THE WHITE WATERLILY OF IOWA 621 



THE WHITE WATERLILY OF IOWA. 

 HENRY S. CONARD. 



Most of the known species of waterlily (Nymphaea Sni.) are 

 extremely variable. The student feels obliged to recognize cer- 

 tain extreme forms as species. These are often restricted 

 geographically. But where their habitats are connected by 

 continuous land areas, the intermediate country is usually popu- 

 lated by a series of waterlilies which grade insensibly from one 

 extreme to the other. The commoner white waterlilies of North 

 America illustrate these conditions. 



The basic species in the United States is Nymphaea odorata 

 Ait. It is impossible sharply to demarcate Aiton's type form 

 from the smaller and pinker variety, designated by Pursh as 

 Nymphaea odorata var. rosea (commonly known as N. odorata 

 var. minor Sims). In the Atlantic coastal plain the variety 

 is the commoner form, from Nova Scotia to Delaware. At a 

 few isolated stations the whole flower is pink, giving the N. 

 odorata rosea of gardens. This plant may be designated as N. 

 odorata rosea forma rubra (cf. Rev. Hortieole 1881, p. 406). 

 From Delaware to Florida the var. gigantea Tricker is the com- 

 moner plant. The typical N. odorata is found in the New Eng- 

 land and Middle Atlantic states. The species ranges west- 

 ward to Minnesota, Nebraska, Missouri and probably to Arkan- 

 sas. Toward its western limits, however, it is much larger 

 and coarser than in the east. And it seems to be this coarse 

 form which runs on down into Mexico, and perhaps into Cuba 

 ami British Guiana. 



In the region from Lake Champlain to Lake Michigan, Nym- 

 phaea tuberosa Paine is found. The species was first described 

 from plants growing in central New York, and was so named 

 on account of the many easily detached, tuber-like branches 

 found on the rhizome. I have collected unmistakeable, though 

 miniature, specimens at Trenton, New Jersey, where they were 

 discovered by C. C. Abbott. This is the extreme southeastern 

 limit of the species. A kindred form, probably a hybrid with 



