) y consta de una endexina gruesa de 3.5 a 4 µm y una ektexina fina (0.6-0.7 µm). La ultraestructura muestra columelas claramente definidas formando el infratéctum. Se aprecian tricomas nectaríferos unicelulares glandulares capitados (TG) cubriendo toda la superficie de los filamentos de los estambres. Conclusiones: La estructura y desarrollo de las anteras sigue los patrones conocidos de las angiospermas. La microsporogénesis simultánea y el depósito centrípeto de la esporodermis se han descrito previamente para Malvaceae.

Abstract Introduction: Studies on microsporogenesis, micromorphology and structure of pollen grains in Malvaceae are scarce. Objectives: To describe the process of microsporogenesis and micromorphological aspects of pollen grains in A. rosea. Methods: Androphores were processed according to standard protocols for sectioning in paraffin. The obtained sections were stained with Safranin-Alcian blue, Aniline blue was used for immature and unfixed anthers and for resin sections of the androphores, Toluidine blue. Ultrathin sections were observed with transmission electron microscopy. For observation with scanning electron microscopy the material was fixed and dehydrated in 2.2 dimethoxypropane, dried to a critical point and coated with gold. Results: Anthers differentiate from a cell mass at the distal ends of the stamen filaments. The wall of the mature anther presents an outer layer of epidermal cells and an inner layer, the endothecium. Microspore mother cells divide by mitosis and then undergo meiosis to form tetrads. The tapetum is initially cellular and forms a single layer of cells and then loses cellular integrity by invading the microsporangium locule, forming a periplasmodia, by the time the pollen grains are released it degenerated. During sporodermis formation, exine is first deposited and then intine. Pollen grains are pantoporate, apolar, with radial symmetry, spheroidal, with spines, bacula, granules and microgranules. Tectum is perforated with foveolae arranged homogeneously over the whole surface and pollenkit is present. Exine is broad and consists of a thick 3.5 to 4 µm endexine and a thin ektexine (0.6-0.7 µm). The ultrastructure shows columellae forming the infratectum. Capitate glandular unicellular nectariferous trichomes covers the whole surface of the stamen filaments. Conclusions: The structure and development of the anthers follows the known patterns for angiosperms. Simultaneous microsporogenesis and centripetal deposit of the sporodermis have been previously described for Malvaceae.

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Geographic parthenogenesis, range expansion of apomictic plants after climate changes, has been described for Northern Hemisphere gametophytic apomicts. But similar trends have been observed for sporophytic apomicts of Cerrado, the savannas in Brazil. Eriotheca pubescens is a common Cerrado tree, an agamic complex of either hexaploid/polyembryonic apomicts or tetraploid/monoembryonic sexual individuals. Some populations have been described as a new species, Eriotheca estevesiae, all included in the Eriotheca Stellate Trichome Species Complex (ESTSC). Since breeding systems and ploidy are clearly associated with polyembryony and stomatal size, we used these ancillary features to map the reproductive and ploidy level traits of E. pubescens and E. estevesiae. Leaves and seeds were collected from individuals of 19 populations. Seeds were evaluated for the presence of polyembryony and leaves for stomatal measurements. Eight populations were monoembryonic while another eight were polyembryonic and for other three, the embryonic pattern was not readily verified. E. pubescens polyembryonic and hexaploid populations formed a homogeneous group, but monoembryonic plants were more variable. E. estevesiae populations were monoembryonic with smaller stomata. In contrast, some E. pubescens monoembryonic populations further south presented larger stomata. Despite these outliers, possibly mixed populations, stomatal size and embryonic pattern differed from northern to southern populations. Embryonic pattern and stomatal size indicated that northernmost populations of Eriotheca STSC (E. estevesiae) are diploid and sexual. Southernmost populations, mostly polyembryonic and with large stomata, are hexaploid and apomictic. This is in agreement with geographic parthenogenesis and range expansion of apomictic lineages to southern habitats available after the last glacial maximum.

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The first report of Mansonia dyari on Saint Croix, United States Virgin Islands (USVI), is confirmed. Adult and larval specimens were collected in 2018 and 2019 through adult surveillance and larval collections. Specimens were identified by microscopic methods, and a representative specimen was confirmed by DNA sequencing (mitochondrial cytochrome c oxidase subunit I). Morphological features are reviewed and compared with Mansonia flaveola, a species previously reported in the USVI. Notes are provided on the locations, collection methods, and mosquito associates found with Ma. dyari in the USVI.

