120 



R. A. GRAHAM 



mint group, and would suggest its kinship to the M. cardiaca of the ancients as its more 

 correct status. 



(w) var. obscura Wimmer & Grabowski (1829, 178-9). 



Caule, calycihusque violaceo-purpurascentihus, foliis purpurascentibus vel viola- 

 scentibus, {Saepe caulis hirtus, folia subglaberrima complicata.) 



From the above description, this mint is undoubtedly a colour form, and it must 

 be regretfully pronounced that Fraser's description bears no resemblance whatsoever to 

 that of the original joint authors. 



This plant is classed as either a variety or a form under the authors* M. aquaiica 

 var. y gracilis, which is described as Foliis ovali-oblongis breviter petiolatis, caule elongate 

 sub-simplici, verticillis multis, capitulo parvo, which quite adequately describes M. X 

 gracilis Sole, or perhaps its var. cardiaca (Baker) Briquet { = M. cardiaca Ger., Baker, et 

 alior.), especially the strict, subspicate form (Graham 1950, 278). I do not know whether 

 their gracilis was the same sort of mint as Sole's but from the description it would appear 

 to be at least highly likely. Its place under M. aquatica L. is perhaps another example 

 of earlier authors believing a capitate and a verticillate mint to be essentially the same. 

 From the above evidence, var. obscura can scarcely be regarded as a variety of M. aquatica 

 L., but would appear to be a deeply-coloured form of M. X gracilis Sole, or of its var. 

 cardiaca. 



Summary 



Mentha aquatica L. should be regarded as one form only of an extremely polymorphic 

 group, known in the aggregate as Water Mint. Many forms have received distinctive 

 names, but their retention is not recommended on scientific grounds, as their existence 

 gives rise to a taxonomic chaos. Further, there would appear, according to present 

 knowledge, to be no justification on a etiological basis, though in this respect it is advisable 

 for more chromosome counts to be taken. So great is the range of variation in most 

 characters, and so gradual is any combination of characters, that all the named varieties 

 and forms should, in my view, be abandoned, and the whole group be regarded and 

 determined under the single binomial M. aquatica L., though for herbarium purposes 

 the different forms may, if desired, be separated under varietal names. Only one reser- 

 vation should be made, i.e. in respect of var. nemorosa Fr., correct assessment of which 

 must await the appearance of an original specimen. 



Acknowledgments 



I must express gratitude to the Curators of the Oxford and Cambridge University 

 herbaria, for kindly allowing their specimens of Water Mints to remain in my hands 

 during the final stages of complication of this paper. I am also greatly indebted to Dr. A. 

 Melderis, Mr. E. B. Bangerter, and other members of the staff of the British Museum, for 

 a tremendous amount of generous assistance; and to Dr. C. Baehni of the Geneva Conser- 

 vatoire for information. 



REFERENCES 



BAKER, J. G., 1865, On the English Mints, Journal of Botany, 3, 233-256. 

 BECKER, J., 1828. Flora der Gegend urn Frankfurt-am-Main, 1. 



BRAUN, H., 1890, Ueber einige Arten und Formen der Gattung Mentha, Verhandlung der Zoologisch- 



Botanischen Gesellschaft in Wein, 40, 351-507. 

 BRIQUET, J., 1891, Labiees Alpes Maritimes, 18-97. 



CAMUS, A. & E. G., 1911, Etude Botaniquc dcs Menthes Cultivces, Bulletin Scientifique et Industriel de 

 la Maison Roure-Bertrand Fils de Crasse, ser. 3, No. 4. 



