buttish mapsk okchtds 243 



THE BRITISH MAKSH ORCHIDS IN RELATION TO 

 MENDELIAN PRINCIPLES *. 



Bi' Rey. T. Stephenson, D.D., and T. A. Stephenson, M.Sc. 



The brief discussion here presented is by way of introduction to 

 a forthcoming paper on the groups of Orcliis latifolia L. The 

 present tendency is to deny that the species occurs in Britain at all, 

 whilst at the same time conceding that probably it does occur on the 

 Continent. Our own impression is that a very similar set of forms 

 exists in both cases, only much more complex in the greater area. 

 Pending critical experiments, it will do no harm to explore some of 

 the possible conditions of the problem. As a good deal of work is 

 being done at the present time in this group, we may at once refer 

 to some of the most recent papers. In the Reports of the Winchester 

 College Natural History Society for 1910-PJ17, and in j^receding 

 issues, there are some excellent records and discussions, together with 

 several photographs of interesting types : the forms dealt with all 

 grow near Winchester, and many exceedingly' interesting hybrids are 

 described. Independently of Dr. Druce, a type of unspotted Marsh 

 Orchis was separated as a second form of O. incarnata, which now 

 has the rank of a species as O. prcetermissa (Druce). The Botanical 

 Exchange Club Reports for some years past have devoted much 

 attention to the group : the 1917 Report contains a review of the 

 Marsh Orchids, by Dr. Druce, who also summarizes the Winchester 

 Reports. In these Reports are full discussions of the species founded 

 b\^Dr. Druce — namely O. lyt'cetermissa, O. ¥uchsii'\,'d\\i\ O. O'XrI/t/i, 

 as well as some new varieties. In the Orchid JRevieiv for July 1918 

 (xxvi. IGli) Mr. Rolfe has written upon the whole group, and in 

 Sept.-Dec. 1919 a list of natural hybrids is given. In this Journal 

 for 1919 (187-142), Col. Godfery\vrites on "The Problem of the 

 British Marsh Orchids " ; his knowledge of Continental species makes 

 his observations of much value. Research in this group owes very 

 much to Dr. Druce, who has probably examined Marsh Orchids in si/ if 

 in almost every county of the British Isles : the present writers cannot 

 claim such wide experience, and are glad to acknowledge a great debt 

 to his published work and to assistance })rivately given. 



Col. Godfery presents two general hypotheses of the relations of 

 the Marsh Orchids : (1) that there are only two main species, namely 

 O. incarnata and O. prceterniissa, the rest being hybrids of these 

 species with forms of O. maculaia ; (2) that there are three main 

 species, namely the two just mentioned and ring-spotted O. laiij'olia. 

 In this case, Reckoning O. Fucliaii as distinct from O. (riceiorum, 

 nine hybrid varieties are possible, not i-eckoning O. Fuchsiix O. eri- 

 cetorum (=0. trausiens Druce). We decidedly prefer the second 

 alternative, only we by no means think that O. latifolia necessarily 



* Owing- to an unavoidable delay in the printing of the Plate illustrating the 

 species of Orchis, the present paper appears out of its due order. 



t N.B.— We are using the names O. Fuchsii Druce and 0. ericetorxim Linton 

 for t'.ie sake oi' clearness, to distinguish the two British groups of Spotted Orchids : 

 by O. maculatii L. we indicate the aggregate species. 



