MONTIA FONTANA L. 



seen under lens; under high magnification cells of surface more or less hexagonal, each 

 with a broad, blunt tubercle occupying most of the outer wall of cell (cells in centre 

 of plano-convex surfaces of seed rather larger and somewhat elongated); tubercles finely 

 papillose under microscope (high power). Plant usually tufted, yellowish- green, not 

 submerged, with short erect branches terminating in cymes. Habitat : light acid soils, 

 usually sandy or gravelly, with high water table at least in spring; only rarely more or 

 less submerged in water, and then much modified in habit. 



Distribution : Central and southern Europe; also Australia (see p. 6). The common, 

 and in some areas the only, subsp. in southern England ; rarer in N. England and Scotland. 

 V.c.'s: S, 1-3, 7, 9-12, 14-21, 26-30, 33, 34, 36-38, 40-43, 45, 46, 49, 52, 58, 61-63, 66, 

 69, 71, 77, 83-85, 95, 105. 



(3) subsp. intermedia (Beeby) comb. nov. 



M.fontana subsp. minor var. intermedia Beeby (1909), Ann. Scot. Nat. Hist., 

 104. 



M. lusitanica Sampaio (1912), Ann. Sc. Acad. Polyt. Porto, 7, (1) 52. 

 M. limosa Decker (1927), Verh. Bot. Vereins. Brandenburg, 69, 57. 

 M. rivularis, auct. mult., ? C.C. Gmelin. 



Ripe seed rather smaller than in the preceding sspp., 0-85 to 1-1 mm., finely tuberculate 

 at edge and rather shiny under lens, under higher magnification seen to have (2-) 3-4 (-5) 

 rows of cells on each side of keel bearing small but relatively narrow and high tubercles, 

 one in centre of each cell; tubercles finely papillose under high power of microscope; 

 cell-walls quite obvious, cells rather elongated. Plant usually loose in habit, often more 

 or less aquatic, with long bright green trailing branches bearing apparently axillary 

 cymes only. Habitat : as for subsp. fontana. 



Distribution : W., C. and S. Europe; also Australia (see p. 6). Common in W. England 

 and Wales; rare in Scotland. V.c.'s: S, 1-6, 8-11, 13, 14, 16-22, 24, 27, 30, 35-37, 39-49, 

 52, 54, 55, 57, 58, 60, 62-64, 66, 69-71, 88, 100. 



(4) subsp. variabilis subsp. nov. 



M. rivularis auct. mult., ? C. C. Gmel. 



A subsp. /ontand differt : semine maturo 0-9 — 1-1 mm. magis minusve piano minus 

 nitido quam in subsp. fontana, oculo valde armato tuberculis minimis varie evolutis 

 saepe humiUimis circa carinam praedito, seminibus maturis plantarum simul lectarum 

 saepe conspicue inter se dissimilibus. 



Typus in Herb. Univ. Cantab. : v.c. 45, Pembrokeshire; just north of Tedion Mt., 

 at edge of outlet from shallow pool, Martletwy, 22 June 1952, E. Milne- Redhead. 



Ripe seed 0-9 to 1-1 mm., more or less smooth (under lens) but not so shining as 

 subsp. /ontona; under higher magnification showing variable development of small usually 

 very low tubercles around keel, the variation often obvious between different ripe seeds 

 of same gathering. Plant usually loose in habit, resembling commonest forms of subsp. 

 intermedia, and found in similar habitats. 



Distribution : West and Central Europe ; elsewhere ? Locally common in N. England 

 and Wales, and occurring throughout the area where both subsp. fontana and subsp. 

 intermedia occur, but in certain districts (e.g. Isle of Man) the common and perhaps the 

 only subspecies. V.c.'s : 1-6, 9, 17, 30, 32, 35, 38-52, 55, 57, 59, 62, 64-66, 69-73, 

 75-77, 79, 83, 86, 88, 90, 91, 98-100, 108, 110. 



The seed sizes given in these descriptions are in each case the range of measurements 

 of * largest diameter ' made on three ripe seeds from each of four British gatherings. The 



