HALORAGEiE. ( WATER-MILFOIL FAMILY.) 175 



* Stamens 8 : petals deciduous: carpels even: leaves whorled in threes or fours. 



1. M. spicatum, L. Leaves all pinnately parted and capillary, except 

 the floral ones or bracts; these ovate, entire or toothed, and chiefly shorter than tht 

 flowers, which thus form an interrupted spike. — Deep water: common. (Eu.J 



2. M. verticillatum, L. Floral leaves much longer than the flowers, pec- 

 tinate-pinnatijid : otherwise nearly as No. 1. — Ponds, &c. northward. (Eu.) 



# * Stamens 4 : petals rather persistent : carpels 1 - 2-ridged and roughened on the 



back: leaves whorled in fours and Jives, the lower with capillary divisions. 



3. M. heterophyllum, Michx, Stem stout ; floral leaves ovate and lance- 

 olate, thick, crowded, sharply serrate, the lowest pinuatirid ; fruit obscurely rough- 

 ened. — Lakes and rivers, from N. New York westward and southward. 



4. M. SCabratum, Michx. Stem rather slender ; lower leaves pinnately 

 parted with few capillary divisions ; floral leaves linear (rarely scattered), pectinate- 

 toothed or cut-serrate : carpels strongly 2-ridged and roughened on the back. — Shallow 

 ponds, from S. New England and Ohio southward. 



* * * Stamens 4 : petals rather persistent : carpels even on the back : leaves chiefly 



scattered, or wanting on the flowering stems. 



5. M. ambiguum, Nutt. Immersed leaves pinnately parted into about 10 

 very delicate capillary divisions ; the emerging ones pectinate, or the upper floral 

 linear and sparingly toothed or entire; flowers mostly perfect; fruit (minute) 

 smooth. — Var. 1. nAtans: stems floating, prolonged. Var. 2. capiliAceum: 

 stems floating, long and very slender ; leaves all immersed and capillary. Var. 

 3. LiMdsuiu : small, rooting in the mud ; leaves all linear, incised, toothed, or 

 entire. — Ponds and ditches, Massachusetts to New Jersey, Pennsylvania, and 

 southward, near the coast. 



6. M. tenellum, Bigelow. Flowering stems nearly leafless and scape-like, 

 (3'- 10' high), erect, simple; the sterile shoots creeping and tufted; bracts 

 small, entire ; floweis alternate, monoecious; fruit smooth. — Borders of ponds, N. 

 New York, New England, and northward. 



2. PROSEEPINACA, L. Mermaid-weed. 



Flowers perfect. Calyx-tube 3-sided, the limb 3-parted. Petals none. Sta- 

 mens 3. Stigmas 3, cylindrical. Fruit bony, 3-angled, 3-celled, 3-seeded, nut- 

 like. — Low, perennial herbs, with the stems creeping at the base (whence the 

 name, from proserpo, to creep), alternate leaves, and small flowers sessile in the 

 axils, solitary or 3-4 together, in summer. 



• 1 . P. palustris, L. Leaves lanceolate, sharply serrate, the lower pectinate 

 when under water ; fruit sharply angled. — Wet swamps : not rare. 



2. P. pectinacea, Lam. Leaves cdl pectinate, the divisions linear-awl- 

 shaped ; fruit rather obtusely angled. — Sandy swamps, near the coast. 



9. HIPPURIS, L. Mare's Tail. 



Flowers perfect or polygamous. Calyx entire. Petals none. Stamen one, 

 inserted on the edge of the calyx. Style single, thread-shaped, stigmatic down 

 one side, received in the groove between the lobes of the large anther. Fruit 



b\- 



