CERATOPHYLLACfiJE. (HORXWORT FAMILY.) 419 



1. S. cernuus, L. Stem erect, branching ; leaves alternate, petioled, 

 Cordate-ovate or obloiig-ovate, acuminate ; spikes white, terminal, nodding at 

 the apex ; flowers numerous, each from the axil of a small bract. Marshes 

 ami muddy banks, Florida, and northward. May - August. Khizoma creep- 

 ing. Stem l-2 high. Spikes 4' - 6' long. 



2. PEPEROMIA, Kuiz&Pavon. 



Stamens 2, short, lateral. Anthers extrorse. Stigma capitate. Fruit 

 baccate, 1 -celled, 1 -seeded. Herbs, with alternate or whorled leaves, and 

 filiform spikes of small crowded peltate-bracted flowers. 



1 . P. magnolisef Olia, C. DC. Leaves mostly alternate, rigid, petioled, 

 obovate, pellucid-punctate; spikes terminal, densely flowered, longer than the 

 leaves ; peduncles as long as the petiole ; bracts rounded. East Florida. 

 Leaves l'-3' long. 



2. P. leptOStachya, Chapm. Leaves opposite or whorled, very thin, 

 smaller ( 1' or less long), 3-uerved ; spikes very slender, rather loosely flowered ; 

 otherwise much like the preceding. (Piper leptostachyoii, Nutt.) Islands 

 at the mouth of the St. John's River, Florida ( Curtiss). 



ORDER 116. CERATOPHYLLACE^E. (HORNWORT 



FAMILY.) 



Submerged aquatic herbs, with filiform jointed 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 12-24, oblong, 2-3-toothed, sessile. Ovary 

 solitary, simple, with a single suspended orthotropous ovule. Ache- 

 nium 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 spread- 

 ing slender spines. In still water, Florida, and northward. Sept. - Oct. 

 Stems l-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 ; achenium ob- 

 long, tubercular-roughened on the sides, the edges margined and armed with 

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

 West Florida. May. Stems 6' - 1 2' long. 



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

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

 rounded margins unarmed. South Florida Dr. Blodgett. Stems 6' - 1 2' 

 long. 



