MINT NOTES 



By R. A. Graham 



V. Mentha aquatica, and the British Water Mints 



Water mints differ essentially from other British mint groups in having a capitate 

 inflorescence, the capitulum being borne terminally and with or without underlying, 

 axillary verticils. Rarely the inflorescence is very elongated to form a thick spike, the 

 contiguity of the underlying verticils contributing to such an appearance. Certain hybrids 

 of M. aquatica L. with M. spicata L. em. Huds., M. longifolia (L.) Huds. and M. arvensis 

 L. sometimes produce capitate forms, and these will be dealt with in papers on the res- 

 pective groups. 



M. aquatica L., 1753, Sp. PL, 1, 576 



Mentha floribus capitatis, foliis ovatis serratis petiolatis, staminibus corolla 

 longioribus . . . Planta non hirta, Verticilli terminales in capitulum s. spicam obtusam 

 conferti. 



There is, in my opinion, no Linnean specimen that can be satisfactorily accepted as 

 type or lectotype. Specimen No. 730/9 (Savage, 1945, Catalogue), which bears the name 

 aquatica in Linnaeus' hand, is one of those mint oddities whose exact status cannot be 

 ascertained without observation under cultivation, and cytogenetical investigation. 

 Undoubtedly it has some connection, through hybridity, with a water mint, and it agrees 

 with the description, in that (1) the stamens are exserted, and (2) that the inflorescence is 

 somewhat subspicate due to a close arrangement of the verticils, which are however far 

 more numerous {up to 10) than is usual in a water mint. From its general appearance, this 

 specimen is probably an unusual form of M. X verticillata L. (M. aquatica X arvensis). 

 Smith (1800, 198-9) considered it to be a connecting link between M. hirsuta Huds. and 

 M. paludosa Sole, and, believing it to represent the mint described as M. aquatica in 

 Sp. PL, he abandoned this binomial in favour of M. hirsuta to designate the water mint 

 group. There can, in my opinion, be no reasonable doubt that by M. aquatica, Linnaeus 

 intended the mint known to us as Water Mint, though to be sure he described a particular 

 form. His citations point to this, and, further, water mints grow quite commonly in 

 Sweden so that it is only reasonable to assume that Linnaeus knew them. This specimen 

 is best regarded as a misidentified oddity - several of the Linnean mints are queer plants. 



It is, perhaps, not strange that Linnaeus' description, being so short, agrees with the 

 specimen in certain respects. But I do not believe it to be the plant from which his 

 description was framed, and as this is of fundamental importance I give my reasons below 

 for rejection. 



(1) Linnaeus accurately describes a normal water mint, which has a capitate in- 

 florescence composed either of a terminal capitulum alone, or with underlying verticils 

 of which the uppermost one or two are contiguous or subcontiguous to the capitulum 

 thus giving the appearance of an obtuse spike. 



(2) The Linnean specimen is a verticillate mint. There is no capitulum, but an 

 apical verticil smaller than the many underlying verticils. There is thus no appearance 

 whatever of a capitate inflorescence, though it could be described as a spike or sub- 

 spike (but of very different appearance to the " spike " of a water mint). 



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