76 Sjyecies Hybrids of Digitalis 



{D.G. X D.P.) is a greenish-cream (very much ligliter than in D.G.) with 

 pale rose flush above, also with spots (Plate IV, fig. 7). In neither 

 hybrid are the brown markings characteristic of D.O. apparent. 



5. The shapes of the corolla tubes in the hybrids also show a 

 preponderant influence of the female parent (see Plate IV). 



6. The anthers of all e.xcept D.G. have dark purple .spots; the 

 spots in the hybrids, however, are smaller and less numerous than 

 in D.P. 



Calyx. In all the four forms of Digitalis under consideration the 

 sepals are of three sizes ; the upper being the smallest, the two lower 

 laterals largest, and the two upper laterals intermediate in size. 



7. Comparing now corresponding sepals of these plants : those of 

 D.P. are large, broad and ovate and have numerous, conspicuous veins 

 raised above the surface (text-fig. 5) : those of the other species D.G. 

 ai'e small and narrow with few, very inconspicuous veins not raised 

 above the surface, lateral branchings being quite invisible in the fresh 

 green sepals (text-fig. 6). 



The sepals of the two hybrids are intermediate in every particular, 

 but differ from one another in that {D.P. x D.G.) (text-fig. 7) is nearer 

 the D.P. type as regards shape and veiuing than is {D.G. x D.P.) (text- 

 fig. 8). In this latter, the sepals tend to be almost the same width 

 throughout their length, instead of narrowing gradually towards their 

 bases. 



8. The way in which the sepals of any one flower are united is also 

 characteristic : in D.P. and {D.P. x D.G.) the members of the calyx 

 overlap one another in the fully opened flower (text-figs. 1 and 3), 

 while in D.G. and {D.G. x D.P.) gaps occur between them (text-figs. 2 

 and 4). 



9. The nature of the multicellular hairs on the calyces is also 

 worth notice. In D.P. the hairs are long, slender and of two kinds, viz. 

 with pointed end-cells and rounded end-cells (text- figs. 17 and IS). 



In D.G. the hairs are all of one kind — short, stout and with rounded 

 end-cells (text-fig. 19). 



In the hybrids the hairs are intermediate in size and all have 

 rounded end-cells (text-figs. 20 and 21), there being no very noticeable 

 difference between the reciprocals. 



This distinction in size and structure of the hairs was not found to 

 hold in the case of the ordinary foliage leaves, on which the hairs are of 

 different character and common to all four types of plants. 



