ALBERT AND GABKIELLE HOWARD. 73 



every possible combination and in the 51 types described very few 

 of the flowers are alike in every particular. 



Unlike the types of X. rustica where the length of the 

 flower was practically constant and only the width varied, the 

 flowers of the types of X. tabacum show considerable diflerences 

 in length. The shortest flowers are found in type IX where the 

 length is 36 mm., the longest in type XI where the length is 

 50 mm. or more. The usual length of the flowers is about 

 45 mm. The colour is generally some shade of pink, but in some 

 types the pink colour is confined to the extreme tips of the corolla 

 lobes in the closed bud, the flower itself being quite white. In 

 many cases the pink colour fades and the older flowers are almost 

 or entirely white. In some types the pink colour is very deep 

 and practically does not fade at all (types XXX, XXXII 

 and XXXV). 



Calyx. The relative length of the cal^^x and corolla varies, 

 but the length of the calyx is always between one quarter to one 

 half that of the corolla. The gamosepalous calyx is not markedly 

 asymmetric and the teeth are generally somewhat long and acute. 

 In shape the calyx is generally tubular but in a few types {e.g., 

 XXXVIII, LI and others) it is distinctly globular and inflated. 



Corolla. Several diflerences in the form of the corolla may be 

 noticed. The orifice varies in size from a diameter of 7 mm. 

 (type I) to one of 11 mm. (type VII), but the usual width is 8 to 

 9 mm. The shape of the corolla (apart from the shape of the 

 limb) depends on the width of the tube, on the width of the 

 throat or dilated portion and on the manner of transition between 

 these two. The tube may be of various widths from the slender 

 tube in type XVI (Plate XVIII) to the broad tubes of types 

 XXXVIII and XLVII (Plates XL and XLVIII). The tube 

 may gradually dilate, giving the corolla a funnel-shaped appearance, 

 or there may be a sudden expansion in which case the corolla 

 appears " bell-shaped."' Good examples of bell-shaped corollas are 

 seen in plate XLV^III, types XLI and LI. The limb may be (1) 

 quite entire when it assumes a pentagonal shape (type XXXVIII, 

 Plate XL), (2) almost entire but slightly notched at the junction 



