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: In recent DNA-based cladograms of dicotyledons, Aextoxicaceae and Berberidopsidaceae form an isolatedCladistics does not use symplesiomorphies, which are numerous between the two families, to group closely-related families at clade tips.
Abstract: In recent DNA-based cladograms of dicotyledons, Aextoxicaceae (one sp., Chile) and Berberidopsidaceae (three spp., Chile and Australia) form an isolated clade, Berberidopsidales, basal to rosids and asterids. Until recently, Aextoxicaceae had been placed in Euphorbiales, Berberidopsidaceae in Violales. Light microscopy and scanning electron microscopy (SEM) studies of wood of the two families show numerous shared primitive features: perforation plates with numerous bars and extensive pit-membrane remnants, lateral wall pitting of vessels scalariform to transitional, tracheids present; long vessel elements and tracheids, low F/V ratio; diffuse axial parenchyma; and Heterogeneous Type I rays. Features reported for the first time include crystals with various degrees of encapsulation in ray cells (Aextoxicon), pit membrane remnants in perforations (Berberidopsis, previously reported in Aextoxicon), and presence of narrow latewood vessels the perforation plates of which can bear pit membranes (Berberidopsis). Probable synapomorphies of the two families include marked difference between multiseriate parts (cells procumbent only) and uniseriate parts (cells square to upright), and presence of dark-staining deposits in axial parenchyma and rays. Cladistics does not use symplesiomorphies, which are numerous between the two families, to group closely-related families at clade tips. Ecological and habital adaptations of woods of the two families are briefly considered.
18 citations
TL;DR: The developmental processes leading to the structure of the secondary tissues in the axis of Halogeton glomeratus are studied and a high degree of evolutionary specialization is shown, based on the criteria of vessel element size, endwall inclination, and pitting.
Abstract: We studied developmental processes leading to the structure of the secondary tissues in the axis of Halogeton glomeratus. Secondary vascular tissue is associated with, or embedded in, conjunctive tissue. The secondary tissues of the stem and root exhibit two distinct structural patterns which are products of successive, extrafascicular, bidirectional cambia of varying circumference. This kind of secondary growth is not homologous with the secondary growth typical of most conifers and woody and herbaceous dicotyledons of temperate regions. The secondary vascular tissues of both stem and root show a high degree of evolutionary specialization, based on the criteria of vessel element size, endwall inclination, and pitting. The stem lacks rays, whereas the root has discernible raylike cell aggregates. Terminology and adaptive significance of the type of secondary growth in the Chenopodiaceae and related families are considered.
18 citations
TL;DR: The genus Heteromorpha is revised, data are analyzed cladistically and the supposed phylogeny is presented in the form of a cladogram.
Abstract: The genus Heteromorpha is revised. Seven species (including seven varieties) are recognized. Eight species from Madagascar are excluded. The name H. stenophylla Welw. ex Schinz is reinstated and H. transvaalensis Schltr. & H. Wolff is considered a variety of it. A new species, H. occidentalis P. J. D. Winter, is described. A narrower view of H. arborescens (Spreng.) Cham. & Schltdl. than that of recent authors is applied; the species is subdivided into five varieties. Two of these, var. frutescens P. J. D. Winter and var. montana P. J. D. Winter are new. The circumscription of H. involucrata Conrath is broadened to accommodate other central African forms of the species; H. stolzii H. Wolff is added to the synonymy. Data are analyzed cladistically and the supposed phylogeny is presented in the form of a cladogram.
18 citations
TL;DR: This is a report of investigations of the petrified woods from the Cypress Hills Formation (Oligocene) of Saskatchewan and it is interesting to note here that except for the Pinaceae none of these families is now a part of the flora of this region.
Abstract: This is a report of investigations of the petrified woods from the Cypress Hills Formation (Oligocene) of Saskatchewan. Families represented are Pinaceae (Pinoxylon hanlinei sp. nov.), Taxodiaceae (Sequoioxylon gypsaceum (Gothan) Greguss), Magnoliaceae (Magnolioxylon michelioides Hofmann), Simaroubaceae (Ailanthoxylon canalosum sp. nov.), Hamamelidaceae (Liquidambaroxylon speciosum Felix), and Juglandaceae (Eucaryoxylon canadensis sp. nov.). It is interesting to note here that except for the Pinaceae none of these families is now a part of the flora of this region. Presently genera of the other families occur in the eastern and southwestern United States, in the southeastern part of Canada (Carya), or in eastern Asia.
18 citations
TL;DR: The genus Raputia, based on R. aromatica from French Guiana, comprises 10 species, which range from Venezuela and French Guiano to Amazonian Colombia, Peru, and Brazil, and three new species are described.
Abstract: Raputia, based onR. aromatica from French Guiana, comprises 10 species, which range from Venezuela and French Guiana to Amazonian Colombia, Peru, and Brazil. The genus can be recognized by the combination of opposite, 1-or 3-foliolate leaves cauline, circinate inflorescences; quincuncial sepals; and white or green, ± fleshy, 2-lipped corollas. Three new species are described:R. brevipedunculata from French Guiana and Amapa, BrazilR. megalantha from Amazonian Peru and adjacent Brazil; andR. simulans from the upper Amazon basin of Brazil, Colombia, and Peru. Three new combinations are made:R. amazonica, R. szczerbanii, and R. hirsuta, and as a result of the latter,Achuaria becomes a synonym ofRaputia. A key to and descriptions and distribution maps of the species are prowided.
18 citations