RELATIONSHIP OF TAXA IN GENUS MEDICAGO AS REVEALED BY HYBRIDIZATION. IV. M. HYBRIDA × M. SUFFRUTICOSA
Medicago hybrida Trautv. and M. suffruticosa Ram. are closely related, as indicated by their ease of hybridization, by the vigor and fertility of the F1, and by good pollen viability (94–98%) in the F1. In the F2, glandular hairs on pods vs. no-hairs segregated in a normal, 1:3 ratio; hairiness of M. suffruticosa was recessive to no-hair condition of M. hybrida. Coiling of pods was determined by six dominant, non-linked factors, A1–A6, with cumulative effect. M. suffruticosa possessed the dominant alleles. Neither M. hybrida nor M. suffruticosa could be hybridized with the M. sativa-falcata group, indicating their membership in different affinity groups. M. leiocarpa Benth. could be crossed with M. hybrida as well as with M. suffruticosa. Further study is needed to determine whether the M. hybrida-suffruticosa group belongs to the genus Medicago or Trigonella.