196 THE WATERLILIES. 



of the leaf, ramifying and anastomosing into a close reticulum, terminating in the 

 teeth of the leaf-margin; the midrib may project as a narrow ridge, 1.3 cm. high near 

 the petiole, becoming only 0.16 cm. high at apex, with sides perpendicular to the sur- 

 face of the leaf. Upper surface of leaf dark green and shining ; under surface green- 

 ish or dull purplish-brown, puberulent or rarely glabrous. Sinus open or with margins 

 slightly overlapping, rather shallow on account of the width of the peltation ; angles 

 formed by one of the dentations of the leaf. Petiole 60 to 160 cm. long, 0.6 to 1.3 cm. 

 in diameter, terete, usually pubescent, with a very strong " collar " at point of inser- 

 tion of the leaf, with two main air-canals placed transversely, two smaller canals ante- 

 riorly and posteriorly and a ring of 14 smaller ones surrounding the 6 just mentioned. 

 Stellate cells absent. Stipules present as a narrow transparent wing on either side of 

 the petiole at base. 



Tuber from seedling plant ovoid, roughened with small scattered leaf-scars below, 

 tapering to a point at the vegetative end, which is surrounded by long hairs. During 

 the growing season, stolons in every way similar to those of the germinating tuber in 

 shape and foliage are produced, along with short lateral buds on the caudex. At the 

 approach of the succeeding resting season, the old caudex dies, and the stolons and 

 buds ripen into rounded irregular tubers, smooth beneath and rough-hairy above, from 

 which the plant is easily propagated. During active vegetation the caudex is covered 

 closely by leaf-bases, is ovoid, 7 to 10 cm. long by 5 to 6 cm. thick. 



GEOGRAPHIC DISTRIBUTION. Egypt; central and west Africa. Senegambia, 

 Guinea, Madagascar. Grosswardein, Hungary. E. g. coll. Schweinfurth, Nov. 6, 

 1887, Damietta, Egypt. Coll. Haynald, Fl. exsicc. austro-hungar., No. 72, at Gross- 

 wardein. 



NOTES. The following species were set up, apparently on insufficient grounds: 

 N. dentata, white flowered, with narrow petals (width: length = i : 3.4), a purple spot 

 on upper part of inner filaments (and leaves glabrous beneath. Schum. & Thonn.) ; 

 the flower remains open until I p. m. Since the plant bearing this name in our gar- 

 dens has the leaves densely pubescent beneath, its identity with the type form col- 

 lected in Sierra Leone may be doubted. N. thcnnalis was separated from N. lotus 

 chiefly for geographical reasons, and named on account of its habitat, namely, the 

 hot springs of Grosswardein and Kaiserbade in Hungary. It has petals approaching 

 in shape those of TV. dentata, and is figured by Reichenbach (1845) as of a white color 

 tinged with purplish. 



The type form of the species was introduced into England from Egypt in 1802; 

 the dentata form was brought from Sierra Leone by one Mr. Whitfield in 1846, and 

 flowered first in that year (Hooker). 



The resting tubers and seeds are important articles of food in Egypt and West 

 Africa; the former are boiled, or roasted in the ashes of a fire, and are said to be 

 quite palatable; the latter are washed clean from the decaying carpels and arils, dried, 

 and ground into flour, from which a kind of bread is made. Both parts are very 

 rich in starch. 



In a plant of this species from Lake Nyassa, cultivated at Kcvv in 1886-88, 

 some, or later all, of the flowers were transformed into tubers, which dropped off 

 into the mud on the decay of the peduncle (Barber 1889). 



