336 THE JOURNAL OF BOTANY 



LIMOSELLA AQUATICA L. var. TENUIFOLIA Hook. f. 



By W. p. Hiern, M.A. 



(Plate 426 C.) 



An interesting form of Mudwort was collected last June and 

 July at Kenfig Pool, Glamorganshire, by the Kev. E. S. Marshall 

 and Mr. W. A. Shoolbred, each of whom is of opinion that it is a 

 species abundantly distinct from Lim.osella aquatica L. This opinion 

 accords with the views taken by many botanists, as appears from 

 the synonymy ; but, on the other hand, the matured judgement of 

 other botanists, and a comparison of specimens in our larger her- 

 baria, lead to the conclusion that the form ought to be considered 

 a mere variety. The chief points of difference that are alleged to 

 characterize it are two : first, the ca^spitose habit, with complete 

 absence of stolons ; and, secondly, the subulate shape of the leaves, 

 without any dilated blade. 



The presence or absence of runners cannot be used as a character 

 for this or other allied forms, since both states occur in all of them, 

 and, in fact, some of our specimens are stoloniferous ; also the 

 breadth of the leaf- blade is so variable, and specimens show such a 

 close gradation down to its total evanescence, that it is quite im- 

 practicable to employ its absence, either with or without other 

 characters, for a serviceable diagnosis. 



The name and synonymy of the plant are as follows : — 



LiMosELLA AQUATICA L. Sp. PI. p. 631 (1753), var. temdfolia 

 Hook. f. Fl. Antarct. ii. p. 334 (1846 ?) ; Reichenb. Ic. Fl. Germ. 

 XX. p. 54, t. MDccxxii. fig. ii. and iii. (1862). 



L. tenuifolia Wolf ex Hoflm. Deutschl. Fl. ed. 2, i. ii. p. 29 



(1804) ? ; Nuttall in Journ. Acad. Nat. Sc. Philad. i. 1, No. 6 



(Oct. 1817), p. 115. 

 L. diau'lra Krocker, Fl. Siles. ii. p. 406 (1790), partly ; non L. 



(1771). 

 L, aiistndis R. Br. Prodr. Fl. Nov. Holl. p. 443 (1810), partly. 

 L. aquatica (3 hifiora Wahlenb. Fl. Lapp. p. 171 (1812), partly. 

 L. subulata Ives in Trans. Med.-Phys. Soc. New York, p. 440 



(1817). 

 L. aquatica [3 diandra Hartm. Handl. Skand. Fl. p. 241 (1820), 



partly. 

 L, borealis Lessing, Reise Norw. p. 299 (1831), partly. 

 L. aquatica var. minor Hartm. Handl. Skand. Fl. ed. 3, p. 146 



(1838), partly. 

 L. aquatica var. borealis Hartm. I.e. ed. 9, p. 56 (1864), partly. 



Sir Joseph Hooker, /. c, adds the following note : — " I am con- 

 vinced there is no specific distinctness between the Limosella aquatica 

 L. and L. tenuifolia Nutt., and have consequently united them. In 

 the specimens from the southern hemisphere which I have examined, 

 the leaves do not attain the breadth which those of the northern 

 temperate regions generally present; though, on the other hand, 



