34 o THE WHEAT PLANT 



narrow spikelets containing two grains, and the empty glumes alike in 

 shape and texture. The wild plant has longer grains, and the conspicuous 

 fringe of silky hairs on the margins of the rachis is missing or much 

 reduced in the cultivated race. 



The fragile-eared Indo-Abyssinian forms exhibit the closest re- 

 semblance to the prototype, possessing, like the latter, easily disarticulated 

 ears, short culms, yellow-green foliage, and the remarkable anatomical 

 character of four to six vascular bundles in the coleoptile, as well as the 

 early habit. 



The European Emmers are a taller, later-ripening mutation, with 

 glaucous leaves, the usual pair of vascular bundles in the coleoptile, and 

 a fragile rachis. 



KHORASAN WHEAT (T. orientale, mihi) is a small race having pubescent 

 leaves, short almost solid culms, very lax ears, strong awns, long flinty 

 grain, and early habit, all of which characters are found in T. dicoccoides, 

 from which I consider it has originated. 



THE MACARONI WHEATS (T. durum, Desf.) exhibit obvious affinities 

 with T. dicoccoides and T. dicoccum, and I regard them as mutations derived 

 in some instances directly from the wild species, in others indirectly from 

 the latter by way of the cultivated Emmers. Like these the Macaroni 

 wheats possess solid culms, erect rigid ears with regularly arranged 

 spikelets, long, narrow, keeled glumes, and narrow, pointed grain ; many 

 forms also have a somewhat fragile rachis. 



The Indian examples of the race, particularly the Kathias of the 

 United Provinces, with their comparatively small ears and slightly hairy 

 leaf-blades, appear to have arisen from the Indo-Abyssinian group of 

 Emmers, the European durums, with their large, coarse ears, glabrous 

 leaves, and smooth-based awns, being derived from the large-eared, tall- 

 strawed European Emmers. 



POLISH WHEAT ( T. polonicum, L.), the most recent of the races of wheat, 

 I have no doubt is a mutation of T. durum, as first suggested in 1884 by 

 Beijerinck. Like T. durum, its leaves are glabrous, its straw tall, striate 

 and almost solid, and the grain long and flinty. Both are also similar in 

 habit, tillering capacity, and resistance to rusts. The only point of 

 difference, namely the excessively long, thin glumes, I regard as a heredi- 

 tary teratological variation. I have seen occasional specimens of Indian 

 durums with elongated glumes suggestive of incipient polonicum, and 

 Kornicke states that Schweinfurth sent him from Upper Egypt a transition 

 form between durum and polonicum. 



The lax ear, long spikelet, glumes, and grain of Khorasan wheat 

 (Race III.) suggest a variation towards the production of a polonicum 

 from the pubescent-leaved dicoccoides or Indo-Abyssinian dicoccum. 



