HYBRIDISM VS. SELECTION 



By F. W. Burbidge, Curator, Trinity College Botanical Gardens, Dublin, Ireland 



Hybrids are of two descriptions, those produced naturally or spontan- 

 eously in the wilds, and those raised artificially in the garden, but there is 

 no real distinction between them. We are told that a hybrid is the off- 

 spring o£ two species, one or both of which at times may be either pollen or 

 seed parent. But the dav of a rigid belief in "pure species" of plants is 

 past, and to say any plant is a species, simply means the expression of one's 

 own, or somebody else's, judgment or opinion. A species is merely some 

 botanist's decision, and not nature's decision, for how can nature be decided, 

 seeing that evolution is continually going on? A species often includes an 

 enormous number of individual plants varying more or less among them- 

 selves, and which come more or less true from seed. A species is, in fact, 

 often a very variable quantity, and its capacity for variation is absolutely 

 unknown, except as it is experimented upon in the garden or elsewhere. Our 

 ignorance of the natural history of plants is profound. Two so-called species 

 grow in the same soil and situation, and belong to the same natural group 

 or order, and yet while one is a useful food plant, the other is a virulent 

 poison to men or other animals. 



Again, two plants called species, may grow on the Andes or Himalayas 

 side by side, and yet, when brought to American or European gardens, the 

 one may be quite hardy, while the other dies unless sheltered in an artificial 

 temperature. Why plants thus vary in their secretions or products, and in 

 hardihood, no one knows ; that they do so is a fact patent to the most 

 ordinary observer, and these problems await solution from the biologists of 

 the future. 



Again, two related species will, when hybridized together, sometimes 

 produce fertile offspring, and in other cases barren ones. Sometimes 

 species A will fertilize species B, but species B will not fertilize species A, 

 but why, no one knows. In other cases, two or more species will be recip- 

 rocally fertile, but why this is so, neither physicist nor physiologist can say. 

 any more than they can tell us why one plant secretes or makes sugar and 

 another starch, and others wine and oil — nutritious food — healing medicines 

 or deadly poisons. These so far are the secrets of nature's great laboratory. 



But let us come to the hybrid. The whole history of hybrids is obscure, 

 and in many cases the so-called records are most unreliable. In the case of 

 so-called spontaneous or wild hybrids what has happened is this : The arm- 

 chair botanist, knowing nothing of the circumstances of their origin or 

 native environment, has simply named and described them as pure species I 

 Now and then, as in the case of some orchids, a guess as to their parentage 