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Cement industries located nearby limestone outcrops in Brazil have contributed to the coating of cement dust over native plant species. However, little is known about the extent of the response of tropical woody plants to such environmental pollutant particularly during the first stages of plant development and establishment. This work focused on the investigation of possible alterations in leaf structural and ultrastructural traits of 5-month-old Guazuma ulmifolia Lam. (Malvaceae), 6-month-old Myracrodruon urundeuva Allemão (Anacardiaceae), and 9-month-old Trichilia hirta L. (Meliaceae) challenged superficially with cement dust during new leaf development. Leaf surface of plants, the soil or both (leaf plus soil), were treated (or not) for 60 days, under controlled conditions, with cement dust at 2.5 or 5.0 mg cm(-2). After exposure, no significant structural changes were observed in plant leaves. Also, no plant death was recorded by the end of the experiment. There was also some evidence of localized leaf necrosis in G. ulmifolia and T. hirta, leaf curling in M. urundeuva and T. hirta, and bulges formation on epidermal surface of T. hirta, after cement dust contact with plant shoots. All species studied exhibited stomata obliteration while T. hirta, in particular, presented early leaf abscission, changes in cellular relief, and organization and content of midrib cells. No significant ultrastructural alterations were detected under the experimental conditions studied. Indeed, mesophyll cells presented plastids with intact membrane systems. The high plant survival rates, together with mild morphoanatomic traits alterations in leaves, indicate that G. ulmifolia is more resistant to cement dust pollutant, followed by M. urundeuva and T. hirta. Thus, the three plant species are promising for being used to revegetate areas impacted by cement industries activities.

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(Heliocarpus popayanensis Kunth (Malvaceae) tolera a hipoxia do substrato?) Aespécie Heliocarpus popayanensis é muito utilizada em recomposição florística de áreasdegradadas, cujo solo pode apresentar hipoxia. Considerando esses aspectos, este trabalhovisou avaliar resposta desta espécie ao alagamento. Indivíduos com 70 dias foramsubmetidos a substrato drenado(D) e alagado (A) por 30 e 60 dias e a alagado, 30 dias, e adrenado mais 30 dias (A/D). Foram determinados os comprimentos da raiz principal e docaule, a área foliar e o número de folhas, a biomassa e a taxa de crescimento relativo (TCR)de raízes, caules e folhas e o conteúdo nutricional das folhas. Até 60 dias de alagamentohouve redução percentual média na biomassa (38%), na TCR (77%) e área foliar (24%),além de redução no diâmetro do caule e da raiz (70%) e na lignificação de célulasfloemáticas. Nenhuma alteração anatômica ocorreu nas folhas, mas houve redução naconcentração dos nutrientes N, P, K, Fe, Cu e B. Portanto, em condições experimentais,Heliocarpus popayanensis sobrevive a períodos de alagamento, provavelmente pelas alteraçõesmorfoanatômicas. A raridade desta espécie em área alagável deve estar relacionada comoutras etapas do ciclo de vida, como germinação das sementes ou estabelecimento deplântulas e juvenis em competição com outras espécies.

The species Heliocarpus popayanensis is used on floristic recomposition of degradedareas, wich’s soil might present hypoxy. Considering these aspects, this studies evaluatesthis species answers to flooding. Young plants were submitted to drained and floodedsubstract for 30 and 60 days, then flooded for 30 days and then drained for more 30 days.Main root and stem length, area and number of leaves, biomass and relative growth rate ofroots, stems and leaves and the nutritional content of leaves were determined. Until 60 daysof flooding there was a percentual reduction in biomass (38%), in RGR (77%) and in thearea of leaves, including reduction in root and stem’s diameter (70%), and in thelignification of floematic cells. There was no anatomic alteration in leaves, but there wasreduction of nutrients concentration (N, P, K, Fe, Cu, B). Therefore, young plants of thespecies Heliocarpus popayanensis survive to the flooding period considered above, probablydue to anatomical and morphologic alterations. The rarity of this species in flooded area isprobably related to other stages of the life cycle, such as seeds germination or competitionwith other species in the environment.

