192 THE WATERLILIES. 



as N. odorata maxima (N. tnbcrosa maxima (Hort.) Conard 1901 a) ; it has leaves 7 to 

 15 cm. in diameter; margin of leaf a little drawn in at the sinus; lobes overlapping; 

 angles acuminate. Petiole pubescent, with a few faint longitudinal stripes. Rhizome 

 somewhat tuberiferous. Flower medium to large, cup-shaped, with the fragrance of 

 N. odorata; sepals pure green outside, petals pure white like the type; rarely produces 

 seed. This may be a natural hybrid with N. odorata, since that species is common 

 in New Jersey, and Dr. Abbott has reported a diminutive but otherwise typical form 

 of N. tnbcrosa under the name of N. t. var. parva from near Trenton, N. J. 



A pink odorless waterlily found at Painesville, Ohio, may be a variety of this 

 (Beardslee 1877). 



Nymphaea tnbcrosa is a very strong grower ; when one wades among the plants, 

 great numbers of the tubers are detached, and float to the surface of the water ; thus 

 the plants are distributed and will in short time take complete possession of a small 

 pond. Gray ( 1889) speaks of the tubers as " spontaneously detaching " ; we have seen 

 no way for this to occur ; it seems more likely that they are naturally broken off by wad- 

 ing animals (deer, etc.) which feed on the leaves of Nymphaeas, as also by frogs, 

 turtles, and even by fish. 



At the margin of the astomatic area on the leaves, the stomata are large, oval or 

 round, and scattered, immersed in shallow pits ; those of the rest of the lamina are 

 small, round and crowded. Stomata are absent from a narrow margin all round the 

 leaf and along the sinus. 



Flower, June to September. Fruit, July to October. 



According to Robertson (1889) the flowers are visited by Hymenoptera : Andre- 

 nidae: (i) Agapostemon radiatns Say S; (2) A. nigricans F. ?; (3, 4) Halictus 

 S PP- ^! (5) H- pectoralis Sm. ?; (6) H. occidentalis Cress. ?; (7) H. coriaceus Sm. ?; 

 (8) P rosopis sp. ?. Diptera: Syrphidae: (9) Helophilus dizisus Lw. (10) H. lati- 

 frons Lw. Bombyliidae : ( 1 1 ) S porno polius fulvns Wied. Coleoptera : Rhipiphoridae : 

 (12) Rhipiphorus limbatus F. 



Subgenus 4. LOTOS, DECANDOLLE 1821 (in part). 



Flowers nocturnal, raised on stout peduncles 10 to 30 cm. above the water. 

 Sepals with 7 to 13 conspicuous and prominent veins. Stamens inserted at some dis- 

 tance above the petals, all flat and more or less ligulate, rounded at apex, dehiscing 

 simultaneously. Pollen smooth. Styles linear, ligulate. Leaves sinuate-dentate with 

 acute sub-spinous teeth. Petioles, peduncles, and under side of leaves more or less 

 pubescent. Main air-canals in peduncles 6 (5 to 7), in petioles 2; idioblasts and mul- 

 ticellular ingrowths absent. Rhizome tuberous, erect, ovoid, drying off in the resting 

 season. Seed rather small, with interrupted longitudinal lines of short hairs. Four 

 species native to the tropics of the Old World, from Senegambia to the Philippine 

 Islands, extending north to Hungary (two isolated localities) and south to Mada- 

 gascar. 



Lotos, Planchon 18536. Caspary 1865; 1888. 



Sec. II. Inapt'cndiculalac trib. I Lotos (in part) and trib. II Chamaclotos (in part), Lehmann 

 1853 a. 



