Erroneous determinations of chromosome configurations in (grandiflora X lamarckiana) acuens[center dot]gaudens and truncans[center dot]gaudens were detected because the original determinations were incompatible with the segmental interchange theory. A regrowing of this material and reexamination of its chromosome behavior resulted in findings compatible with this theory: acuens[center dot]gaudens has [image] 12, 1 pair; truncans[center dot]gaudens has [image] 14. The new determinations make it possible to complete the segmental arrangement of acuens, as follows: 1[center dot]4 3[center dot]2 5[center dot]6 7[center dot]10 9[center dot]8 11[center dot]12 13[center dot]14.