850 naiadace^:. 



Ponds and streams, common. Aug. Stem long and slender, and with the leaves 

 floating. Leaves when floating, elongated, narrow, and pellucid. 



Order 114. NAIADACEJE.— Pondicced Family. 



Immersed aquatic plants, with jointed stems and sheathing stipules within the pe- 

 tioles, or sessile sheathing bases, inconspicuous mono-diozcious flowers, which are naked 

 or with a free merely scale-like cahja. Stamens definite. Oyarie3 1, or 2 to 4, free, 

 1-ovuled. Stigma simple, often sessile. Flowers usually bursting from a spathe. 

 Fruit dry, indehiscent, 1-celled, 1-seeded. 



1. NAIAS, Linn. Naiad. 



Gr. Xaias, water-nymph ; from the habitat. 



Flowers dioecious, or sometimes monoecious, axillary, 

 solitary and sessile. Fertile flowers consisting of a 

 single ovary tapering into a short style ; stigmas 2 to 4, awl- 

 shaped. Stamens 1, with a slender filament. Fruit a 

 little seed-like nutlet, enclosed in a loose epicarp. — Slender 

 branching herbs, growing entirely under water, with opposite and 

 whorled crowed linear leaves, sessile and dilated at the base, and very 

 small flowers, solitary, but often clustered with the branch-leaves in 

 the axils. 



1. N. flexilis, Rostk. Bending Water Nymph. 



Leaves membranaceous, spreading, narrowly linear, very minutely denticulate, 

 opposite or in 3s, 4s or 6b at the joints ; stigmasusvi&lly 3 to i. (S. Canadensis, Michr. 

 Caulinia, Wild.) 



Ponds and slow streams, common. July— Sept. Stem 6 to 20 inches long, many 

 times forked. Leaves % to 1 inch long, lets than 1 line wide. Flowers very small, 

 sessile. 



2. N. minor, L. Smaller Water Nymph. 



Leaves alternate or opposite, linear-subulate, recurved, prickly-toothed, rigid. 

 In water, not common. Aug. Stem long, submersed, rathar rigid. Flowert 

 small. 



2. ZANNICHELLIA, Mitchell. Horned Pondweed, 



In honor of Zannichelli, a Tenitian botanist. 



Flowers monoecious, sessile, naked, usually both kinds 

 from the same axil; the sterile consisting of a single stamen, 

 with a slender filament; the fertile of 2 to 5 (mostly 4) 

 sessile pistils in a cup-shaped involucre. Stigma large and 

 peltate. Fruit a nutled, on a short stipe, beaked with a 

 short style. — S 7 ender branching herbs, growing entirely under 

 water, with very slender stems opposite or alternate long and 

 linear thread-form entire kaves } and sheathing membraneous 

 stipules, 



