Computer Program for Three-Dimensional Reconstructions and Numerical Analyses of Plant Organs from Serial Sections

Niklas, Karl J.; Boyd, Steven P.

doi:10.2307/2444054

Cited by 11 publications

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“…Sections were stained with phloroglucinol, to identify lignified tissues, and photographed with Kodachrome slide film. The spatial distribution of different tissues was determined visually and quantitative measurements were made of transverse tissue area by digitizing the outlines of tissues into the memory ofan IBM PC-XT computer (see Niklas and Boyd, 1987). Data are presented for the absolute and relative volume fractions of thick walled, lignified tissues (referred to as "support" tissues) and thin walled, nonlignified tissues ("ground" tissues).…”

Section: Methodsmentioning

confidence: 99%

Flexural Stiffness Allometries of Angiosperm and Fern Petioles and Rachises: Evidence for Biomechanical Convergence

Niklas¹

1991

Evolution

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Evidence for convergence in biomechanical and anatomical features of leaves (elastic modulus E, second moment of area I, taper of petioles, the longitudinal distribution of petiolar and laminar weight, and volumes of tissues) is presented based on a survey of 22 species (distributed among dicots, monocots, and ferns). In general, regardless of taxonomic affinity, petioles were found to be mechanically constructed in one of two ways: Type I petioles-as cantilevered, end-loaded beams with relatively uniform flexural stiffness (EI) (simple and palmate leaves); and Type II petioles-as tapered cantilevered beams whose static loadings (biomass) and EI increase basipetally (pinnate leaves). In general, collenchyma and sclerenchyma were found to be peripherally located in transections through Type I and II petioles, respectively. Statistical analyses within each species and among species with either type of petiole indicated that EI ≈ k Lp and EI ≈ k Lp for Type I and II petioles, respectively, where k and k are dimensional constants and Lp is petiolar length. The data are interpreted to indicate that Type I and II petioles mechanically operate to deal with static loadings in two distinct ways, such that Type II petioles function in an analogous manner to branches supporting separate leaves (leaflets). The convergence in mechanical "designs" among taxonomically distinct lineages (angiosperms and ferns) is interpreted as evidence for selection on mechanical attributes of load supporting structures (petioles).

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Section: Methodsmentioning

confidence: 99%

Flexural Stiffness Allometries of Angiosperm and Fern Petioles and Rachises: Evidence for Biomechanical Convergence

Niklas¹

1991

Evolution

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“…The outline of each section and of individual cell lumens were digitized into the memory of an IBM PC-XT, and transverse areas were calculated by SECTION (a software package designed to compute transverse area, perimeter length, and surface area to volume of three-dimensional anatomical structures; see Niklas and Boyd, 1987). Transverse sections were cut through the base, mid-region, and tip of each shoot (N = 66).…”

Section: Methodsmentioning

confidence: 99%

Safety Factors in Vertical Stems: Evidence from Equisetum hyemale

Niklas¹

1989

Evolution

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Predictions from a mechanical model for hollow vertical stems are tested against morphometric and mechanical studies of the vertical stems of Equisetum hyemale. The model predicts 1) that the wall thickness of hollow internodes must be at least 15% of the external radius of shoots, 2) that the elastic modulus of stems is quantitatively related to the ratio of apoplast (cell walls) to symplast (cytoplasm) areas in transverse sections through stems, and that (3) hollow stems are designed to sustain an additional and significant proportion of their own weight. The “safety factors” predicted for a hollow vertical stem are used to examine two adaptationist explanations for hollow stems: 1) “economy in design,” which argues that natural selection will favor a reduction in the metabolic cost in constructing an organ, and 2) “mechanical design,” which argues that stems are designed to maximize their mechanical stability during vertical growth. Evidence from E. hyemale indicates that 1) there is a developmental limit to the maximum allotment of biomass invested in the construction of stems, 2) as stem height increases, morphometric adjustments in internodal wall thickness occur which converge on predicted safety limits, and 3) the elastic modulus of stems changes as a function of the ratio of apoplast to symplast areas seen in transverse sections through shoots. Biomechanical and developmental evidence and the allometry of E. hyemale stems are consistent with the view that stems are designed for safety and are inconsistent with some predictions based on the economy in design.

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A Dynamic Multidisciplinary Approach to Floral Morphology

Rutishauser

1989

Progress in Botany

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Computer Program for Three-Dimensional Reconstructions and Numerical Analyses of Plant Organs from Serial Sections

Cited by 11 publications

References 0 publications

Flexural Stiffness Allometries of Angiosperm and Fern Petioles and Rachises: Evidence for Biomechanical Convergence

Flexural Stiffness Allometries of Angiosperm and Fern Petioles and Rachises: Evidence for Biomechanical Convergence

Safety Factors in Vertical Stems: Evidence from Equisetum hyemale

A Dynamic Multidisciplinary Approach to Floral Morphology

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