The ultrastructure of root nodules of Elaeagnus conferta Roxb. and the activities of nitrogen fixation and hydrogen uptake were studied, The results show that Frankia hyphae exist at early stage in intercellular space in nodule cortex. The filamentous hyphae are branched with septa. Lipid bodies are distributed in infected young cells. The number of infected cells in mature nodules is much larger than that of young and senescent nodules. Apical endophytic hyphae swell to form lots of vesicles which are septate and double-walled. Vesicles are suggested to be importatant in nitrogen fixation. In senescent nodules, the vesicles disintegrate. Nitrogen fixation and hydrogen uptake activities in mature nodule is much higher than that in young and senescent nodules.
