306 University of California Publications in Botany [Vol. 5 



made up of long, narrow lobes ending in slender lanceolate tips pecu- 

 liar to angustifolia and the F^, bears no resemblance to the corolla 

 limb of sylvestris, in which the lobes are broadly triangular and the 

 lobing rarely extends over one-third the ^vay in from the margin. 

 The increased size of the F^ flower shown in the photograph, as con- 

 trasted with the flower of angustifolia to which it otherwise closely 

 corresponds, may again be assigned to the greatly increased expression 

 of all organs of the F^ as indicated in plate 38. It is even more sig- 

 nificant that the relation of length of tube to spread of limb in the 

 Fj corresponds closely to that displayed by angustifolia as contrasted 

 with the corresponding relation displayed by sylvestris. Flower color 

 in angustifolia is a very delicate shade of pink and, as contrasted with 

 the dead white of sylvestris, the F^ flower is hardly distinguishable 

 in color from its Tabacum parent. 



The domination in FiH3G of the particular Tabacum reaction 

 system concerned is nowhere more striking than in the case of leaf 

 characters. This point is brought out in plate 38 and treated spe- 

 cifically in plate 46. The long-petioled nature of the leaves of 

 angustifolia distinguishes this form sharply from the sessile-leaved 

 sylvestris as well as from the other Tabacum varieties, practically all 

 of which bear sessile, more or less auriculate leaves. The leaves of 

 angustifolia and of FjHSG in plate 46 were at the time selected to 

 show the peculiar extensions of the leaf-blade which, in the case of 

 the majority of the leaves of parent and hybrid, is decurrent along 

 only the upper half of the petiole. The dominance in the F^ of the 

 leaf -complex factors introduced by angustifolia is in the drawing too 

 distinct and comprehensive to require further comment here. One 

 should note, however, the presence in the F^ leaf of the rather long, 

 laterally curved point characteristic of angustifolia, for throughout 

 in the hybrids under discussion here the leaf-tip characters peculiar 

 to particular Tabacum varieties are remarkably reproduced in addi- 

 tion to more general characteristics of shape and form of leaf. 



F^HSS — N. Tabacum var. macrophylla X N. sylvestris 



This hybrid is figured in plate 39, figure 1, in plate 44, figure 1, 

 and in plate 47. It has throughout been one of the most striking of 

 the species hybrids under observation in our cultures. Its Tabacum 

 parent, macrophylla, as we have grown it, exhibits the lowest, most 

 diminutive habit (two to three feet) of any of the Tabacum varieties, 

 and thus by comparison F^HSS (six to seven and one-half feet) is 



