Comparative cypsela morphology in Campuloclinium DC. and contributions to Eupatorieae tribe (Asteraceae) systematics.

Cypselae anatomical studies have helped to understand the evolution and classification of some groups within Asteraceae. In Eupatorieae, there are many uncertainties about the Campuloclinium circumscription. There are currently two classifications for the genus, and still no consensus for their delimitation. Since structural studies have contributed to the delimitation of groups in Asteraceae, we studied the cypselae of Campuloclinium, searching how the pericarpial taxonomic features could enlighten the genus classification. We studied the fruits of eleven species of this genus through morphological and anatomical observation. Our results showed relevant features to the classification of Campuloclinium and its closely related groups. The stipitate cypsela together with other diagnostic characters are relevant to delimitation of this genus within of Eupatorieae. The trichomes present in cypselae have taxonomic proved to be a possible diagnostic character for the genus, and the six-celled trichomes are essential to distinguish C. campuloclinioides and C. hirsutum. The combination of phylogenetic and structural studies may lead to future research on the delimitation of Campuloclinium and its clades and understand how the stipitate cypselae and the phytomelanin layer evolve in Eupatorieae.

A new report of phytomelanin in cypselae of Vernonieae: the case of the type species of Lychnophora Mart.

Phytomelanin is a mechanically hard, blackish, and inert substance rarely found in plants. In Asteraceae, this substance was historically associated with the Heliantheae alliance, but recent studies have observed it in unrelated groups as Heterocoma and Wunderlichia. During a taxonomic investigation, we found phytomelanin in cypselae of Lychnophora salicifolia an unusual feature in Vernonieae previously found only in Heterocoma. Furthermore, phytomelanin fills the intercellular spaces of the sclerenchymatic outer mesocarp in L. salicifolia. Our results doubt the (syn)apomorphy status in Heterocoma, suggest the phytomelanin may have not the same evolutionary significance in Lychnophorinae as in other tribes and proposes new perspectives for evolutionary studies in Asteraceae.

Roles of mucilage in Emilia fosbergii, a myxocarpic Asteraceae: Efficient seed imbibition and diaspore adhesion.

PREMISE OF THE STUDY: Several angiosperm families have myxodiaspory, such as the Asteraceae in which cypselae are frequently wind-dispersed. The roles of mucilage in cypselae remain misunderstood, and the route of water uptake from substrate to embryo remains unknown. In this work, we analyze the fruits of Emilia fosbergii aiming to clarify how the water is absorbed and how the structure of the pericarp can be related to the processes of diaspore adhesion and seed imbibition. METHODS: The anatomy and ultrastructure of the cypselae of Emilia fosbergii were analyzed with histochemical tests and light, scanning and transmission electron microscopy. We assessed the roles of mucilage in seed imbibition using apoplasmic tracing with Lucifer yellow and epifluorescence microscopy and in adhesion with a sand assay. KEY RESULTS: We describe structural and ultrastructural aspects of the exocarpic cells, especially the mucilaginous twin hairs. Lucifer yellow was absorbed only by the twin hairs, the cells where water primarily enters the seed during seed imbibition. In the sand assay, the mucilage was adhesive. CONCLUSIONS: The twin hairs on the surface of the cypselae can play a dual role in the establishment of new plants of this species. First, these trichomes constitute the main passage for water intake, which is essential for seed imbibition and germination, and after imbibition, they release mucilage that can adhere the diaspore. Therefore, the presence of myxocarpy in Asteraceae could be important in anemochoric species to avoid secondary dispersal.

The role of fibres and the hypodermis in Compositae melanin secretion.

