14u tkr jouexal of botany 



The Ahgument as to Spots ox the Leayes. 



Most, if not all, P]aropean orchids with spotted leaves are some- 

 times found without spots. Even O. maculatciy which is perhaps 

 more persistently spotted than any other European orchid, occurs 

 Occasionally with unspotted leaves. Spots on the leaves are. not 

 therefore of specific value, and nothing seems to be known of their 

 cause or object. Our native mascula is sometimes spotted, sometimes 

 not. In 1918, I saw specimens with spotted leaves growing in the 

 midst of a colony of unspotted plants. As both kinds liourished 

 within the same square yard of ground, it was evident that soil and 

 surroundings had nothing to do with the spotting. Mr. H. McKechnie 

 suggested in the Keport of the Winchester College Nat. Hist. Soc. 

 (reprinted in Hep. B. E. C. (1917, p. 187) that ring-spotted latifolia 

 was originally a hybrid between maculata and prcetermissa, and 

 Mr. Druce (I. c. p. 167) regards it as proved that a plant with clear 

 green leaves crossed with one with spots of solid colour will produce 

 ringed spots in the offspring. This theory is so plausible that it 

 is apt to be too readily accepted. Is there any reason wh}'" the 

 circumference of the spot should retain its depth of colour, and the 

 centre revert to the original green of the leaf? Fewer or fainter 

 spots of solid colour would appear to be more truly intermediate. 

 Let us see what happens in the case of other orchids. On June 27th, 



1916, I found Oymnadenia conopsea X 0. maculata near Winchester, 

 the leaves were not spotted; another specimen found June 28th, 



1917, near Guildford, had spotted leaves, but the spots were solid. I 

 also found Coeloglossum viride X C. maculata near Winchester, the 

 leaves were spotted, the spots not ringed. Plate 15 {I. c), said to 

 be a form of the same hybrid, has unspotted leaves. O. incarnata is 

 unspotted, and so closely related to O. 'prceterinissa that nearly'' 

 all British botanists down to Hooker (and Mr. Druce himself 

 in the 14th ed. of Hayward's Botanist's Focket-hook (1914)), 

 considered it only a variet}^ of O. latifolia. We might therefore 

 expect that in its hybrids it would behave similarly to prcetermissa^ 

 O. incarnata X maculata, however, does not present ringed spots ; 

 according to Asch. & Graebner, and also to Schulze, it is either quite 

 unspotted or weakly spotted with faint spots. A specimen found at 

 Winchester in 1917 had all the leaves unspotted (plate 17, /. c). 



All this evidence goes to show that when spotted maculata is 

 crossed with an unspotted sj^ecies, whether the latter be O. conopseay 

 Codloglossum viride, or O. incarnata, the offspring is not ring-spotted ; 

 in all these cases the spots either disappear altogether or become 

 fewer and smaller, diminishing in intensity as a whole, not in the 

 centre ox\\y. Lastly, I have found several hybrids between O. prcBt-er- 

 missa itself and O. maculata. One from Godalming had the leaves 

 rather plentifully spotted; one from Winchester (I.e. plate 13) had 

 spotted leaves ; one from the Hog's Back had the lowest leaf 

 unspotted, the upper ones very clearly spotted with small irregular 

 spots. None of these had ring-spotted leaves. 



On the other hand, a hybrid between Conloglossum viride and 

 O. latifolia (ring-spotted), found at Winchester in June 1917,. had 



