SPECIES CROSSES IN THE GENUS NICOTIANA. 205 



Q.— STERILE HYBRIDS. 



N. tabacum x glauca. (Plates 18 and 19.) 



Though intermediate in many respects, this plant is, in my 

 opinion, considerably more like N. tabacum than N. glauca. 

 In one point — the annual as opposed to perennial duration — 

 the character of N. tabacum may be said to be fully dominant. 

 And the shape and texture of the leaves and general habit of 

 the plant as grown in the open decidedly recall N. tabacum. 

 These characters are entirely different fro ma the same features of 

 N. glauca as shown by plants which I was able to grow in the 

 open air in Ceylon tlie year following the growth of the hybrids. 

 In every detail of shape and structure, however, so far as my 

 observation went, there were small differences from the taba- 

 cum type, which were clearly referable to the glauca parent. 

 Thus in the flowers the red pigment of tabacum only partly 

 obscured the yellow pigment of glauca, botli these colours 

 being therefore dominant (though probably both reduced in 

 amount as compared with either parent — a point I had no 

 means of estimating accurately). The leaves were more 

 markedly stalked than those of N. tabacum, and the bases of 

 the young leaves showed a pigmentation like the same parts 

 in N. glauca, but paler and redder in tint. The form of the 

 inflorescence and the shape of the flowers also show obvious 

 influences from the glauca parent. Both in the open and 

 under glass all the flowers fell off without producing fruits. 



According to Focke, Naudin obtained two examples of the 

 cross N. (tabacum angustifolium X glauca) X tabacum 

 macrophyllum. One of these plants closely resembled the 

 primary hybrid and the other resembled N. tab. macro- 

 phyllum. This statement strongly suggests segregation. 



N. acutiflora x alata (hybrid). (Plate 20.) 



N. acutiflora has very long narrow leaves and flowers, the 

 corolla being a pale yellowish white. The leaves are greatly 

 undulated, and the whole plant is very scabrous, being covered 

 with stiff, hooked, multicellular bristles. 



The pollen parent was one of the recently produced coloured 

 garden hybrids of N. alata with N. forgetiana, but showed 



