CLASSIFICATION 159 



its appearance in this country that plants belonging to varieties differing 

 only in the colour of the awn cannot be accurately classified except after 

 observations extending over two or three seasons at least. 



Grain colour is a hereditary character subject to little variation and 

 usually determined without much trouble. Only in Macaroni Wheats 

 is it sometimes extremely difficult to distinguish the pale red flinty grains 

 from those which are white with yellowish translucent endosperm. 



The amount and character of the hair on the glumes is of good 

 diagnostic value and in most cases is readily seen. Care, however, is 

 needed where the hair is short and sparsely distributed. 



FORM. Wheats belonging to the same variety as defined by reference 

 to the scheme just mentioned differ among themselves in the length of 

 the ear and straw, the density of the ear, the shape of the empty glumes, 

 the earliness and lateness of ripening, and in other hereditary features 

 both morphological and physiological. For example, the variety of 

 T. vulgare with beardless ears, white glabrous chaff, and red grain (var. 

 lutescens) includes the wheats known among farmers as Purple straw, 

 Red Fife, Squarehead, Briquet Jaune, Warden, and many others. 



These names represent, or ought to represent, the progeny of a single 

 individual, the origin of which may, or may not, be known with certainty. 

 To each of these I apply the term /orm, in place of the terms variety, 

 type, or sort used by others. 



Many attempts have been made to group these forms for purposes of 

 easy reference and identification, but none of the various schemes pro- 

 posed are of more than limited application. 



In the case of the rarer varieties in which only a small number of forms 

 are known the task is not insuperable, and simple keys for the identifica- 

 tion of the several forms may be readily devised ; but in the varieties 

 erythrospermum (bearded ears, with white glabrous glumes and red grain), 

 ftrrugineitm (bearded ears, with red glabrous glumes and red grain), 

 lutescens, and milturum (the corresponding beardless varieties) of T. 

 vulgare, and in lesser degree the varieties leucurum (ears with white 

 glabrous glumes and white grain) and hurdeiforme (ears with red glabrous 

 glumes and white grain) of '/'. Jurum, the existing forms are so numerous 

 and intergradc in almost all their characters between one extreme and 

 another that the formation of clearly defined groups or classes is a problem 

 of the greatest difficulty, if not practically impossible. 



The most useful way of dealing with such extensive varieties is to make 

 a separate classification for the forms of it cultivated in each country 

 In order to accomplish this, and for purposes of identification of the 

 separate forms, detailed descriptions are needed. These should be made- 

 after a study of the living plants grown side by side during several seasons 

 and should take cognisance of the following characters : 