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(Heliocarpus popayanensis Kunth (Malvaceae) tolera a hipoxia do substrato?) Aespécie Heliocarpus popayanensis é muito utilizada em recomposição florística de áreasdegradadas, cujo solo pode apresentar hipoxia. Considerando esses aspectos, este trabalhovisou avaliar resposta desta espécie ao alagamento. Indivíduos com 70 dias foramsubmetidos a substrato drenado(D) e alagado (A) por 30 e 60 dias e a alagado, 30 dias, e adrenado mais 30 dias (A/D). Foram determinados os comprimentos da raiz principal e docaule, a área foliar e o número de folhas, a biomassa e a taxa de crescimento relativo (TCR)de raízes, caules e folhas e o conteúdo nutricional das folhas. Até 60 dias de alagamentohouve redução percentual média na biomassa (38%), na TCR (77%) e área foliar (24%),além de redução no diâmetro do caule e da raiz (70%) e na lignificação de célulasfloemáticas. Nenhuma alteração anatômica ocorreu nas folhas, mas houve redução naconcentração dos nutrientes N, P, K, Fe, Cu e B. Portanto, em condições experimentais,Heliocarpus popayanensis sobrevive a períodos de alagamento, provavelmente pelas alteraçõesmorfoanatômicas. A raridade desta espécie em área alagável deve estar relacionada comoutras etapas do ciclo de vida, como germinação das sementes ou estabelecimento deplântulas e juvenis em competição com outras espécies.(AU)

The species Heliocarpus popayanensis is used on floristic recomposition of degradedareas, wichs soil might present hypoxy. Considering these aspects, this studies evaluatesthis species answers to flooding. Young plants were submitted to drained and floodedsubstract for 30 and 60 days, then flooded for 30 days and then drained for more 30 days.Main root and stem length, area and number of leaves, biomass and relative growth rate ofroots, stems and leaves and the nutritional content of leaves were determined. Until 60 daysof flooding there was a percentual reduction in biomass (38%), in RGR (77%) and in thearea of leaves, including reduction in root and stems diameter (70%), and in thelignification of floematic cells. There was no anatomic alteration in leaves, but there wasreduction of nutrients concentration (N, P, K, Fe, Cu, B). Therefore, young plants of thespecies Heliocarpus popayanensis survive to the flooding period considered above, probablydue to anatomical and morphologic alterations. The rarity of this species in flooded area isprobably related to other stages of the life cycle, such as seeds germination or competitionwith other species in the environment.(AU)

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Helicteres guazumifolia Kunth and Helicteres baruensis Jacq. (Sterculiaceae) are two sympatric species of shrubs common along the North Western tropical dry forest of Costa Rica. i recorded their nectar production within a 24 hour cycle. i also describe the morphology of extrafloral nectaries with scanning electron microscopy. in H. guazumifolia secretion was restricted to the first day of flower life span, shortly after anthesis (0600 hr - 1800 hr). Flowers secreted on average 15.63 ±8.45 µl (N=409). Nectar is composed of three main sugars: sucrose, fructose and glucose (mainly sucrose). A total of 17 free amino acids were identified: mainly proline, arginine, threonine and tyrosine, with a concentration above 70 Ng/µl. values were different for H. baruensis. Nectar secretion was confined to the second day after anthesis, starting at 1600 hr and ending at 0600 hr the following day. Flowers secreted on average 77.03 ±64.99 µl (N=163) of nectar. Nectar is also composed of three main sugars; however, it showed a tendency to be hexose-rich, having more fructose and glucose than sucrose. There were also 17 free amino acids, mainly proline, alanine, tyrosine, arginine and threonine. Patterns of nectar production are different between the two species for timing, and for amount and composition of nectar secretion. Rev. Biol. Trop. 57 (Suppl. 1): 161-177. Epub 2009 November 30.

Helicteres guazumifolia Kunth y Helicteres baruensis Jacq. (Sterculiaceae) son dos especies simpátricas de arbustos comunes en el bosque tropical seco de la zona noroeste de Costa Rica. Registré los patrones de producción de néctar de las dos especies según la hora del día o de la noche cuando hubo secreción de néctar. En H. guazumifolia se limitó al primer día del período de vida floral, desde el inicio de la antesis a las 0600 hr hasta las 1800 hr. Las flores secretaron en promedio 15.63 ±8.45 µl (N=409) de néctar. El néctar está compuesto por tres azúcares principales: sacarosa, fructuosa y glucosa, y es rico en sacarosa. Se identificó un total de 17 aminoácidos diferentes en el néctar floral. Prolina, arginina, treonina y tirosina fueron los aminoácidos más abundantes con una concentración mayor a 70 Ng/µl. En contraste, las flores de su pariente H. baruensis, secretaron néctar en el segundo día de vida de la flor, después de la antesis; se inició a las 1600 hr y cesó a las 0600 hr del día siguiente. Las flores secretaron en promedio 77.03 ±64.99 µl (N=163) de néctar. El néctar también está compuesto por tres azúcares principales; no obstante, tiende a ser rico en hexosas, con más fructuosa y glucosa que sacarosa. También contiene 17 aminoácidos libres, siendo los más concentrados prolina, alanina, tirosina, arginina y treonina. Se observan claramente patrones diferentes de producción de néctar entre las dos especies según la hora, la cantidad y la composición del néctar. También describí la morfología de los nectarios florales usando fotomicrografías tomadas con microscopio electrónico.

