Results 131 to 140 of about 428 (163)
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Possible Early Pennsylvanian Ancestor of the Cycadales
Science, 1990A specimen of Lesleya , previously known only as isolated sterile foliage, has been found with two rows of ovule-bearing receptacles on opposite sides of the petiole. This specimen is from the Lower Pennsylvanian (Namurian B or C) of western Illinois.
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Maternal inheritance of plastids in Encephalartos Lehm. (Zamiaceae, Cycadales)
Genome, 2001The mode of inheritance of chloroplast DNA has been determined in Encephalartos by employing a restriction fragment length polymorphism analysis of chloroplast DNA. Artificial F1 hybrids were produced between a female specimen of E. natalensis and a male specimen of E. woodii.
CAFASSO D. +3 more
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Biflavonoids from the seed testa of cycadales
Phytochemistry, 1982Abstract Biflavonoid patterns from ethanolic extracts of the brightly coloured testa of eight species of Cycadales have been determined. Species from the genus Macrozamia are characterized by the occurrence of cupressuflavone- and amentoflavone-based patterns, while the Cycas species contain only amentoflavone-based patterns.
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COMPARATIVE POLLEN MORPHOLOGY AND TAXONOMIC AFFINITIES IN CYCADALES
American Journal of Botany, 1988Scanning and transmission electron microscopy of pollen grains of 29 species, representing the ten extant genera of Cycadales, has provided valuable insight into their relationships. Pollen grains of these taxa are boat‐shaped, monosulcate, and bilaterally symmetrical.
Bijan Dehgan, Nancy B. Dehgan
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New Jurassic protocycadalean ovuliphores and the origins of the Cycadales
Journal of Palaeosciences, 2004Ovuliferous spikes with two lateral rows of ovules are described from the Callovian of Georgia. The ovules are large, orthotropous, oblique to the stout rachis, with a scar of subtending bract at the base. They show a relatively thin integument and a bulky nucellus topped by a broad nucellar beak. This find constitutes a new genus Baruligyna gen.
Valentin A. Krassilov, Maya P. Doludenko
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Seed Coat Anatomy of Ceratozamia mexicana (Cycadales)
The Botanical Review, 2004I. Abstract The seed coat furnishes protection with a thick cuticle, tannin cells, mucilage, and a hard sclerotesta. The external layer of the seed coat is a sarcotesta; a thick cuticle covers the external walls of its epidermal cells. This epidermis bears stomates and, in the early stages, trichomes. The subepidermal cells have druses.
María Ydelia Sánchez–Tinoco +1 more
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ORIGIN AND ACTIVITY OF SUCCESSIVE CAMBIA IN CYCAS (CYCADALES)
American Journal of Botany, 1991Observations of the vascular tissue of Cycas shoots have provided supporting evidence that the first vascular cambium as well as subsequent successive cambia are simultaneously active. The establishment of the second cambium occurs during the seedling stage, and differentiates mainly within the cortical cells.
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An Overview of Cycadales in Mesoamerica and the Caribbean:
2022Michael Calonje +2 more
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Cycadales of the English Wealden
Monographs of the Palaeontographical Society, 2004Joan Watson +3 more
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