338 THE WHEAT PLANT 



T. dicoccum has both immune and susceptible varieties. At Reading 

 the Indo- Abyssinian Emmers are slightly susceptible to rusts, the Russian 

 and Serbian forms more resistant, the late-ripening European repre- 

 sentatives being immune. 



From a study of " serum " reactions Zade placed T. dicoccum, T. 

 durum, T. polonicum in one class, T. vulgare, T. compactum, and T. Spelta 

 in another, T. monococcum being distinct from these, and the results of 

 Sakamura's investigations into the chromosome number of the several 

 races suggests a similar grouping. 



There is, I think, no doubt that the classification of the races of wheat 

 into (i) Small Spelt, (2) Emmer, and (3) Dinkel or Bread Wheat series, 

 supported as it is by so many independent lines of research, indicates in 

 a broad way their genetic affinities. 



In regard to the phylogenetic relationship of the several races of 

 wheat, my investigations have led me to formulate the scheme given on 



P- 339- 



So far as concerns the races which are included in the three series 



and the prototypes of two of them, it is in substantial agreement with 

 the conclusions of Schulz, Flaksberger, and others ; it differs, however, 

 in the view taken of the origin and relationship of the Bread Wheat 

 series. 



The evidence upon which the scheme is based is discussed later. 



SERIES I. The Small Spelt series includes the wild T. aegilopoides , 

 Bal., and the cultivated T. monococcum, L. 



Even from a cursory glance at the mature plants the relationship 

 between the wild T. aegilopoides and the cultivated J 1 . monococcum is 

 evident. 



In all morphological characters of the culm, ear, glumes, and grain 

 there is little or no difference between the two, the only modification 

 being a reduction in the hairs on the leaves and rachis. 



Hybrids of T. monococcum with wheats of the dicoccum and vulgare 

 series are quite sterile, and the results of the determination of the chromo- 

 some number, immunity to rusts, and the " serum " reactions strikingly 

 support the conclusion that this series is distinct from the rest of the 

 cultivated wheats. 



SERIES II. The Emmer series comprises the Wild Emmer (T. her- 

 monis, Cook) and the cultivated Emmer, Khorasan, Macaroni, 

 Polish, Rivet, and Egyptian Cone wheats. 



THE CULTIVATED EMMER WHEATS (T. dicoccum, Schiibl.) constitute 

 an ancient race agreeing closely in almost all its characters with the wild 

 T. dicoccoides. In both, the hairs on the surface of the leaf-blades are 

 similar in form, length, and arrangement ; the ears also are flat, with 



