II RANUNCULACEiE 55 



excite sympathy. It is in some respects an intermediate 

 form between the land and water species of the genus, 

 as the achenes are only sliglitly wrinkled and furrowed. 

 It grows on muddy banks, often extending into the 

 water. The stem is thick and hollow. The submerged 

 foliage differs from the aerial, and more nearly resembles 

 that of the aquatic species. The flowers are small and 

 pale yellow, the petals scarcely longer than the sepals, 

 which are reflexed. There is no scale over the nectary. 

 The carpels are small, in a dense head which gradually 

 becomes oblong. As an annual it can easily establish 

 itself wherever a suitable situation offers. The species 

 is spread over Europe and temperate Asia, as far south 

 as Bengal. It appears to be visited almost exclusively 

 by Diptera (flies). M. Vesque has made the interesting 

 observation that if it is grown in damp air the stoma ta 

 become more numerous, and appear on the upper as 

 well as on the lower sides of the leaves. 



R. Lingua.— This, which is our largest species, grows 

 to a height of 3 or 4 feet, and has beautiful golden- 

 yellow flowers, some 2 inches in diameter, in a loose 

 panicle. It lives on the edges of lakes and in shallow 

 water. The stem is erect, stout, and hollow. The 

 upper aerial leaves are long, lanceolate, and entire, or 

 with a few small teeth. It has thus adopted one of 

 the forms so characteristic of water plants. The lower 

 submerged leaves are cordate, broad, and obtuse. The 

 flowers are protogynous. At the base of each petal is 

 a large nectary, which secretes a copious supply of honey. 

 Fertilisation is almost exclusively due to flies. Since 

 the anthers open towards the outside of the flower, and 

 also bend outwards as they mature, self-fertilisation is 

 difiicult, though not impossible, owing to the oblique 

 position of the flower ; it seems to have but little effect. 

 The plant is common in the temperate parts of Europe 

 and Asia. 



R. Flammula somewhat resembles R. Lingua, but is 

 much smaller and slenderer, with decumbent, rooting 

 stems. It is sometimes hairy and sometimes glabrous. 



