Breeding experiments which show that hybridisation and mutation etc. 217 



Pedigree 2. 

 Ancestors of the cross O. mut. viibHcalyjc. x O. grandifloi'a Q). 



riihricalyx (original mutant). 1907. 



rubricalyx (11) rubrinervis (l). 1908. grandiflora{-). 1908 



No. 070. 2 No. 40 



43 plants 



1 I ^ 1 



rubricalyx (33) rubrinervU (11). 1909. tall (38) dwarfs (5). 1909 



(32 in flower) (10 in flower) I I 



I I I 



No. IV. 8 X No. IV. 1 No. IV. 4 



(rubricalyx) L (grand/flora) | 



' 67 uniform rosettes I 23 dwarfs (ä). 191 o. 



red bud': green buds 



30 (in flower) 28 (in flower). 191 1. 



Y Y 



F2 families Fo families. 19 12. 



are very distinctive, the bud cone being slender, rounded, with thin 

 papery sepals which are either free from pubescence and papillae or 

 possess only a short, soft type of hair. The free sepal tips are also very 

 slender. The buds, therefore, like all other parts of the plant, are sharply 

 contrasted with rubricalyx in all their features. (See also Gates 1913 a, 



p. 38.) 



Let us now turn to the other parent, rubricalyx. It differs from 

 grandiflora throughout. The main features of contrast between the 

 two forms are set forth in table I (p. 227), but here I may refer to a 

 few of its characters and to its manner of origin. Fig. 8 shows a typical 

 rosette, fig. 10 the full-grown plant, and fig. 9 the buds two-thirds 

 natural size. (cf. figs. 2, 4 and 5 for grandiflora). The history of the 

 origin of rubricalyx has been published elsewhere (Gates 191 i b and 

 1912 b), but I will briefly state the main facts here. The original rubri- 

 calyx mutant appeared in my cultures of rubrinervis at the University 

 of Chicago in 1907, and I am indebted to Prof. John M. Coulter for 

 the facilities there afforded. 0. rubrinervis, it will be recalled, is a 



(1) See also Textfig. ) for collateral families of the rubricalyx parent. 



(2) Race No. 40 from Birkenhead. See text. ' 



(3) This was a uniform dwarf type 12 — 24 inches high, buds grandiflora, plants 

 irregularly branched. 



