Highly variable populations of wild sunflower species were crossed with CMS cultivated lines. Variability was determined by measuring plant height and evaluating the type of branching. Mode of inheritance was tested by comparing the 27 hybrid populations against parents. Differences among parents in the observed traits were significant. All modes of inheritance for plant height were present in the F 1 generation. Heterosis was most frequent, followed in decreasing order by partial dominance,

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... inance and intermediacy. More than one mode of inheritance for plant height occurred because of the large variability in wild species and poligenic inheritance of the characteristic. All F 1 populations were fully branched, with or without the central head. The wild type of branching was found in F 1 because the wild parent dominated in genetic control of that trait over the cultivated one.