MONOECIA.— POLYANDRIA. 355 



HAB. In water. Aug. — Sept. U. Stem slend., 

 branch* ; leav. verticil, by 4'$, finely pectin, 

 i. M. verticillatum : leaves pinnate, capillary, upper 

 ones pectinate-pinnatifid ; flowers axillary, verti- 

 cillate, upper ones sterile, octandrous. 

 HAB. In water. July. U. Floating; upper f. 

 sometimes perfect. 

 3, M. heterophyllum: inferior leaves capillary-pinnate, 

 superior oval-lanceolate, acutely serrate ; flowers 

 hexandrous, the highest often perfect. 

 HAB. Lakes. July. H. Floating; stem simp,; 

 upper leav. in 5's and 6's ; Jl. purp. 

 1. M, capillaceum: leaves all capillarly-pinnate ; 

 flowers axillary, opposite, and alternate, te- 

 trandous, mostly perfect ; fruit quadrangular- 

 formed of 4 cylindrical seeds. 

 HAB. Ponds. July— Aug. U. Floating; stem 

 branch., dichot.; leaves hair-like, 

 .}. M. ambiguum : leaves petiolate, pinnate, the lowest 

 capillary, emerging ones pectinate, uppermost 

 nearly entire, subserrate ; flowers perfect ; an- 

 thers partly oblong ; fruit quadrangular. 

 HAB. Ponds. July. U. Floating, dichot.; leav. 



at ten. at base ; Jl. axill. solit. 

 p. limosum : stem rosting, erect, or procumbent ;- 

 leaves rigid, partly entire, or divided above, with 

 setaceous divisions. 

 HAB. Miry shores. July. U. Stem 1 — 4 in, 

 high ; leav. spread. ; seg. 3 — 5 ; anth. oblong. 

 i. M. tenellum : erect, nearly leafless ; bracts entire s 

 obtuse ; petals linear, conduplicate and revolute ; 

 flowers mostly perfect, tetrandrous. 

 HAB. Borders of ponds. July. ty. Stem simp,* 

 4 — 12 tin. high; Jl. alternate ; pet. oblong-lin, 



SAGITTAR1A. Arrowhead. Jancecc. 



'■-. S. sagittifolia : leaves sagittate, acute ; lobes acute 



straight, lanceolate. 

 ■:. latifolia: leaves broad-ovate, rather obtuse ; lobes 



ovate, slightly acuminate, straight. 

 3. hojtata : leaves oblong-lanceohte, acute ; lobe 1 



