ONAGRACKiE. 



1. P. PALU'STRIS. 



137 MyRlOPHYLLUM. 



Leaves linear-lanceolate, sharply serrate above the water, those below pin^ 

 natitid. Native in ditches and wet grounds. Root creeping ; stems a toot 

 high, roundish, with alternate, narrow, petioled leaves, their serratures very- 

 acute. If growing in water, the immersed leaves are pinnatifid with linear 

 segments. Flowers axillary, two or three togetlier, succeeded by a very hard, 

 bony, triangular nut. Jn. Jl. Spear-kuvcd Meniiald-wted. 



2. P. pectina'cea. 



Leaves all pinnatifid in a pectinate manner. Found in pools and ditches. 

 Considered by Michaux as P. palustris. Plants smaller than the preceding 

 species, flowering in July and August. Cut-leaved Mervudd-weed. 



9. MYRIOPHY'LLUM. 



Flowers monoecious, or frequently perfect. Sle.xileJI. — Ca- 

 ljx4-cleft; petals 4, caducous, frequently inconspicuous or 0; 

 stamens 4, 6 or 8. Fertile Ji. — Calyx 4-tODthed; petals 4 ; 

 stigmas 4, pubescent; styles 0; nuts 4, subglobose, 1-seeded. 



Gr. f^vQiOi. a myriad, and (^vXKov, a leaf; from the infinite number of the 

 divisions ol'the leaves. 



1. M. spica'tum. 



Leaves pinnate, capillary ; sfike terminal, interrupted, leafless, bearing the 

 flowers in whorls. A handsome aquatic, in deep water. Stem slender, branch- 

 ing, long and smooth. Leaves in whorls of 3 or 4, finely pectinate, with in- 

 numerable segments, always submerged. The spikes alone arise above the 

 water, with small whorls of green, sessile flowers. Jl. Aug. Per. 



Spiked U'uler-MUfuil. 



2. M. verticilla'tum. 



Leaves pinnate, capillar}', in whorls of about 3, upper ones pectinate-pin- 

 natifid ; fluicers in a.xillary whorls, upper ones sterile, octandrous. In stag- 

 nant waters. Stem long, rather slender, floating, the upper extremity in air, 

 with small green flowers. JL Per. Water Milfoil. 



3. M. tene'llum. 



Erect, leafless; bracts entire, obtuse; petals linear, conduplicate and revo- 

 lute. About the edges of ponds and rivers. Stems simple, 4-- 12 inches high, 

 bearing only b.i-acts and flowers. Flowers small, white, sessile, alternate, the 

 upper ones sterile. July. Per. 



4. M. heteropiiy'llum. 



Leaves in whorls of 5s, lower ones pinnately divided, with capillary seg- 

 ments, upper ones ovate-laijceolate, serrate, crowded. Stem thick, branching. 

 Petals oblong. Ovary ii- ridged. In sluggish waters. June — Sept. Leaves 

 very variable. 



5. M. ambi'guum. 



Stem dichotomous, floating; lower leaves capillary, middle ones pectinate, 



upper ones nearly entire, all petioled ; flowers mostly perfect ; carpels smooth. 



/3. limosum (M. procumbens. Bw.); 5/eMS procumbent and rooting; leaves 



M* 



