Ellis, J. R., and Jules Janick. (Purdue U., Lafayette, Ind.) The chromosomes of Spinaeia oleracea. Amer. Jour. Bot. 47(3) : 210—214. Illus. 1960.—The somatic chromosomes of S. oleracea are described and each has been associated with one of the 6 morphological trisomics derived from triploid-diploid crosses. Of these 6 primary trisomies, reflex had been shown by genetic studies to be trisomic for the chromosomes carrying the sex-determining factors. This chromosome is the longest of the somatic complement and has a sub-median centromere. No obvious heteromorphism of this chromosome pair was observed in staminate plants. Heteromorphism involving this chromosome pair has been reported recently in 2 varieties of cultivated spinach by Zoschke (1956) and Dressier (1958) and was earlier reported by Araratjan (1939) for the wild species, S. tetandra. However, their accounts differ markedly from each other and with the present results in respect to the morphology of this chromosome pair. This study suggests the existence of races which differ with respect to the morphology of the chromosome pair containing the X Y factors.
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Ellis et al. (1960) studied this question.