HALORAGIDACEAE (WATER MILFOIL FAMILY) 345 



stems usually simple, 1.5-3 dm. high, from a small tuber: leaves ovate, 

 rounded or cordate at base, acute or acuminate, repandly denticulate, 3-7 cm. 

 long; the slender petiole about as long: racemes without bracts: calyx white, 

 with a very short tube: fruit rather loosely covered with soft hairs, 1-celled, 

 1-seeded. In close damp woods; Wyoming to California and Washington. 



2. Circaea alpina L. Sp. PL 9. 1753. Glabrous, stems weak, 1-2 dm. high, 

 often branching above: leaves cordate, shining, rather coarsely toothed, 

 2-4 cm. long, on slender petioles nearly as long as the blade: pedicels sub- 

 tended by minute setaceous bracts; flowers reddish, especially before open- 

 ing: fruit pubescent but scarcely hispid. Colorado to Northeastern America. 



82. HALORAGIDACEAE Kl. & Garcke. WATER MILFOIL 



FAMILY 



Perennial aquatic herbs, with alternate or verticillate leaves, which if im- 

 mersed are usually dissected. Flowers inconspicuous, sessile in the axils 

 of the leaves or bracts, perfect, monoecious, or dioecious. Calyx-tube entire 

 or 4-lobed. Corolla small or wanting. Stamens 1-8. Ovary 1-4-celled, ad- 

 nate to the calyx-tube. Fruit indehiscent, nut-like, of 2-4 one-seeded carpels. 



Leaves entire, in whorls of 6-12 1. Hippuris. 



Leaves dissected, in whorls of 3-5 ....... 2. Myriophyllum. 



1. HIPPURIS L. MARE'S-TAIL. BOTTLE BRUSH 



Smooth erect herbs from running rootstocks, growing in shallow ponds and 

 on muddy banks. Leaves simple, entire, linear, in whorls of 8-12. Flowers 

 solitary, perfect. Calyx-tube entire. Petals wanting. Stamen one. Ovary 

 1-celled, 1-seeded, indehiscent and drupe-like. 



1. Hippuris vulgaris L. Sp. PI. 4. 1753. Glabrous, slender, 2-5 dm. high: 

 leaves 1-3 cm. long, or the submerged ones often longer: the stamen with a 

 short, thick filament: style filiform, stigmatic throughout. Across the north- 

 ern part of the continent and south in the mountains to New Mexico. 



2. MYRIOPHYLLUM L. WATER MILFOIL 



Smooth, leafy herbs. Leaves whorled in threes or fours. Upper flowers 

 usually staminate, the lower pistillate, and the intermediate ones perfect. 

 Limb of the calyx 4-lobed in the sterile flowers, wanting or minutely toothed 

 in the others. Petals 2-4, minute or wanting in the pistillate flowers. Sta- 

 mens 8 (in ours). Ovary 4-celled; stigmas recurved and plumose. 



Floral leaves (bracts) shorter than the flowers 1. M. spicatum. 



Floral leaves (bracts) longer than the flowers 2. M. verticillatum. 



1. Myriophyllum spicatum L. Sp. PL 992. 1753. Leaves in whorls of 4-5, 

 all pinnately parted into capillary divisions, except the floral ones or bracts; 

 these ovate, entire or toothed and mostly shorter than the flowers, which 

 thus form an interrupted spike: petals deciduous: stamens 8: carpels rounded 

 on the back, with a deep groove between them. Common in our range, and 

 across the continent; also in the Old World. 



2. Myriophyllum verticillatum L. 1. c. Very similar but the whorls mostly 

 of 3-4 leaves; the floral also pinnately parted into linear segments and very 

 many times longer than the flowers: petals of the staminate flowers 4, pur- 

 plish: otherwise much like the preceding. Rare in our range; across the 

 continent; also in Europe and Asia. 



