2 



S. M. WALTERS 



A note by Hylander (1945) has done a great deal to clear the way to a solution of 

 the taxonomic problem; in this the author points out that Beeby's var. intermedia is (as 

 interpreted by Druce) at least in part identical with M. lusitanica Sampaio and refers 

 material from Cork with certainty to this species. 



Sampaio' s Montia lusitanica is adequately described and discussed by the author 

 (1912) who points out that the whole of the Montia material of Portugal is referable to 

 this single species, and that previous references to M. minor and M. rivularis in Portugal 

 were merely to habit-forms of extreme habitats (see below). He distinguishes his species 

 from ' M. minor, rivularis and lamprosperma ' basically on seed size and characters of 

 the seed-coat; and although the difference in size is certainly by no means so great or 

 so constant as he suggests (see below), the seed-coat character ' dense et acute tuber- 

 culatis ' is clearly stated. Apparently no type material was quoted, but I have seen 

 material determined by Sampaio (in Herb. Inst. G. Sampaio, Porto, by courtesy of the 

 Director), and there is no doubt as to the identity of this plant with var. intermedia Beeby. 



Decker (1927) described as a new species, M. limosa, a plant which he collected in 

 Brandenburg, Germany and was unable to refer either to M. minor or to * M. rivularis.' 

 There can be no doubt from his description that this new species is M. lusitanica; thus 

 he recognised it as distinct from the common M. minor of the district by the appearance 

 of its seeds under a lens - 'ihre scharf gekornelten, wenig glanzenden Samen.' Decker 

 suggests that Ascherson and Graebner's ' M. rivularis,' particularly records from the 

 N. German plain, is in large part his M. limosa. Compare also Lindberg's comments 

 (1901) on material determined as M. rivularis from C. Europe, from which it is clear 

 that he was aware of the somewhat intermediate nature of the seed type of Continental 

 * M. rivularis,' although he considered the differences - a rather shiny seed with smaller 

 tubercles - not sufficient to justify its separation from M, minor, and seemed to think 

 that even these seed differences are attributable to environmental modification. 



Comparison of herbarium material with ripe seeds soon confirms the view that 

 throughout N., W. and C. Europe the aggregate M. fontana is largely divisible into 

 three plants distinguished on seed type, and that over a considerable area, including 

 parts of England and much of N.W. Europe, two or all three types may occur together, 

 yet remain distinct. In total range, moreover, the three types show striking differences; 

 one (M. lamprosperma Cham.) is N. Temperate-Arctic and Alpine; one (M. minor auct.) 

 is Temperate European ; and the third, M. lusitanica, is W. European. 



If the morphological separation on seed type were more or less complete, it might 

 be taxonomically justifiable to treat the three as separate species. In fact, however, in 

 parts of northern England, and elsewhere in N.W. Europe, there occur plants whose ripe 

 seeds have small and somewhat variably developed tubercles, intermediate between 

 M. lusitanica and M. lamprosperma. Between M. verna and the other two, there are 

 in Britain and N.W. Europe as a whole apparently very few intermediate types, but 

 such seed types undoubtedly occur more frequently in the Mediterranean region. It 

 would seem best therefore to treat the aggregate as a single species, M. fontana L., with 

 geographical subspecies, viz.:- 



(1) subsp. fontana (M. lamprosperma Cham., the plant of the Linnean Herbarium). 

 *(2) subsp. chondrosperma (Fenzl) comb. nov. {M. fontana var. chondrosperma Fenzl 

 (1843) in Ledebour, Fl. Ross., 2, 152). 

 (3) subsp. intermedia (Beeby) comb. nov. (M. fontana var. intermedia Beeby, A^. 

 lusitanica Samp. M. limosa Decker). 

 Plants with seed type between that of (1) and (2) could be treated as the expected 



* I have, followed Mr. J. E. Dandy's advice in the matter of nomenclature of this subspecies. Neither M. lyrna Nock, nor 

 M, minor Gmel. is legitimate, both being rcnamings of M. fontana L. 



