1 82 THE WATERLILIES. 



leaves are ovate, cordate, rounded at apex, with rounded basal lobes and sinus. Late 

 submerged leaves are sagittate-cordate, with deep narrow sinus; are stiff in texture, 

 bright emerald green, and stand erect or semi-erect, 1.12 to 1.42 cm. long by 0.8 to i.o 

 cm. wide. 



Leaf of mature plant nearly orbicular, fissi-cordate, never peltate, entire or 

 slightly emarginate at apex, 12 to 25 cm. in diameter, smooth and dark green above, 

 veins not evident; under side pustulate or spongy in appearance, smooth or slightly 

 pubescent ( ?) , varying in color from dark dull purplish-red to green tinged with 

 red in the lateral regions. Veins evident but not prominent beneath, the whole 

 lamina being thickened about them. Primary veins 8 to 9 on each side of leaf. 

 Length of principal area: length of radius of leaf =1:1.12 to 1.2 (=7.6 cm.: 8.6 

 cm.; =6.4:7.6 cm.). Depth of sinus less than one-half the length of the leaf 

 (1:2.5, average) ; margins straight or gently curved, touching, or spreading as much 

 as 30 ; angles obtuse, not at all produced. Petiole terete, slender, smooth or slightly 

 pubescent (always pubescent or hirsute when young, and at base in maturity), 30 to 

 180 cm. long, reddish-green to dark purplish-red, with 4 main air-canals and 2 to 4 

 smaller ones. Idioblasts very numerous, about 150 to 200 in central quadrangle one 

 centimeter below leaf; many bipolar idioblasts in the smaller intercellular spaces, and 

 a ring of thickened fibers around periphery. Stipules fused into a broadly wedge- 

 shaped, thin, white and semi-transparent scale, closely appressed to the rhizome, with 

 two-cleft apex and slightly decurrent, oblique base; outer surface pubescent, smooth 

 next to the rhizome; length 1.3 to 2 cm., width 1.2 to 1.4 cm.; bearing a shallow 

 rounded furrow next to the petiole, with 2 longitudinal sub-median keels, 0.3 cm. apart 

 beneath. 



Rhizome stout, 2.25 to 3.2 cm. thick and 30 to 100 cm. long, pale in color, covered 

 with a dense, short, black pubescence. Hairs of two types, one larger and stouter, of 

 comparatively short, iso-diametric cells, the others much more numerous, slender, 

 composed of few elongated cells ; all with 2 or 3 discoid basal cells. Interior dull white 

 with a pinkish tinge. Apex rounded, clothed with stipules and long fine hairs. Branches 

 stout, few in number, their attachment 1.3 to 2 cm. in diameter. 



GEOGRAPHIC DISTRIBUTION. Common in the Eastern United States; north to 

 Nova Scotia and Manitoba, south to Virginia and Arkansas. 



NOTES. Introduced into Europe (England) in 1786, by Win. Hamilton. In 

 1801 it was " far less common " there than N. cacntlca, and was considered a tender 

 plant; was well known in Europe in 1850; was cultivated in McMahon's garden 

 in Philadelphia in 1830 (Harshberger 1899), and appears in American trade-lists in 

 1883 and probably earlier. 



Flower from June to October ; fruit July to October. The roots were found to 

 be uninjured by drying away of the water in the fall at State College, Pa. (Buck- 

 hout 1891) ; the plant was also seen blooming well in the absence of water at Baury's 

 Lay, Buzzards Bay, R. I. (Sturtevant 1889). The plants which I have regarded as 

 types grow at Bristol, Pa., in a mill-pond. 



