2003 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 90 (2003). 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.

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Cover Illustration V90.1: A snap trap of the Venus's flytrap, Dionaea muscipula Ellis ex L. (Droseraceae), native in North America forms a sister group with widely distributed aquatic snap trap species Aldrovanda vesiculosa L. Image credit: Mitsuyasu Hasebe. Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see Rivadavia et al.: Phylogeny of the sundews, Drosera (Droseraceae), based on chloroplast rbcL and nuclear 18S ribosomal DNA sequences

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Cover Illustration V90.2: Monophyllaea horsfieldii R.Br., cultivated at the Botanical Garden Vienna (HBV), grown from seeds collected by Dr. Kwiton Jong at Batu Caves, Selangor, West Malaysia. The plant represents a giant seedling, with the stem corresponding to the hypocotyl and the single leaf to an enormously enlarged cotyledon. As flowers and fruits are produced in the seedling stage, Monophyllaea provides a perfect example of neoteny in the plant kingdom. The genus belongs to the morphologically and biogeographically noteworthy tribe Epithemateae of Gesneriaceae. Image credit: A. Weber. Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see Mayer et al.: Phylogenetic position and generic differentiation of Epithemateae (Gesneriaceae) inferred from plastid DNA sequence data

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Cover Illustration V90.3: Artibeus lituratus, the great fruit bat, feeding on the infructescences of Cecropia sp. Species of Artibeus are important dispersers of Cecropia. Morphological and anatomical study has revealed that the dispersal unit of Cecropia is the entire fruit, not just the seed. Bats consume the fleshy floral parts surrounding the fruits and disperse the fruits. Image credit: Merlin D. Tuttle. Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see Lobova et al.: Cecropia as a food resource for bats in French Guiana and the significance of fruit structure in seed dispersal and longevity

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Cover Illustration V90.4: Asplenium aureum Cav. photographed in a remnant of laurel forest in the Barranco del Laurel, Gran Canaria. This species is endemic to the Canary Islands and is the largest within subgenus Ceterach. Molecular data suggest the polyphyly of subgenus Ceterach (Willd.) Bir et al., implicating homoplasy in the lamina shape and the dense scale cover, characters previously used to circumscribe this group. Image credit: Ronald Viane. Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see Van den heede et al.:Phylogenetic analysis of Aspleniumsub genus Ceterach (Pteridophyta: Aspleniaceae) based on plastid and nuclear ribosomal ITS DNA sequences


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Cover Illustration V90.5: Pollen germination and tube growth in the snow buttercup, Ranunculus adoneus, photographed under fluorescence microscopy. Snow buttercup flowers exhibit heliotropism, the capacity to track the sun's rays over the course of the day. The adaptive significance of solar tracking in snow buttercups is mediated through the impact of flower heliotropism on paternal and maternal floral environments. In controlled crosses, pollen from solar-tracking flowers has higher germination success than pollen from experimentally restrained flowers. Solar tracking in recipient flowers also enhances pollen germination and increases pollen tube to ovule ratios. Image credit: C. Galen. Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see Galen and Stanton: Sunny- side up: flower heliotropism as a source of parental environmental effects on pollen quality and performance in the snow buttercup, Ranunculus adoneus (Ranunculaceae)

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Cover Illustration V90.6: Cross section through the dehisced anther of Xylopia collina of the pawpaw family (Annonaceae). Species of the genus Xylopia, as well as other members of this family, produce large pollen that is shed in units of four or sometimes even 32 grains (some tetrads visible in illustration). Associated with these compound pollen units in most genera are layers of sterile tissue, called septa, that separate the grains into chambers within each anther. Tsou and Johnson investigated the variation and development of the septa of Annonaceae, and found that despite variability in appearance, the septal tissues of all species were formed by the same developmental pathway. They propose that these tissues may have evolved in Annonaceae in response to a requirement for extra nutrients and support tissues for large pollen units. Image credit: C.-H. Tsou. Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see Tsou and Johnson: Comparative development of aspetate and septate anthers of Annonaceae

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Cover Illustration V90.7: Agroxiphium sandwicense subsp. macrocephalum, photographed on the Silversword Loop Trail in Haleakala National Park, Maui, Hawaii. The silverswords in Haleakala National Park grow in the largest number on these cinder cones in the caldera of Haleakala, but since goats have been removed from the National Park, silverswords are colonizing other areas of alpine lava. See Crawford: Everything known about tarweeds and silverswords, plus much, much more, Photo credit: Sherwin Carlquist (1966). Link to larger JPEG of the image


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Cover Illustration V90.8: A severe infestation of Lygodium microphyllum (Cav.) R. Br. located at Jonathan Dickinson State Park, Martin County, Florida, USA. A native of the Old World tropics, L. microphyllum has become a serious pest in the forested wetlands of South Florida since naturalizing in the 1960s. Within severe infestations, this vine-like fern can smother both the understory and canopy, disrupting the recruitment of native vegetation and altering local fire ecology. The spread of this species appears to be facilitated by its ability to reproduce via intragametophytic selfing. Image credit: M. Lott. Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see Lott et al.: The reproductive biology of the invasive ferns Lygodium microphyllum and L. japonicum (Schizaeaceae): implications for invasive potential

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Cover Illustration V90.9: Rare fossil twig with attached leaves and flowers of Pseudosalix handleyi, a newly recognized genus and species of the Salicaceae from the Eocene Green River Formation of northeastern Utah. Although similar to Salix in leaf architecture, unisexual flowers, and capsular fruits, this plant differs by its branched inflorescences and well-developed perianth. The fossil is interpreted to belong within the family Salicaceae s.l., as the immediate sister group to the clade containing extant Salix and Populus. Image credit: Steven Manchester. Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see Boucher et al.: An extinct genus of Salicaceae based on twigs with attached flowers, fruits, and foliage from the Eocene Green River Formation of Utah and Colorado


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Cover Illustration V90.10: The three most abundant Venezuelan columnar cacti, from left to right, Pilosocereus lanuginosus (Linnaeus) Byles & Rowley, Stenocereus griseus (Haworth) Buxbaum, and Cereus repandus (Linnaeus) Miller. These species depend strictly on nectar-feeding bats for their pollination. Bat-mediated gene dispersal confers high levels of genetic exchange among populations of the three species, a process that enhances levels of genetic diversity within their populations. Image credit: Janet Castro. Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see Nassar et al.: Population genetic structure of Venezuelan chiropterophilous columnar cacti (Cactaceae)


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Cover Illustration V90.11: The golden heads of Balsamorhiza and Wyethia covering the foothills herald spring in Utah's Wasatch Mountains. Balsamorhiza macrophylla, the cutleat balsamroot (shown here), commonly grows interspersed with B. sagittata (arrowleaf balsamroot) and W. amplexicaulis (mule's ear) on hillsides and in open woods.Photo taken in Red Butte Canyon, Salt Lake City, Utah, USA. Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see Moore and Bohs: An ITS phylogeny of Balsamorhiza and Wyethia (Asteraceae: Heliantheae)

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Cover Illustration V90.12: A phylogeny of angiosperms based on matK, a plastid gene nested within the trnK intron. Illustrations are superimposed on photographs of representative taxa from major angiosperm lineages, with Amborella shown in the center. We thank Peter K. Endress for providing photographs of Chloranthus and Ceratophyllum, Porter P. Lowry II for Amborella, and Duncan M. Porter for Tiarella (Saxifragaceae). Link to larger JPEG of the image

Link to the American Journal of Botany abstract for the related article, see Khidir W. Hilu et al.: Angiosperm phylogeny based on <011>matK sequence information

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