L14 LYTHRACE^. 



phous. Ovary 2 3-celled; styles or stigmas 2 or 3, acute and 

 sessile. Fruit capsular, slightly pedicellate. Seeds numerous, 

 minute, without albumen. Herbaceous plants, with alternate 

 leaves, which are usually cut into capillary segments. Flowers 

 minute. 



POL>OSTEMUM. Mich. Podostemum. 



(From the Greek TTOVS ro<5oj, a foot, and ST^JJLOV, a stamen ; the stamens being 

 supported on a common footstalk.) 



Calyx and corolla none. Stamens 2, affixed to a common 

 pedicel Stigmas 2, sessile, recurved. Capsule 2-celled, 2- 

 valved, many-seeded. 



P. ceratophyllum Mich, : leaves dichotomously many-parted ; peduncles 

 solitary, axillary. 



Rocks in streams. N. Y. to Ala. July, Aug. (1). ? Stem creeping, 1 4 

 inches long, smooth, branching. Leaves alternate, crowded above. Flowers 

 axillary, on short fleshy peduncles. Horn-leaved Podostemum. 



ORDER XLVI. CERATOPHYLLACE^. HORNWORTS. 



Flowers monoecious. Calyx inferior, many-parted. STERILE 

 FL. Stamens 12 20; filaments wanting; anthers 2-celled. 

 FERTILE FL. Ovary 1-celled ; stigma filiform, oblique. Fruit 

 a beaked achenium. Seed pendulous, without albumen. 

 Floating herbs, with dichotomous cellular verticillate leaves. 

 Flowers small. 



CERATOPHYLLUM. Linn. Hornwort. 



(From the Greek iccpa?, a. horn, and ^uAXor, a leaf; the dichotomous leaves 

 resembling horns.) 



Character same as of the order. 



C. eckinatum Gray : achenium elliptic, slightly compressed, with 3 short 

 spines ; sides strongly muricated ; margins slightly winged, not gibbous, 

 armed with blunt teeth which finally become weak spines or horns as long 

 as the lateral spines. ( Torr. <$ (?r.) C. demersum (wholly or in part) of 

 American botanists. 



Ponds and slow-flowing streams. N. Y. to Virg. June, July. ^|-. Stem 

 submerged, branching, filiform, jointed. Leaves in numerous whorls of 6 8, 

 2 or 3-chotomously divided, the segments capillary. Flowers axillary, solitary, 

 sessile, very minute. Rough Hornwort. 



ORDER XLVII. LYTHRACE^E. LOOSESTRTFES. 



Sepals combined into a 4 7 -toothed calyx, the sinuses some- 

 times lengthened into other teeth or processes. Petals inserted 

 between the teeth of the calyx, sometimes wanting. Stamens 



