72 Species Hybrids of Digitalis 



The two species D. purpurea and D. (jrandiflora have recently been 

 hybridised by me at University College, Reading. The results of these 

 experiments form the subject of the present paper, before describing 

 vt'hich a short summary of previous references to the cross may be of 

 interest. For convenience D. purpurea and D. grandiflora will be, in 

 what follows, referred to as D.P. and D.G. 



Kolreuter failed to obtain viable seed as the result of crossing 

 D.P. and D.G., whichever species was used as seed-parent. 



Gartner obtained the hybrid {D.P. x D.G.) in quantity, but only a 

 single example of the reciprocal cross : he found both hybrids infertile' 

 and (D.P. x D.G.) the more like D.P.'' In another passage, however, he 

 says the latter hybrid resembles more the pollen-parent ^. 



Of the hybrid {D.P. x D.G.) he writes : " flowers somewhat shorter 

 than D.P., about 4 cm. long and 2-2 cm. broad, wider at the mouth. 

 Colour : pale red with a yellow tinge and with very pale, hardly notice- 

 able, irregular, confluent markings, especially in the under part of the 

 corolla." {D.G. x D.P.) is recorded as njore slender in growth and 

 showing a greater resemblance to D.P. Flowers 5 cm. long and 1 cm. 

 broad, of a pale purple colour, with externally a yellowish, internally 

 a pale purplish sheen. Numerous small dark purple spots were present. 



Godron also succeeded in obtaining the hybrid {D.G. x D.P.), which 

 he found fertile when pollinated by D.P. The resulting F.^ plants had 

 smallish, bright red flowers, while their leaves closely resembled those 

 of D.P. 



Focke found no difficulty in obtaining (D.P. x D.G.), but apparently 

 was unsuccessful with the reciprocal cross. In describing these hybrids 

 he says that in contrast to the case of {D.P. x D. lutea), the leaves here 

 show a considerable resemblance to those of D.P, The young leaves of 

 the hybrid are broad and downy but have no well-marked petiole. 

 The flowers are intermediate in size between those of D.P. and D.G. 

 The colour of the flowers is : " outside, a dull purple, paler on lower 

 side ; inside, paler purple with washed-out yellow reticulate markings 

 and having dark purple spots on lower side, each surrounded by a 

 yellowish-white halo." 



This description will be found to agree essentially with that given 

 below of this hybrid grown at Reading, where I have obtained plenty 

 of plants of {D.P. x D.G.), but only one of {D.G. x D.P.). There seems 

 no doubt therefore that it is much easier to effect this cross when D.P. 



1 Flor. (B.Z.) 1833, p. 365. - hoc. cit. pp. 288, 401. 



' hoc. cit. pp. 225, 226. 