Melanins are dark, insoluble pigments that are resistant to concentrated acids and bleaching by oxidising agents. Phytomelanin (or phytomelan) is present in the seed coat of some Asparagales and in the fruits of some Compositae. In Compositae fruits, melanin is deposited in the schizogenous spaces between the hypodermis and underlying fibrous layer. Phytomelanin in Compositae is poorly understood, and there are only speculations regarding the cells that produce the pigment and the cellular processes involved in the secretion and polymerisation of phytomelanin. This report describes the cellular processes involved in the secretion of phytomelanin in the pericarp of Praxelis diffusa, a species with a structure typical of the family. The ovaries and fruits at different stages were fixed and processed according to the standard methods of studies of light microscopy and transmission electron microscopy. Hypodermal cells have abundant rough endoplasmic reticulum and mitochondria, and the nuclei have chromatin that is less dense than other cells. These characteristics are typical of cells that synthesise protein/amino acids and suggest no carbohydrate secretion. The fibres, however, have a dense cytoplasm rich in the Golgi bodies that are associated with vesicles and smooth endoplasmic reticulum, common characteristics of carbohydrate secretory cells. Our results indicate that the hypodermal cells are not responsible for the secretion of phytomelanin, as previously described in the literature; in contrast, this function is assigned to the adjacent fibres, which have an organisation typical of cells that secrete carbohydrates.

Structure and ontogeny of the pericarp of six Eupatorieae (Asteraceae) with ecological and taxonomic considerations.

The ontogeny of cypselae and their accessory parts were examined using light and scanning electron microscopy for the species Campuloclinium macrocephalum, Chromolaena stachyophylla, Mikania micrantha, Praxelis pauciflora, Symphyopappus reticulatus, and Vittetia orbiculata, some of these being segregated from the genus Eupatorium. A layer of phytomelanin observed in the fruit appears to be secreted by the outer mesocarp into the schizogenous spaces between the outer and inner mesocarp; its thickness was observed to vary among the different species examined. The bristles of the pappus are vascularized, except in M micrantha, and have cells that are superficially projected and arranged acropetally; in S. reticulatus some of the projections are retrorse and a fracture line on the floral disk that is only seen in this species may indicate a double dispersal process. Numerous differences observed among the cypselae examined here reinforce earlier segregations of the genus Eupatorium sensu lato.

Structure and ontogeny of the pericarp of six Eupatorieae (Asteraceae) with ecological and taxonomic considerations

The ontogeny of cypselae and their accessory parts were examined using light and scanning electron microscopy for the species Campuloclinium macrocephalum, Chromolaena stachyophylla, Mikania micrantha, Praxelis pauciflora, Symphyopappus reticulatus, and Vittetia orbiculata, some of these being segregated from the genus Eupatorium. A layer of phytomelanin observed in the fruit appears to be secreted by the outer mesocarp into the schizogenous spaces between the outer and inner mesocarp; its thickness was observed to vary among the different species examined. The bristles of the pappus are vascularized, except in M micrantha, and have cells that are superficially projected and arranged acropetally; in S. reticulatus some of the projections are retrorse and a fracture line on the floral disk that is only seen in this species may indicate a double dispersal process. Numerous differences observed among the cypselae examined here reinforce earlier segregations of the genus Eupatorium sensu lato.

A ontogênese das cipselas e de suas partes acessórias em Campuloclinium macrocephalum, Chromolaena stachyophylla, Mikania micrantha, Praxelis pauciflora, Symphyopappus reticulatus e Vittetia orbiculata, parte delas segregadas do gênero Eupatorium, foi estudada em microscopia de luz e eletrônica de varredura. A camada de fitomelanina presente no fruto aparentemente é secretada pelo mesocarpo externo e possui espes-sura variavel entre as especies, depositando-se em espaco esquizógeno entre o mesocarpo externo e interno. As cerdas dos pápus são vascularizadas, exceto em . M. micrantha, e possuem células projetadas superficialmente, dispostas acropetamente; em S. reticulatus, algumas projeções são retrorsas e a presença de linha de fratura sob o disco floral, observada apenas nesta espécie, pode indicar processo duplo de dispersão. As numerosas diferencas registradas entre as cipselas estudadas reforcam se-gregações anteriores do gênero Eupatorium sensu lato.