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BACKGROUND AND AIMS: Although orbicular functions are still a matter of debate, they are considered by most authors to be exclusively formed by a secretory tapetum. However, the presence of orbicules on a peritapetal membrane associated with a plasmodial tapetum has been described for Abutilon pictum (Malvaceae) in a previous study. Thus, studies on other species of Malvaceae are necessary to corroborate the presence of such bodies in other members of the family. Pollen and microsporangium development of Modiolastrum malvifolium has been studied in this work. METHODS: Anthers at different stages of development were processed for transmission electron microscopy and light microscopy. Membranes and pollen walls resistant to acetolysis were isolated from whole anthers. KEY RESULTS: Microspore tetrads have a tetrahedral arrangement. Pollen grains are shed at the bicellular stage. The tapetum is invasive, non-syncytial and a peritapetal membrane with orbicules is formed. CONCLUSIONS: This is the first report of the presence of orbicules on a peritapetal membrane in a species with a tapetum of an invasive, non-syncytial type. Taking into consideration all the information on the subject, it can be concluded that the presence of orbicules is not a stable criterion to differentiate between a secretory or plasmodial, or intermediate invasive, non-syncytial tapetum.

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Wood and bark anatomy and histochemistry of Acacia bilimekii Humb. & Bonpl., Acacia cochliacantha Mcbride., Conzatia multiflora (Rob) Stand. and Guazuma ulmifolia Lam.are described from stem samples collected in a tropical dry forest (Morelos,Mexico). Enzyme activities were tested in tangential, radial and transverse cuts of fresh material. Histochemistry and stem anatomy were studied on similar cuts previously softened in a solution of water-glicerol-PEG. Our results show that the anatomical patterns of bark and wood, as well as the histochemical patterns and specific gravity, are influenced by water accessibility and climate; these patterns could guarantee mechanical and anti-infection strategies to support extreme conditions. Enzyme cytochemistry reveals biochemical activities probably related to lipid utilization routes for the lignification processes and for synthesis of extractives; these results suggest that the formation and maturation of woody tissue is very active at the beginning of the rainy season. These species are widely used by the local population. Traditional uses include firewood, dead and live fences, fodder, construction, supporting stakes, handcrafts, farming tools, extraction of tanning products, and medicine. There is no relationship between use and abundance. Alternative uses are proposed according to a density index

Se estudió la anatomía e histoquímica del tallo secundario de Acacia bilimekii, Acacia cochliacantha, Conzatia multiflora y Guazuma ulmifolia. Las muestras de tallo se colectaron en una selva baja caducifolia del estado de Morelos, México. La actividad enzimática se estudió en cortes frescos de caras tangenciales, radiales y transversales. La anatomía e histoquímica se hizo en cortes similares de muestras previamente ablandadas con una mezcla de agua-glicerol-PEG. Los resultados muestran que el patrón anatómico de la corteza y madera, así como las características histoquímicas no enzimáticas están relacionados con el acceso al agua y el clima; estos patrones garantizan que las estrategias mecánicas de resistencia al deterioro les permitan sobrevivir a condiciones extremas. Los resultados de la histoquímica y la citoquímica enzimática sugieren que la lignificación y la síntesis de extractivos a partir de los lípidos de reserva se encuentra activa desde el principio de la estación de lluvias. Se sugieren usos potenciales para las especies estudiads de acuerdo con las densidades relativas

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Wood and bark anatomy and histochemistry of Acacia bilimekii Humb. & Bonpl., Acacia cochliacantha Mcbride, Conzatia nultiflora (Rob) Stand. and Guazuma ulmifolia Lam. are described from stem samples collected in a tropical dry forest (Morelos, Mexico). Enzyme activities were tested in tangential, radial and transverse cuts of fresh material. Histochemistry and stem anatomy were studied on similar cuts previously softened in a solution of water-glicerol-PEG. Our results show that the anatomical patterns of bark and wood, as well as the histochemical patterns and specific gravity, are influenced by water accessibility and climate; these patterns could guarantee mechanical and anti-infection strategies to support extreme conditions. Enzyme cytochemistry reveals biochemical activities probably related to lipid utilization routes for the lignification processes and for synthesis of extractives; these results suggest that the formation and maturation of woody tissue is very active at the beginning of the rainy season. These species are widely used by the local population. Traditional uses include firewood, dead and live fences, fodder, construction, supporting stakes, handcrafts, farming tools, extraction of tanning products, and medicine. There is no relationship between use and abundance. Alternative uses are proposed according to a density index.

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