1997 Cover Stories

On this page we are pleased to provide you with explanations for the beautiful pictures that make up the covers for the American Journal of Botany, Volume 84 (1997). At present we are displaying only the last for covers for the 1997 year as these are the first issues covers that appear on the internet. We hope you enjoy the stories they tell and open up your possibilities for asking new questions! For members, the links created by the pictures take you back to the specific issue of the AJB.

abot841 Cover Illustration V84.1: The growth of a bean (Phaseolus vulgaris L.) root system for 10 d, as simulated by SimRoot, a dynamic simulation model of botanical root systems based on empirical growth parameters. The three-dimensional fractal dimension of the root system was estimated by superimposing three-dimensional grids of varying size on the simulated root system in order to estimate the number of boxes in the three dimensional grid that was intercepted by the simulated root system. Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see KL Nielsen, JP Lynch and HN Weiss: Fractal geometry of bean root systems: correlations between spatial and fractal dimension

abot842 Cover Illustration V84.2: Pyllocladus glaucus Carr. (Phyllocladaceaes), Toatoa or Blue Celery Pine, endemic to New Zealand, showing part of a pseudowhorl of fertile phylloclades. Cones are borne marginally towards the base of these modified branch complexes. The individual ovules with pollination drops are at the stage of pollen receptivity. Magnification x5, from a color transparency by J. E. Braggins. Image credit, J. E. Braggins Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see PB Tomlinson, JE Braggins and JA Rattenbury: Contrasted pollen capture mechanisms in Phyllocladaceae and certain Podocarpaceae (Coniferales)

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Cover Illustration V84.3: Alpha carbon backbone of the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase, color coded to show residues conserved throughout the 300 million years of evolution of the seed plants. Absolutely conserved residues in red, residues with one substitution in green, and variable sites in blue. Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see EA Kellogg and ND Juliano: The structure and function of RuBisCO and their implications for systematic studies

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Cover Illustration V84.4: A capitulum of the South African "beetle daisy" (Gorteria diffusa: Asteraceae). The dark raised spots on the ray florets are strikingly similar to the bee-fly (Megapalpus nitidus: Bombyliidae) that pollinates this plant. Experiments show that bee-flies are more strongly attracted to capitula with spots than capitula in which spots have been removed. Image credit, Steve Johnson Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see SD Johnson and JJ Midgley: Fly pollination of Gorteria diffusa (Asteraceae), and a possible mimetic function for dark spots on the capitulum

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Cover Illustration V84.5: A compound leaf and scattered wing nuts of Polyptera manningii Manchester et Dilcher (extinct Juglandaceae) in siltstone from the paleocene of southwestern Wyoming. Width of the specimen is 15 cm. Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see SR Manchester and DL Dilcher: Reproductive and vegetative morphology of Polyptera (Juglandaceae) from the Paleocene of Wyoming and Montana

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Cover Illustration V84.6: Plants of Oreocereus celsianus growing in the altiplano of northern Argentina at an altitude of 4000 m. These cacti have dimorphic wood. While young and small they produce a soft spongy wood and the body is supported by turgor. When older, taller, and heavier they produce a fibrous wood strong wnough to support the body. Image credit, James D. Mauseth Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see JD Mauseth and BJ Plemons-Rodriguez: Presence of paratracheal water storage tissue does not alter vessel characters in cactus wood

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Cover Illustration V84.ABSTRACTS: Vaccinium vitis-idaea L. growing on the ultramafic rock of Mt. Albert, Gaspè Peninsula, Quèbec. The alpine Gaspè highlands, with their arctic-alpine flora, and the ultramafic outcrops of Mt. Albert, which harbor both arctic-alpine disjunct and enedemic taxa, contribute significantly to the biodiversity of this area of boreal forest. Image credit, Luc Brouillet Link to larger JPEG of the image

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Cover Illustration V84.7: Protomycena electra Hibbett, Grimaldi, & Donoghue gen. Et sp. Nov. (Fungi Basidiomycota). This mushroom was found in Dominican amber and is ~15-30 million years old. It is remarkable not only for its exquisite preservation, but also for its striking morphological resemblance to extant mushrooms in Mycena and other Tricholomataceae. Protomycena is one of only three known fossil mushrooms. Image credit, David Grimaldi Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see DS Hibbett, D Grimaldi and MJ Donoghue: Fossil mushrooms from Miocene and Cretaceous ambers and the evolution of Homobasidiomycetes

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Cover Illustration V84.8: Flow visualizations (rose bengal dye in top view; milk in bottom view) around three carpellate flowers of Zostera marina in a flow chamber at an ambient velocity of ~2 cm/s. Image credit, Josef Daniel Ackerman Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see JD Ackerman: Submarine pollination in the marine angiosperm Zostera marina (Zosteraceae). I. The influence of floral morphology on fluid flow and Submarine pollination in the marine angiosperm Zostera marina (Zosteraceae). II. Pollen transport in flow fields and capture by stigmas

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Cover Illustration V84.9: Vessel contents in the petiole of a transpiring sunflower leaf. Vessels containing water shown in green, gas spaces (embolisms) in red. Some vessels are completely embolized, others contain varying amounts of water as well as gas. The proportion of embolized vessels was followed during a day's transpiration. Petioles were snap-frozen intact on the transpiring plant, and viewed, still frozen, in the cryo-scanning microscope. Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see MJ Canny: Vessel contents of leaves after excision - a test of Scholander's assumption and Vessel contents during transpiration - embolisms and refilling

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Cover Illustration V84.10: Transverse view showing internal structure of a plasmodesma of the charophycean green alga Chara zeylanica. Digital false color computer-enhanced image from a tramission electron micrograph. A central structure appears to be connected to the plasma membrane via spoke-like structures, a feature held in common with plasmodesmata of higher plants. Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see ME Cook et al.: Comparative ultrastructure of plasmodesmata of Chara and selected bryophytes: toward an elucidation of the evolutionary origin of plant plasmodesmata

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Cover Illustration V84.11: Tassel seed mutations in maize. Maize plants bear two different types of inflorescences, the tassel and the ears. The tassel is branched and has made flowers, while the ears are unbranched and have female flowers. This occurs by formation of initially hermaphroditic flowers, followed by the selective abortion of male reproductive organs (stamens) in ear flowers and of female reproductive organs (pistils) in tassel flowers. the tassel seed mutations alter this pattern by allowing pistils to develop in flowers on the tassel seed mutations, such as Ts6 and ts4, also cause extra branches to form in the tassel (Ts6, left) and on the ear (Ts6,right; ts4, center). Image credit, Erin Irish Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see EE Irish: Class II tassel seed mutations provide evidence for multiple types of inflorescence meristems in maize (Poaceae)

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Cover Illustration V84.12: G. Ledyard Stebbins, Jr. Image credit, Dane A. Penland (Smithsonian photograher, 1982) Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see VB Smocovitis: G. Ledyard Stebbins, Jr. and the evolutionary synthesis (1924-1950)

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