96 SELECTED WESTERN FLORA 



4. CIRCEA. Enchanter's Nightshade. 



Calyx tube hairy, slightly prolonged, deciduous, 2-lobed, the lobes 

 reflexed; petals 2, obcordate; stamens 2, alternate with the petals; 

 fruit 1-2-oelled, small, densely covered with hooked hairs. Low 

 perennial herbs with opposite leaves and small white flowers in 

 terminal or axillary racemes. 



1. C. alpina, L. 



Slender, 3-8 in. high; leaves ovate, slender petioled, more or less cordate, 

 strongly dentate; flowers small, white; fruit covered with weak hooks. 

 Moist woods. Rocky Mts., northward and eastward. 



LX. HALORAGIDACE-ffi (Watee Milfoil Family). 



Aquatic or marsh plants with inconspicuous sessile flowers in the 

 axils of the leaves. Calyx tube adhering to the ovary, the teeth 

 minute or wanting; petals small or none; stamens 1-8; fruit 1-4- 

 ceUed, indehiscent. 



1. MYRIOPHfLLUM. Water Milfoil. 



Flowers monoecious or perfect; calyx 4-parted or toothed; petals 

 4 or none; stamens 4-8 ; fruit 47-lobed and 4^celled. Perennial water 

 herbs with the leaves often in whorls, and the submerged ones cut 

 into capillary divisions; flowers in the axils of the upper leaves, 

 usually above the water. 



1. M. spicatum, L. 



Leaves somewhat rigid, not entirely collapsing when removed from the 

 water ; staminate flowers purplish, in cluster?, more or less whorled on the 

 upper part of the stem. Slow streams, Man.— Alta. 



2. M. verticellatum, L.; var. pectinatum, Wallr. 



Much resembling the preceding, but the leaves entirely collapsing when 

 withdrawn from the water ; staminate flowers pale green or pinkish, and the 

 fruit of four distinct carpels. Ponds, local. Marshes of Porcupine Mts. 

 (Macoun.) 



2. HIPPURIS. Mare's-tail. 



Flowers perfect, calyx entire; petals none; stamen 1, on the 

 calyx; style thread-like and stigmatie down one side ; fruit 1-ceUed 

 and 1-seeded. Aquatic herbs with simple erect stems and linear 

 leaves arranged in whorls. 



