EVOLUTION 17 



according to SchJechter (Mon. Orch. p. 158) certainly forming a genus of their own. 

 Orchis, Ophrys, Anacamptis and the continental Serapias have attained the apex of 

 evolutionary success. No new genera seem now to be in the making, evolution, as 

 far as European terrestrial orchids are concerned, being apparently now confined to 

 the expansion of existing genera. 



In Ophrys it seems as if the object in view has been to restrict the number of insect 

 visitors to an extraordinary degree. All the usual attractions, such as honey, potable 

 liquid, edible tissue, etc., have been discarded. The labeUum has been modified to 

 resemble the female of certain fossorial Hymenoptera, the males of which emerge 

 some time before the females, and carry out a furiously eager search for a possible 

 mate. Specialisation has been carried to such a degree as to mimic the females of 

 one particular genus, in the case of the N. African Ophrys speculum one particular 

 species. Die/is ciiiataJ In consequence insect visits are few, and limited not only to 

 the short time between the dates of emergence of the sexes, but to the males only, 

 and to the range of their wanderings from the ground where the females still he 

 in the pupa state, from which they do not venture far. 



Thus we see that Ophrys has gone considerably further in evolution than Orchis. 

 Instead of the two viscid discs being enclosed in a common pouch, each has a pouch 

 to itself, and a much higher degree of specialisation has been realised in its relation 

 to the insect world. 



The field of European orchids is too limited to illustrate all the steps in the path 

 of evolution. The lines of descent are nearly always parallel and quite independent. 

 While we can visualise a steady line of development through a succession of different 

 genera, which form as it were milestones, we cannot trace the multitudinous inter- 

 mediate steps. 



If Cephalanthera be taken as the starting-point of the evolution of the Monandras, 

 aU the genera fall into line in a natural order of progression. There is a steady march 

 of development from the simple to the complex. Nothing of this sort is perceptible, 

 when, as is usually the case, systematic works begin with Orchis, Ophrys, Serapias, or 

 Platanthera, which have respectively reached their highest point of evolutionary per- 

 fection. Cephalanthera, Epipactis, histera and i)!)/rtf«/Z»^j- are independent lines of descent, 

 but Neottia is identical with Lis f era in its floral mechanism. Each is the offspring 

 of a different conception. Goodyera, however, is a Spiranthes which has left that genus 

 behind by the development of its linear viscidium into a roughly quadrangular one — 

 a move in the direction of Himantoglossum — and the evolution of its pollinia into 

 separate packets of pollen tied together by elastic threads as in the Ophrydeje. It is 

 a change in the internal mechanism whilst the external facies remains that oi Spiranthes. 

 Goodyera seems to be the culminating point of the Spiranthes idea. 



' J-^- P- 33 (1925)- 



GBO J 



