8 EANUNCULACEAE 



perhaps not a more definite record than the one given by 

 Sibthorp in Flora Oxon. of 1794. It is quite possible that Merrett's 

 plant, which is here referred to R. Drouetii, may have been this 

 species. 



1. Isis. Near Eynsham. Bablock Hythe. Not uncommon in the 



still shallow waters of the Thames. In the Canal near 

 Shrivenham. 



2. Ock. South Hinksey. Ififley Meadows. Kennington. Abundant 



in the Canal between Abingdon and Wantage. In ponds 

 between Wantage Road Station and Steventon. Marcham. 



3. Pang. In the Thames near Streatley and Pangbourn. In the 



Pang near Pangbourn. Tilehurst. 



4. Kennet. Frequent in the Kennet Canal. In the moat at South- 



cote. In the Kennet at Newbury, Hungerford, &c. In Alder- 

 maston Lake. In the ponds at Hampstead Marshall. Benham. 

 Theale, &c. 



5. Loddon. Near Reading, Flower, 1. c. Near Sonning, Fudge. 



Thames near Park Place, Stanton. Loddon near Sandford, 

 Salmon. Medmenham, Melvill. Wargrave. Cookham. Arbor- 

 field, with a mud form in 1893. Windsor Great Park. Bray. 

 Ranunculus divaricatus appears to be a fairly constant species ; it 

 sometimes grows in running water with other species, but it still 

 keeps its peculiar habit. The dry summer of 1893 caused the water 

 in which it grew to evaporate, and it then assumed the mud form, the 

 var. terrestris of G-ren. & Godr. Fl. Fr. i. 25 ; it had much thicker, more 

 succulent leaves, but none were more conspicuously entire than the 

 rest. The flowers of R. divaricatus differ somewhat in size. In many 

 Water Buttercups the earlier flowers are larger than those produced 

 later in the season, but I have no notes as to whether this is the case 

 in the present species. One year, when a continuous rainfall took 

 place after the plant had begun blooming, so that the water level was 

 much above the flowers, the plant continued flowering and perfected 

 its fruit w^ithout completely opening its blossoms. The white ball- 

 like flowers looked rather peculiar against the dark foliage when seen 

 through a foot of water. This happened at Ferry Hinksey. 

 R. divaricatus is found in all the bordering counties. 



In adopting the specific name divaricatus^ which was proposed for the 

 plant in 1789, and which has been adopted by Ascherson {Fl. Brandenburg), 

 Grenier and Godron {Flore de France), Koch {Sgn. Fl. Germ.), and many 

 other botanists, the law of priority is followed though somewhat reluctantly. 

 Sibthorp's name was the first binominal appellation given to the plant in 

 Britain, and was taken from R. aquaticus alhus, circinatis tenuissime divisisfoUis 

 of Ray^ 8 Synopsis, ed. 3,249(1724); it is attached in Sibthorp's handwriting 

 to a specimen in the Sherardian Herbarium at Oxford. The oldest British 

 specimen with which I am acquainted is Bobart's in the Oxford Herbarium, 

 which was gathered probably near Oxford about 1680, and is labelled Mille- 



