CLASS XXI. ORDER VIII. 371 



Erect, leafless; bractes entire, obtuse; petals lin- 

 ear, condiiplicate and revolute. 



Root creeping. Stem simple, erect, four to twelve inches 

 high, round, smooth, leafless. Flowers alternate, sessile, with 

 oblong-obovate, obtuse, concave bractes, twice as long as the 

 flower. Calyx leaves very short, acute. Petals while, oblong- 

 linear, obtuse, three times as long as the calyx, doubled back- 

 ward and afterward revolute. Stamens in the upper flowers, 

 erect, as long as the petals ; anthers oblong. Germs in the lower 

 flowers, four, adnate; stigmas four, persistent, recurved, pubes- 

 cent, becoming feathery. Capsules four, growing together. — la 

 the edge of Fresh pond, also at Tewksbury and Plymouth. It is 

 sometimes quite out of water and is then very small. — July. — 

 Perennial. 



* Myriophyllum procumbens. Dwarf MyriopliylJum. 



M. caiile procwnbente ; fol'us pinnatifidis, subsexfi- 

 dis ; Jioribus axillaribus, soliiariis, sessilibus. 



Stem procumbent ; leaves pinnatifid, about six 

 cleft; flowers axillary, solitary, sessile. 



Stem slender, round, flexuous, rooting, branched. Leaves 

 alternate, pinnatifid, with five or six narrow, fleshy segments ; 

 the lower ones sometimes linear. Flowers axillary, solitary, ses- 

 sile. Calyx segments four, oblong, concave. Anthers four, ob- 

 long. Germs four, oblong, tapering upward; stigmas curving 

 outwardly. — July. 



This minute plant grows upon the mud about ponds, and was 

 first sent to me from Danvers by Dr. Nichols. A specimen 

 which Dr. Boott received from the herbarium of Michaux, 

 marked "M. scabraium,^^ resembled this nearly, except in being 

 somewhat larger. Mr. Nuttall's M. limosum is perhaps a variety. 



3S5. CERATOPHYLLUM. 



Ceratophyllum echinatum. Gray. liornwort. 



Fruit elliptical, slightly compressed, with three 



short spines, strongly muricated ; margins armed 



with blunt teeth, which finally become weak spines. 



