398 CALLITRICHACEJi. ( WATER-STARWORT FAMILY.) 



1. SAURURUS, L LIZARD'S-TAIL. 



Stamens 4-8, with long club-shaped filaments. Fruit somewhat fleshy, com- 

 posed of 3 - 4 partly united 1 - 2-seeded carpels, pointed with as many stigmas. 

 Flowers white. 



1. S. cernuus, L. Stem erect, branching; leaves petioled, cordate-ovate, 

 or oblong-ovate, acuminate ; spikes white, terminal, nodding at the apex ; flow- 

 ers numerous, each from the axil of a small bract. Marshes and muddy banks, 

 Florida, and northward. May - Aug. Rhizoma creeping. Stem 1 - 2 high. 

 Spikes 4' -6' long. 



ORDER 116. CERATOPHYLLACE^. (HORNWORT 

 FAMILY.) 



Submerged aquatic herbs, with filiform jointed and branching stems, 

 finely dissected whorled leaves, and small axillary monoecious flowers, 

 destitute of floral envelopes, but surrounded by an involucre of 8-12 

 linear leaves. Anthers 1 2 - 24, oblong, 2 - 3-toothed, sessile. Ovary 

 solitary, simple, with a single suspended orthotropous ovule. Achenium 

 compressed, pointed with the slender persistent style. Albumen none. 

 Cotyledons 4. Plumule conspicuous. Consisting of the single genus 



1. CERATOPHYLLUM, L. HORNWORT. 



1 . C, demersum, L. Leaves rigid, 6 - 9 in a whorl, once or twice forking, 

 with the lobes spiny-toothed ; achenium oval, compressed, tubercular-roughened 

 on the sides, and armed near the base with 2 lateral widely-spreading slender 

 spines. In still water, Florida, and northward. Sept. and Oct. Stems 1- 

 4 long. Leaves near the end of the branches much crowded. 



2. C. echinatum, Gray? Leaves weak, 9-12 in a whorl, 3-4 times 

 forking, the ultimate segments bristly-toothed ; ovaries warty, unarmed ; ache- 

 nium oblong, tubercular-roughened on the sides, the edges margined and armed 

 with 5-7 strong and spreading spines. Shallow ponds, on St. Vincent's Isl- 

 and, West Florida. May. Stems 6' - 12' long. 



3. C. SU.brnersu.nl, L. Leaves hair-like, 3-4 times forking, bristlv- 

 toothed ; achenium oblong, slightly compressed, tubercular-roughened, with 

 rounded margins, unarmed. South Florida, Dr. Blodgett. Stems 6' -12' 

 long. 



ORDER 117. CALLITRICHACE^E. (WATER-STARWORT 

 FAMILY.) 



Small aquatic annuals, with opposite entire leaves, and solitary axillary 

 polygamous flowers without floral envelopes. Stamen mostly solitary, 2~ 

 bracted in the sterile flower. Filament slender : anther reniforni, the 



