منابع مشابه
Aperture pattern ontogeny in angiosperms.
Pollen grains display a wide range of variation in aperture number and arrangement (pattern) in angiosperms. Apertures are well-defined areas of the pollen wall surface that permit pollen tube germination. For low aperture numbers, aperture patterns are characteristic of the major taxonomic divisions of angiosperms. This paper presents a developmental model that explains most of the aperture pa...
متن کاملAsymmetrical crossing barriers in angiosperms.
Patterns of reproductive isolation between species may provide insight into the mechanisms and evolution of barriers to interspecific gene exchange. We used data from published interspecific hybridization experiments from 14 genera of angiosperms in order to test for the presence of asymmetrical barriers to gene exchange. Reproductive isolation was examined at three life-history stages: the abi...
متن کاملBilirubin present in diverse angiosperms
BACKGROUND AND AIMS Bilirubin is an orange-yellow tetrapyrrole produced from the breakdown of heme by mammals and some other vertebrates. Plants, algae and cyanobacteria synthesize molecules similar to bilirubin, including the protein-bound bilins and phytochromobilin which harvest or sense light. Recently, we discovered bilirubin in the arils of Strelitzia nicolai, the White Bird of Paradise T...
متن کاملHydraulic conductances of angiosperms versus conifers: similar
because of slow growth rates caused by an inefficient transport system and low leaf photosynthetic capacity, gymnosperm seedlings are weak competitors with angiosperms in productive habitats. We measured component (shoot, leaf, and root) and whole-plant hydraulic conductances of sapling-sized tropical plants growing on nitrogen-poor white sand in Borneo. After accounting for size effects, there...
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ژورنال
عنوان ژورنال: Nature
سال: 1987
ISSN: 0028-0836,1476-4687
DOI: 10.1038/326750a0