1. Carpels free or (in Nelumbo) embeded in the receptacle; ovules solitary or 1 



to 3 in each carpel; stamens hypogynous, few to many (3 to 36) 

 and extrorse or slightly introrse, or very numerous and extrorse; 

 fruits leathery or hard, indehiscent; floating or emersed leaves pel- 

 tate and lacking a sinus (3) 



2(1). Perianth wide-spreading, composed of 4 sepals and 12 to 32 showy white, 

 pink, blue or yellow petals; carpels sunken in a cup-shaped fleshy 

 receptacle or hypanthium on the outer surface of which the petals 

 and stamens are inserted, prolonged upward into slender incurved 

 projections (carpellary styles) ; seeds arillate 1. Nymphaea 



2. Perianth subglobose, composed of 6 concave yellow (green- or red-tinged) 



sepals and numerous scalelike or stamenlike "petals" inserted with 

 the numerous stamens on the receptacle beneath the ovary; carpels 

 completely united, the stigmas radiate and sessile on a disk; seeds 

 not arillate 2. Nuphar 



3(1). Perianth of numerous segments, the flowers large and showy; receptacle 

 large, top-shaped, with the many uniovulate carpels sunken sepa- 

 rately in cavities on the upper side, only the stigmas protruding; 

 receptacle becoming enlarged greatly in fruit, the carpels maturing 

 into nuts; stamens very numerous, extrorse, hypogynous; all leaves 

 floating or emergent on strong petioles, centrally peltate, large, 

 glaucous; plants lacking mucilage 5. Nelumbo 



3. Perianth composed of 6 to 8 segments, the flowers small; receptacle small, with 



4 to 18 free superior carpels; fruit small, 1- to 3-seeded; leaves all 

 floating or submersed; plants more or less coated with mucilage (4) 



4(3). Plants with dissected opposite submersed leaves and small peltate floating 



leaves; perianth petaloid, white or purplish; stamens 3 to 6 



3. Cabomba 



4. Plants with only undivided alternate peltate floating leaves; sepals persistent, 



the petals dull-purple; stamens 18 to 36; plants heavily coated 

 (especially on lower leaf surface) with mucilage 4. Brasenia 



1. Nymphaea L. Water-lily. Water-nymph 



Plants with floating leaf blades and white, pink, blue or yellow flowers; leaves 

 subpeltate, cleft at the base; sepals 4, nearly free, spreading; petals few to many, 

 spreading, the inner petals passing into stamens, the outer petals about as large as 

 the sepals, all borne with the stamens on the hypanthium that encloses the ovary; 

 ovary 12- to 35-celled, the concave summit tipped by a globular projection at the 

 center around which are the radiate stigmas that project at the margin to extend 

 as linear and incurved sterile appendages; fruit depressed-globose, usually covered 

 with the persistent petal- and stamen-bases, maturing under water; seeds enveloped 

 by a saclike aril. 



About 50 species, widely dispersed in the tropics. 



1. Corolla yellow; rootstock stoloniferous at the apex 1. N. mexicana. 



1. Corolla white, pinkish, blue or violet; rootstock not stoloniferous (2) 



2(1). Flower raised on a peduncle above surface of water; corolla blue or violet; 

 outer stamens with the connective produced into an apical append- 

 age; carpels free at the sides; styles mere blunt protuberances 



2. N. elegans. 



2. Flowers floating; corolla white or pinkish; outer stamens not appendaged at 



the apex; carpels united at sides; styles subulate (3) 



3(2). Petals oblanceolate to subspatulate, widest above the middle, tapered at 



base but obtusely rounded at apex; rhizome branches tuberlike 



3. N. tuberosa. 



901 



