REVIEWS, BOOK NOTICES, ETC. 187 



by Mr. Hiern ; ^ so that the treatment of the species may be noticed, 

 and especially of the varieties and forms, which it seems difficult to 

 keep to any standard. For example, Ca//itriche, a genus very difficult 

 to diagnose without fruit, has distributed among its species no less 

 than twelve, exclusive of the normal forms. As one who has culti- 

 vated these plants, I do not believe they will stand the test ; they 

 are simply individual variation, ever reverting to their original type. 



Mr. Williams uses the genus Fra7igula Tour, iox Rhamnus Frangula 

 L. as F. alnus Miller, giving reasons for so doing. For Linum 

 perenne L. he uses Z. anglicum Miller ; his reasoning here seems to 

 lend itself to the alteration. For L. angicstifolium Huds. (1778) we 

 have L. hispanicnm Miller (1768). We are told that Erodium 

 cicutarium Alton has no varieties in Britain ; to this some will demur. 

 In some cases the distribution given seems hardly full enough, i.e. 

 C. maritimum Aiton. 



In the genus Callitriche we have C. platycarpa as a species apart 

 from C. stagfmlis, with five named varieties, etc., under them. 

 Hegelmaier in his monograph ^ combined them, but he kept 

 C. pediinculata DC. as a species. 



C. angustifolia Hoppe is kept as a species separated from C. 

 intermedia Hoff. Certainly this has some characters that seem to 

 commend this, but they require testing by cultivation, and the 

 majority of Continental authors place it under C. vertia L. seg. 

 Under one of these he remarks (p. 509), "The difference in form 

 between the floating leaves and the lower leaves is very marked " ; 

 but surely this is only a passing state. I believe it to be impossible 

 to separate these plants by leaves alone, except in the second 

 section {i.e. truncata and aiitiimnalis). 



He keeps up C. pedunculata DC. as a species, and observes, " It 

 is interesting from the fact that it forms its fruit in early summer." 

 But this is simply because the water is evaporated earlier and the 

 plants exposed to more sun, and within a few yards C. obtusangula 

 Le Gall, (submerged) may be found in good fruit at the same time. 



C. verna he quotes as of Withering, " Bot. An. Veg. Brit.," p. 2, 

 1776, as C. verna \,. has no meaning. But is Withering's description 

 (quoted) enough to determine this ? 



C. autumnalis L. (October i 755) is replaced by C. Jiertnaphroditica, 

 Juslenius, "Cent. Plant.," n. 89, p. 31 (February 1755), whose 

 description consists of five words ; but I suppose Haller's reference 

 must be accepted. 



The distribution of this species is of interest in relation to 

 C. truncata Guss. It extends from Shetland ! south to Anglesea ! 

 and Cheshire ! (53"' 16 N. lat.), while truncata extends north to 

 Nottinghamshire at 53°'26', so they slightly overlap. The record of 

 " Devon S." in " Topi. Botany " is probably an error, but it may have 

 been truncata not then separated in Britain. 



C. polymorpha Lbnn. Mr. Williams passes with scant notice : his 



1 "Jour, of Botany," p. 229, 1909. 



2 " Mon. Gatt. Callitriche," 1864. 



