242 HALORAGEiE. Myriophyllbm. 



pinnately cut into numerous fine segments. Flowers sessile in the axils of the upper leaves ; 

 sometimes in terminal spikes, from the leaves being reduced to bracts ; the uppermost 

 commonly staminate (with abortive pistils), the lowest fertile (with abortive stamens), and 

 the intermediate ones perfect. 



§ 1. Fl<fwers octandrous : carpels not ridged on the back: leaves veriicillate. 



1. Myriophyllum spicatum, Linn. Spilced Water Milfoil. 



Leaves all pinnately cut into capillary segments ; bracts shorter than the flowers, ovate, 

 entire, the lowermost larger and serrate ; petals broadly ovate ; carpels smooth and even. — 

 Linn. sp. 2. p. 992 ; Michx. /. 1. p. 190 ; Engl. hot. t. 83 ; Pursh, fi.l. p. 274 ; Ell. sk. 

 2. p. 588 ; Torr. comp. p. 354 ; Bigel. fi. Bost. p. 345 ; DC. prodr. 3. p. 68; Hook. fi. 

 Bor.-Am. 1. p. 216 ; Torr. ^ Gr. fl. N. Am. 1 . p. 529. 



Stem varyuig in length with the depth of the water, sometimes 10 - 15 feet long, slender. 

 Leaves 3 - 5 in a whorl, all very finely cut. Flowers in an interrupted leafless spike, which 

 rises above *he wat" ; the upper bracts or floral leaves entire, very small, but increasing in 

 length towards the lower part of the spike, where they are sharply serrate. 



Deep ponds and slowly flowing waters ; not common. July - August. 



2. Myriophyllum verticillatum, Linn. Whorled Water Milfoil. 



Lower leaves cut into capillary segments ; floral ones, or bracts, pectinately pinnatifid, 

 commonly much longer than the flowers ; petals oblong-obovate ; carpels smooth and even. — 

 Linn. sp. 2. p. 992 ; Michx. fl. 2. p. 190 ; Engl. hot. t. 218 ; Pursh, fl. 1. p. 274 ; Ell. sk. 

 2. p. 588 ; Torr. compend. p. 355 ; DC. prodr. 3. p. 68 ; Torr. ^ Gr.fl. N. Am. I. p. 529. 



Stem very long, stouter than in the preceding species. Submerged leaves all finely divided ; 

 those belonging to the cmersed part of the stem, much smaller and pectinate. Flowers in a 

 leafy spike. Segments of the calyx much smaller than the petals, acute. Anthers oblong. 

 Stigmas large and ihick ; the surface covered with purplish woolly hairs. 



Ponds and small streams ; rather conimon. July - September. 



^ 2. Flowers tetrandrous : carpels with one or two ridges on the hack : leaves vcrticillate. 



3. Myriophyllum heterophyllum, Michx. Various-leaved Water Milfoil. 



Stem thick ; lower leaves cut into capillary segments ; floral ones ovate or lanceolate, thick, 

 sharply serrate, crowded, usually 5 in a whorl ; petals oblong ; carpels minutely roughened, 

 slightly 2-ridged and tuberculate on the back. — Michx. fl. 2. p. 191 ; Pursh, fl. 1. p. 274 ; 

 Ell. sk. 2. p. 588 ; Torr. comp. p. 355 ; DC. prodr. 3. p. 69 ; Torr. ^ Gr. fl. N. Am. 1. 

 p. 529. 



Stem very long ; much stouter, and the submerged leaves smaller, than in the preceding 



