THE GENUS POLIANTHES. 



603 



THE GENUS POLIANTHES (INCLUDING PEOOHNYANTHES 



AND BEAVOA). 



By A. WOESLEY. 



Authors who have treated these three genera as distinct from each 

 other have merely copied these names from earher writers, but without 

 demonstrating that any sufficient distinctions exist to support the 

 retention of three distinct genera. Of recent years hybridists have 

 shown, in at least two cases, that members of these alleged genera can 

 be crossed as easily as though they were species of but one genus. 



In 1894 Prochnyanthes Bulliana (Bot, Mag. 7427) was crossed, in 

 the Eoyal Gardens, Kew, with Bravoa geminifiora, which cross pro- 

 duced, in 1899, the hybrid named Bravoa x kewensis {Gard, Chron.^ 

 Aug. 1889, p. 112). This hybrid holds an intermediate position between 

 the parent species in some of its characters, but in general it inclines 

 towards the female parent in the ratio of 2 to 1. It is fertile to its own 

 pollen. 



In 1903, 1905, and 1906 Mr. Bhss, in his garden at Orpington, 

 crossed Bravoa geminifiora with a garden form of Polianthes tuberosa, 

 which cross produced, in 1907, the hybrid Polianthes x Blissii herein- 

 after described. This hybrid is also fertile to its own pollen. 



The three genera have therefore all been crossed inter se, and have 

 produced in addition fertile hybrids, which clearly shows that they 

 should all be included in one genus, to which the old Linnean name of 

 Polianthes must be given. 



Whenever foreign pollen has been used, it is well known that the 

 paucity and infertility of the resulting seed is a true gauge of the 

 remoteness or comparative irreconcilability of the parents. In such 

 cases the pollen is not altogether suitable for fertilizing the ovules— 

 some difficulty has to be overcome at the very start; and hence few 

 ovules are fertilized, few seeds result, and much of what looks like 

 seed proves infertile. On the other hand, when we find that the 

 normal quantity of seed is produced, and that germination is good, 

 we then know that the parents belong to the same genus. Now Mr. 

 Bliss obtained conclusive results in 1906. On that occasion he pol- 

 linated five flowers of B. geminifiora with the pollen of P. tuberosa, 

 and three fruits were produced, containing twenty-eight, twenty-one, 

 and eighteen seeds respectively. Of these sixty-seven seeds no less 

 than fifty-two grew up. This one fact is quite conclusive of the near 

 relationship of the parents. 



The hybrid P. x Blissii takes four months to ripen its seed. Its 

 fruit is larger and its seed more shining than is the case with 



*Ilos6 and others have already transferred B. geminifiora with other species to 

 Polianthes on morphological grounds. 



