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: A data matrix of 143 morphological and chemical characters for 142 genera of euasterids according to the APG system was compiled and complemented with rbcL and ndhF sequences for most of the genera and indicates that Adoxaceae are closely related to Dipsacales and hence they should be included in that order.
Abstract: A data matrix of 143 morphological and chemical characters for 142 genera of euasterids according to the APG system was compiled and complemented with rbcL and ndhF sequences for most of the genera. The data were subjected to parsimony analysis and support was assessed by bootstrapping. Strict consensus trees from analyses of morphology alone and morphology + rbcL + ndhF are presented. The morphological data recover several groups supported by molecular data but at the level of orders and above relationships are only superficially in agreement with molecular studies. The analyses provide support for monophyly of Gentianales, Aquifoliales, Apiales, Asterales, and Dipsacales. All data indicate that Adoxaceae are closely related to Dipsacales and hence they should be included in that order. The trees were used to assess some possible morphological synapomorphies for euasterids I and II and for the orders of the APG system. Euasterids I are generally characterised by opposite leaves, entire leaf margins, hypogynous flowers, “early sympetaly” with a ring-shaped corolla primordium, fusion of stamen filaments with the corolla tube, and capsular fruits. Euasterids II often have alternate leaves, serrate-dentate leaf margins, epigynous flowers, “late sympetaly” with distinct petal primordia, free stamen filaments, and indehiscent fruits. It is unclear which of these characters represent synapomorphies and symplesiomorphies for the two groups, respectively, and there are numerous expections to be interpreted as reversals and parallelisms.
73 citations
TL;DR: Scanning electron microscopy has been used to examine the location and form of crystals in the stems of woody perennials and the results are discussed in relation to the effects of physical conditions and 'impurities' upon crystal form.
72 citations
TL;DR: These novel allometries suggest design rules operating at the smallest scales of leaf construction and the possibility of applying these relationships to better characterizing the basis for differences among species in leaf form and functional traits are suggested.
Abstract: UNLABELLED PREMISE OF THE STUDY Allometric relationships among the dimensions of leaf cells, cell walls, and tissues, and whole-leaf thickness and area are likely to have key implications for leaf construction and function, but have remained virtually untested, despite the explosion of interest in allometric analysis of numerous plant properties at larger scales. • METHODS Using leaf transverse cross sections and light microscopy, we measured leaf dimensions, tissue thicknesses, mesophyll and xylem cell sizes, and cell wall thicknesses for 14 diverse angiosperm species of wet and dry habitats and tested hypothesized allometric relationships based on geometric scaling due to development and/or function. • KEY RESULTS We found strong novel allometries relating the dimensions of cells, cell walls, tissues, and gross leaf form. Cell sizes and cell wall thicknesses tended to scale isometrically across mesophyll tissues within the leaf, such that species with large cells or thick cell walls in one tissue had these also in the other tissues; however, leaf vein xylem conduit sizes were independent of those of other cell types. We also found strong geometric scaling of cell wall thicknesses with cell sizes throughout the mesophyll, but not in the leaf vein xylem. Further, leaf thickness scaled with cell sizes, cell wall thicknesses and the thicknesses of component mesophyll tissues, but leaf area was independent of anatomical traits across species. • CONCLUSIONS These novel allometries suggest design rules operating at the smallest scales of leaf construction and the possibility of applying these relationships to better characterizing the basis for differences among species in leaf form and functional traits.
72 citations
TL;DR: It seems probable that the articulated and non-articulated types of Euphorbiaceae are not as divergent as commonly supposed, since both may undergo intrusive growth, although more ontogenetic studies are needed to clarify the relationship between them.
72 citations