Morfoanatomia e ontogênese dos frutos e sementes de Clusia lanceolata Cambess (Clusiaceae) / Morphology, anatomy and ontogeny of the fruits and seeds of Clusia lanceolata Cambess (Clusiaceae)

Clusia lanceolata Cambess é espécie arbustiva da Mata Atlântica. Caracteriza-se por ser dioica, com flores estaminadas e pistiladas grandes, vistosas, de coloração rosa, apresentando a parte interna vinácea. Foram descritos aspectos morfológicos e estruturais dos frutos e sementes dessa espécie, visando classificar corretamente o seu tipo de fruto e, também, confirmar a origem do apêndice carnoso que envolve as sementes. O material botânico utilizado constou de flores em antese e frutos, em quatro estádios de desenvolvimento, coletados de dois espécimes. Os estudos morfológicos e anatômicos foram realizados segundo técnicas usuais. O fruto é cápsula septífraga, esférica, de coloração verde-avermelhado. O exocarpo é unisseriado; o mesocarpo parenquimático contém numerosos ductos secretores e feixes vasculares, de disposição principalmente longitudinal. O endocarpo é derivado da epiderme interna do ovário e de três a quatro camadas subepidérmicas, cujas células alongam-se tangencialmente e a parede que delimita o lóculo sofre lignificação. A abertura se faz pela sutura carpelar, por meio de uma faixa de células parenquimáticas de tamanho reduzido, que se bifurca em direção aos lóculos no meio dos septos. Os óvulos anátropos bitegumentados, com endotélio e hipóstase, originam sementes também anátropas, exotégmicas e envolvidas por arilo de origem funicular e exostomal. O embrião é hipocotilar.

Clusia lanceolata Cambess. is a shrub species native to the Atlantic Forest. The plant is dioecious, with large, showy, pink staminate and pistillate flowers that are wine-colored internally. The morphological and structural aspects of the fruits and seeds of this species are described here in order to correctly classify the fruit type and to determine the origin of the fleshy appendage that surrounds the seeds. The botanical material utilized here contained flowers in anthesis and fruits in four stages of development, and were collected from two different plants. The morphological and anatomical studies were performed according to traditional techniques. The fruit is a septifrage, spherical capsule with a reddish-green coloration. The exocarp is uniseriate; the parenchymatous mesocarp contains numerous secretory ducts and vascular bundles arranged in predominantly longitudinal positions. The endocarp is derived from the internal epidermis of the ovary and has from three to four subepidermal layers whose component cells are tangentially elongated, and the cell walls lining the locule become lignified. The fruits open by means of the carpelar suture, along a stand of small parenchymous cells that bifurcate in the direction of the locules, in the midst of the septum. The anatropous bi-tegumented ovules, with an endothelium and hypostase, give rise to seeds that are likewise anatropous, exotegmic, and wrapped in an aril that has a funicular and exostomal origin. The embryo is hypocotylar.

Morphology and development of seedlings and saplings of weeds - DOI: 10.4025/actascibiolsci.v29i3.475 / Morfologia de plântulas e estádios juvenis de espécies invasoras - DOI: 10.4025/actascibiolsci.v29i3.475

The morphology of 20 species of weeds that occur in the most common crops in Maringá, Paraná State, Brazil and adjacent regions were described at early developmental stages, in order to identify the species in the field and provide information for taxonomic and ecological works. Sixteen species featured epigeal-foliaceous seedlings. The seedling in Cardiospermum halicacabum is epigeal-fleshy; in Cenchrus echinatus and Digitaria horizontalis it is hypogeal and in Commelina virginica is epigeal-cryptocotyledonar. The differentiation of the first eophyll occurred within ten (Digitaria horizontalis) to 35 days (Bidens pilosa) and the first metaphyll appeared within 22 (Commelina virginica) to 49 days (Acanthospermum australe). The number of eophylls varied from one to four, and the phyllotaxis varied from alternate to opposite.

Plântulas e plantas jovens de vinte espécies de plantas invasoras, que ocorrem nas culturas mais freqüentes de Maringá, Estado do Paraná, Brasil e regiões adjacentes, foram descritas morfologicamente, e contribuem para identificação no campo e fornecem informações para trabalhos taxonômicos e ecológicos. Em 16 espécies, a plântula é epígeo-foliácea. Em Cardiospermum halicacabum, é epígeo-carnosa; em Cenchrus echinatus e Digitaria horizontalis, é hipógea; e, em Commelina virginica, é criptocotiledonar-epígea (tipo Durio). A diferenciação do primeiro eofilo variou de dez (Digitaria horizontalis) a 35 dias (Bidens pilosa) e do primeiro metafilo de 22 (Commelina virginica) a 49 dias (Acanthospermum australe). O número de eofilos formados variou de um a quatro e a filotaxia, de alterna a oposta.