Anatomy of the Dicotyledons.
About: This article is published in American Midland Naturalist.The article was published on 1950-11-01. It has received 2511 citations till now.
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TL;DR: The anatomy and morphology of vegetative and reproductive structures of the monotypic, dicotyledonous genus Oncotheca were studied and support is given to the elevation of the genus to familial status and its placement near the Theaceae.
Abstract: The anatomy and morphology of vegetative and reproductive structures of the monotypic, dicotyledonous genus Oncotheca were studied to evaluate the svstematic relationships of this New Caledonian endemic. Wood has remained at a low level of advancement, as evidenced by the solitary, angular pores and exclusively scalariform perforation plates. Imperforate tracheary elements are fiber tracheids, and asial parenchyma is diffuse to diffuse in aggregates in distribution. Sieve tube elements possess oblique to very oblique, compound sieve plates. Nodal anatomy is pentalacunar, and petioles contain a single, undissec.ted arc of vascular tissue. A number of apparently xeromorphic leaf features, including general foliar coriaceousness, may result from the poor availability of soil minerals. Leaves are characterized by a thick cuticle, uniseriate epidermis with nearly anomocytic stomata having paracytic or tetracytic tendencies and a bifacial mesophyll with two or three hypodermal layers. Foliar venation is brochidodromous. Highorder venation is characterized by freely ending branched veinlets and imperfect areolation. Flowers are relatively advanced, as evidenced by extensive fusion of parts and the tlnion of major floral bundles such as the ventral carpellary traces. A c]ose relationship between Oncotheca and the Aquifoliaceae and Ebenaceae is refuted. Support is given to the elevation of the genus to familial status and its placement near the Theaceae.
21 citations
TL;DR: In this paper, the authors present an analysis of the stratigraphic sequence of Montou (Eastern Pyrenees, France) covering a period from the middle Neolithic to the late Bronze Age.
Abstract: The stratigraphic sequence of Montou (Eastern Pyrenees, France) covers a period from the middle Neolithic to the late Bronze Age. Environmental changes are noticed since the middle Neolithic, when the decline of the deciduous oak favours, in the long term, the evergreen oaks. The Chalcolithic period witnesses the arrival and spread of mesomediterranean and thermomediterranean plant formations. This evolution may result from increasing anthropogenic pressure as shown by the maintenance of a garrigue vegetation during the Bronze Age. The association charcoal analysis/quantitative anatomy offers new perspectives concerning vegetation changes. Both approaches record the existence of mesomediterranean bioclimatic conditions during the middle Neolithic; thermomediterranean affinities are recorded first, by charcoal analysis, during the early Bronze Age, and by eco-anatomy during the transition from the middle to the late Bronze Age. Quantitative anatomy also pinpoints (1) the existence of two humid phases, (2) an increase in mean annual temperature, and (3) the exploitation and management of the olive tree since the early Bronze Age.
21 citations
TL;DR: In this article, the chemical composition of the essential oil from root and rhizome, obtained by hydrodistillation, was analyzed by gas chromatography-flame ionization detection and GC-mass spectrometry.
21 citations
TL;DR: Dentre as caracteristicas anatomicas importantes para a sua identificacao destacam-se parenquima cortical radical com esclereides; cortex caulinar com faixas descontinuas de colenquima e tecido vascular organizado em dois circulos descont inuos de feixes colaterais.
Abstract: Objetivando auxiliar trabalhos taxonomicos e farmacobotânicos, foram realizados estudos morfoanatomicos dos orgaos vegetativos de Piper crassinervium H.B. & K. (jaborandi). O material foi analisado seguindo-se tecnicas usuais de corte e coloracao. P. crassinervium e um arbusto de caule ereto, de folhas estipuladas e alternas. Dentre as caracteristicas anatomicas importantes para a sua identificacao destacam-se: parenquima cortical radical com esclereides; cortex caulinar com faixas descontinuas de colenquima e tecido vascular organizado em dois circulos descontinuos de feixes colaterais, delimitados por endoderme com estrias de Caspary; folha dorsiventral, hipoestomatica, com estomatos ciclociticos e tetraciticos e hipoderme unisseriada, porem, com 1-3 camadas de celulas na regiao da nervura principal; parenquima clorofiliano com idioblastos oleiferos; tricomas glandulares na epiderme unisseriada e idioblastos com pequenos cristais aciculares no parenquima em todos os orgaos.
21 citations
TL;DR: The results show that the presence of raphides mixed with pollen seems to be a widespread phenomenon in the aroid family.
21 citations