GENUS 3. 



WATER MILFOIL FAMILY. 



615 



3. Myriophyllum alterniflorum DC. Loose-flowered Water-Milfoil. Fig. 3083. 



Myriophyllum alterniflorum DC. Fl. Franc. Suppl. 529. 1815. 



Submerged leaves usually in whorls of 3-5, occasionally 

 scattered, the pinnate divisions capillary, 3"~5" long. 

 Spikes short, i'-2 long, numerous or several on the 

 branching stems; uppermost floral leaves ovate or linear, 

 entire or minutely toothed, smaller than the flowers, early 

 deciduous; flowers mostly in pairs or solitary; petals of 

 the staminate flowers 4, longer than the stamens, pale 

 rose-color, deciduous; stamens 8; fruit nearly i" long, 

 slightly less than i" thick; carpels rounded on the back, 

 with a deep groove between them. 



In deep water, Newfoundland to eastern Massachusetts and 

 Ontario. Greenland. Common in Europe. 



4. Myriophyllum tenellum Bigel. Slender Water-Milfoil. Fig. 3084. 



Myriophyllum tenellum Bigel. Fl. Bost. Ed. 2, 346. 1824. 



Stems slender, scape-like, nearly leafless, simple, erect, 

 i2'-6' or 'rarely 12' high. Rhizome creeping, sending up 

 many sterile stems; flowers alternate, solitary; uppermost 

 bracts obovate, often longer than the monoecious flowers, 

 the lower oblong, often shorter, the lowest minute or 

 wanting ; petals 4, purplish, longer than the 4 stamens ; 

 fruit i" long and about as thick at the top, sometimes 

 enlarged at the base ; carpels rounded or obtusely angled 

 on the back, separated by a shallow groove. 



Sandy bottoms of ponds and streams, Newfoundland to New 

 Jersey, Pennsylvania, Ontario and Michigan. 



5. Myriophyllum humile (Raf.) Morong. Low Water-Milfoil. Fig. 3085. 



Burshia humilis Raf. Med. Rep. (II.) 5: 361. 1808. 

 Myriophyllum ambiguum Nutt. Gen. 2: 212. 1818. 

 Myriophyllum humile Morong, Bull. Torr. Club 18 : 242. 1891. 



Typical form terrestrial, i'-ii' high, rooting in mud 

 on shores. Leaves linear, entire or pectinate. Floating 

 forms with stems often 12' long, branched, with all or 

 most of the leaves pectinate into capillary segments; 

 these produce the typical form if they take root; petals 

 4, purplish; stamens 4; fruit usually less than i" long 

 and about as thick at base, its carpels smooth, or rarely 

 slightly roughened, separated by a shallow groove. 



In ponds, Maine to Rhode Island, Maryland and recorded 

 west to Illinois and Tennessee. Variable in appearance, but 

 the variations are manifestly only conditions of the plant dependent upon its environment. 



