fruit urceolate, with rounded or obtuse angles, 3-4 mm. long, 2-3 mm. broad. 



In peaty soils of swamps and savannahs and in shallow water, rare in s.e. Tex., 

 spring-summer; mostly in the Coastal Plain from N.S. and s.w. Me., s. to Tenn., 

 Fla. and Tex. 



2. Myriophyllum L. Water-milfoil 



Perennial aquatics; stems mostly elongated; leaves usually whorled (in ours), 

 the submersed ones pinnately parted into capillary divisions; flowers unisexual and 

 perfect on the same plant, small, sessile, chiefly in the axils of the upper leaves or 

 bracts, usually above water in summer, the uppermost ones staminate; calyx of the 

 staminate flowers 4-parted, of the pistillate flowers 4-toothed; petals 4 or none; 

 stamens 4 or 8; stigmas 4, recurved; fruit nutlike, 4-celled, deeply 4-lobed. 



About 45 species, cosmopolitan. 



Wildfowl, especially ducks, are known to eat the fruits of these species, and they, 

 as well as muskrats, occasionally eat the herbage. Several species, especially M. 

 heterophylhim, M. brasiliense and M. exalbescens, frequently become a weedy nui- 

 sance. All of the plants form shelter and provide a breeding place for fish and 

 insects; the latter, in turn, provide food for fish and water birds. The lower stems 

 and roots are said to provide a nesting place for black bass. 



1. Leaf whorls on middle and lower parts of stem mostly 1 cm. or more apart 

 (2) 



1. Leaf whorls on middle and lower parts of stem usually much less than 1 cm. 



apart (4) 



2(1). Leaf divisions stoutish, mostly less than 6 mm. long; flowers borne in 

 clusters in the axils of leaves 1. M. brasiliense. 



2. Leaf divisions filiform, typically 6 mm. or more long; flowers borne in whorls 



on a slender terminal spike, mostly longer than the subtending 

 bract (3) 



3(2). Lowermost bracteal leaves commonly exceeding the flowers and fruits, 

 pectinate to serrate; leaves of middle whorls usually less than 2.5 

 cm. long, with 12 or more segments on each side of rachis, the 

 segments rarely to 1.5 cm. long; stems reddish-brown to pinkish- 

 tawny in drying 2. M. spicatum. 



3. Lowermost bracteal leaves not exceeding the flowers and fruits, serrulate to 



entire; leaves of middle whorls usually 3 cm. long or more, with 

 1 1 or fewer segments on each side of rachis, the segments com- 

 monly more than 1.5 cm. long; stems whitish in drying 



3. M. exalbescens. 



4(1). Floral bracts pinnately dissected or lobed 4. M. verticillatum. 



4. Floral bracts entire or only toothed (5) 



5(4). Leaves mostly all in definite whorls; submersed leaves with 5 to 10 capil- 

 lary divisions on each side; bracteoles ovate to lanceolate, acuminate; 

 carpels with 2 smoothish dorsal ridges 5. M. heterophylhim. 



5. Leaves whorled, subverticillate, opposite or alternate on the same plant; sub- 



merged leaves with about 5 capillary divisions on each side; brac- 

 teoles obtusely triangular; carpels with 2 prominently tuberculate 

 dorsal ridges 6. M. pinnatiim. 



1. Myriophyllum brasiliense Camb. Parrot's-feather, water-feather. Fig. 566. 



Plants pallid or light-green, with the upper part emersed or trailing on mud or 

 seepage and erect-ascending: stems simple or sparsely branched; leaves all whorled, 

 oblong in outline, stifiish, 2-5 cm. long, puberulent when young, glabrous with age, 

 dissected into 10 or more pectinately arranged linear-filiform divisions on each side, 

 the upper divisions 3-6 mm. long, the lower divisions much-reduced; bracteoles 



1202 



