CERATOPHYLLACE^. (hORNWOKT FAMILY.) 419 



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

 cordate-ovate or oblong-ovate, acuminate ; spikes Avhite, terminal, nodding at 

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

 and muddy banks, Florida, and northward. May - August. — Rhizoma creep- 

 ing. Stem l°-::i° high. Spikes 4' - 6' long. 



2. PEPEROMIA, Ruiz&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. maguolisef 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 li'-3' long. 



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

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

 otherwise much like the preceding. (Piper leptostachyon, iVuW.) — Islands 

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



Order 116. CERATOPHYLLACE^E. (Hornwort 

 Family".) 



Submerged aquatic herbs, with filiform jointed branching stems, 

 finely dissected whorled leaves, and small axillary monoecious flow^ers, 

 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 o'viile. 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 wnrty ; 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' - 12' 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'- 12' 

 long. 



