Micromorphological features revealing two new species of Portulaca (Portulacaceae) from Brazil, segregated from P. hirsutissima

Santos, Thaíla Vieira Alves dos; Coelho, Alexa Araújo de Oliveira Paes; Dórea, Marcos da Costa; Santos, Francisco de Assis Ribeiro dos; Leite, Kelly Regina Batista; Oliveira, Reyjane Patrícia de

doi:10.11646/phytotaxa.270.2.3

Cited by 9 publications

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“…In core Caryophyllales, waxes on the seed surface are present in Simmondsia (Simmondsiaceae: Gülz and Hangst, 1983 ), some Cactaceae ( Barthlott and Voit, 1979 ), Montiaceae ( Obbens, 2006 ), Caryophyllaceae ( Barthlott, 1981 ; Minuto et al., 2006 ; Romanova and Kravtsova, 2019 ), rarely in Portulaca (Portulacaceae: Danin et al., 2008 ; Santos et al., 2015 ), and in Molluginaceae ( Sukhorukov and Kushunina, 2017 ; Sukhorukov et al., 2018b ). In the species researched to date, waxes are found on seeds in multi-seeded fruits.…”

Section: Discussionmentioning

confidence: 99%

Evolution of seed characters and of dispersal modes in Aizoaceae

Sukhorukov

Nilova²,

Kushunina³

et al. 2023

Front. Plant Sci.

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The family Aizoaceae includes ~1880 species and is one of the more diverse groups within Caryophyllales, particularly in arid areas in the western part of southern Africa. Most species are dwarf succulent-leaf shrubs. In response to the harsh climatic conditions prevalent where they occur, many representatives have evolved special reproductive adaptations. These include hygrochastic capsules (mostly found in Mesembryanthemoideae and Ruschioideae), burr-like indehiscent and one-seeded, winged diaspores, and fast germination of seeds after rain. We focused on anatomical features, evolutionary trends, and the ecological significance of various morpho-anatomical structures found in the seeds. The seeds of 132 species from 61 genera were studied, and 18 diagnostic characters were discovered. All studied characters were compared with those of other families from core Caryophyllales. The seed notch and embryo shape were added to the list of characteristics distinguishing major clades within the family. In addition, the presence of longitudinal ridges and a keel on the seed are additional characters of Aizooideae and combined Ruschioideae-Apatesieae, respectively. Puzzle-like borders of testa cells are a common trait in Ruschioideae and Mesembryanthemoideae. Most taxa in Aizoaceae have a thin seed coat, which is the ancestral state within the family. This may facilitate fast germination. We observed several shifts to a medium-thick or thick seed coat in members of Ruschioideae and Acrosanthoideae. These inhabit fire-prone environments (in vegetation types known as fynbos and renosterveld), where the thickened seed coat may protect against damage by fire. Multi-seeded fruits are the ancestral state within Aizoaceae, with several shifts to one-(two-)seeded xerochastic fruits. The latter are dispersed via autochory, zoochory, or anemochory. This trait has evolved mainly in less succulent subfamilies Acrosanthoideae, Aizooideae, and Sesuvioideae. In highly succulent subfamilies Ruschioideae and Mesembryanthemoideae, fruits are almost exclusively multi-seeded and hygrochastic with ombrohydrochoric dispersal. A reduction in the number of seeds within a dispersal unit is rare. Within Apatesieae and Ruschieae, there are also a few unusual genera whose fruits fall apart into one- to two-seeded mericarps (that are mainly dispersed by wind).

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Section: Discussionmentioning

confidence: 99%

Evolution of seed characters and of dispersal modes in Aizoaceae

Sukhorukov

Nilova²,

Kushunina³

et al. 2023

Front. Plant Sci.

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“…Portulacaceae Juss. Portulaca L. Figura 24 c-d Morfologia polínica: mônade, apolar, esferoidal, tamanho médio, pantocolpado, equinado (Kim 2013, Santos et al 2016.…”

Section: Phyllanthus L Figura 23 G-hunclassified

Catálogo polínico de um testemunho pleistocênico da turfeira Sempre-Vivas inserida no Bioma Savana Tropical, Brasil

Fonseca

Horák‐Terra

Silva

et al. 2021

Hoehnea

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RESUMO Este estudo apresenta a análise polínica de uma turfeira localizada no Parque Nacional das Sempre-Vivas (PNSV), na Serra do Espinhaço Meridional, município de Diamantina, Estado de Minas Gerais, Brasil, para fornecer material de referência para a identificação de grãos de pólen preservados em solo de Cerrado durante o Pleistoceno e Holoceno. A análise abrangeu 16 níveis estratigráficos de um testemunho de sondagem de 162 cm de comprimento, correspondentes aos últimos 32.800 anos cal AP. A preparação química consistiu de lavagem ácida com HCl, HF, acetólise e tamisação por banho de ultrassom, com montagem do resíduo polínico em lâminas de microscopia com gelatina glicerinada. A análise foi realizada com base em observações morfológicas sob microscopia óptica e ilustrações dos grãos de pólen com base em literatura especializada. Foram identificados 116 tipos polínicos relacionados às fitofisionomias florestais ocorrentes no PNSV representadas pelas florestas semidecídua e montana, e pelas fitofisionomias do Cerrado (latu senso), áreas florestadas e formações campestres. As características morfológicas dos grãos de pólen foram bastante variáveis e podem ser utilizadas como indicadores nas reconstruções paleoambientais da sucessão da vegetação e condições paleoclimáticas do bioma Savana Tropical (Cerrado).

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