398 CALLITRICHACE.E. (WATER-STARWORT FAMILY.) 



1. SAURURUS, L Lizard's-Tail. 



Stamens 4-8, with long dub-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 mnddy banks, 

 Florida, and northward. May -Aug. — Rhizoma creeping. Stem l°-2° high. 

 Spikes 4'- 6' long. 



Order 116. CERATOPHYLLACEiE. (ITornwort 

 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 ] 2 - 24, oblong, 2 - 3-toothed, sessile. Ovary 

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

 compressed, pointed Avith 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 Stillwater, Florida, and northward. Sept. and Oct. — Stems 1°- 

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



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

 forking, the ultimate segments bristly-toothed ; ovaries wart}', 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. M.ay. — Stems 6'- 12' long. 



3. C. SUbmerSUm, L. Leaves hair-like, 3-4 times forking, bristly- 

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

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

 long. 



Order 117. CALLITRICHACE^. (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 reniform, the 



