RIVER-SIDE FLOWERS. 373 



their bodies within the bladder and half out" (Darwin, 

 " Insectivorous Plants," pp. 405-406). 



The genus Utricularia has a calyx of two-leaved equal. 

 Corolla personate, spurred ; capsule globose, of one cell ; 

 named from utriculus, a little bladder. 



Utricularia vulgaris has the spur conical, upper lip as 

 long as the projecting palate, leaves pinnato-multifid. Roots 

 much branched, shooters or runners floating horizontally 

 in the water, clothed with capillary multifid leaves, bristly 

 at the margin, being little cristate bladders. Scape erect, 

 four to six inches high ; six or eight bright yellow flowers 

 in a raceme. Flowers June and July. 



Utricularia minor. Lesser Bladderwort, spur extremely 

 short ; upper lip as long as the palate, leaves subtripartite. 

 Vesicles mixed with the leaves, which latter are glabrous 

 at the margin. Flowers June and July. 



Utricularia intermedia. Very similar to the Vulgaris. 

 Flowers are smaller, of a paler yellow, and have a long 

 upper lip ; the flowers are more leafy, and the bladders 

 arise from branched stalks, not from the leaves. It is 

 more rare. Flowers June and July. 



There are fourteen British species of the POND-WEEDS, 

 Potamogeton (from the Greek words, potomos, a river, and 

 geiton, a neighbour), all growing in the water. Those 

 which are commonly found are the sharp-fruited and broad- 

 leaved pond-weed, P. natans; the fennel-leaved pond- weed, 

 P. peclinalis (Fig. in " E. B.," 1405) ; the grassy-leaved 

 pond-weed, P. gramineus (Fig. in " E. B.," 1406) ; the 

 curled-leaved pond-weed, P. Crispus (Fig. in " E. B.," 

 1413); the shining-leaved pond-weed, P. lucens (Fig. in 

 "E. B.," 1408). All these have their leaves linear or 

 lanceolate, and all grow under water. 



The BROAD-LEAVED POND-WEED (P. natans) Fig. in 

 " E. B.," 1399 has the leaves alternate, the upper ones 

 floating, broad and heart-shaped, with the flowering stem 

 between ; it is very common in stagnant waters and slow- 

 running rivers. The roots are eaten with great avidity by 

 swans. Mr. Stackhouse says : " Their love of this plant 

 is such, that a pair of them, by harassing it in search of its 



