40 I<L0l<A. 



heads 3-7, sessile or the lowest peduncled, axillary or the peduncles and branches 

 axillary; style 1 ; stigma I (rarely 2); fruiting heads 12-25 mm. in diameter; nut- 

 lets fusiform, 4 nun. long, ; mm. thick, often Strongly contracted at the middle, 

 tapering into the style ; scales oblong, as long as the nutlets or shorter, the exterior 

 ones narrower ; stalk of fruit 2 mm. long or more. In bogs or shallow water, N. S. 

 to Out. and Br. Col., south to Ida. and La. June-Aug. 



Sparganium androcladum fliictuans Morong. Floating in deep water with long 

 slender stiins and thin leaves a— 7 nun. wide; inflorescence usually sparingly branched ; 

 fruiting heads &-ia nun. in diameter. In cold ponds, N. B. to Penn. 



3. Sparganium simplex Iluds. Simple-stemmed Bur-reed. (I. F. f. 140.) 

 Stem slender, 3-60 cm. high, simple. Leaves more or less triquetrous, 4-8 mm. 

 wide; Inflorescence 2-20 cm. long; staminate heads 4-6; pistillate 2-6, sessile or 

 the lowest peduncled ; fruiting heads 10-16 mm. in diameter ; nutlets fusiform or 

 narrowly oblong, obtusely angled at the apex, more or less contracted in the middle, 

 smaller than those of the preceding species and more tapering at the summit ; scales 

 denticulate, about one-half as long as the nutlets ; stigma linear, as long as the style or 

 shorter, rarely 2 ; stalk of fruit about 2 mm. long. Borders of ponds and streams, 

 IS'ewf. to 1 Jr. Col., Penn., Mont, and Cal. June-Aug. 



Sparganium simplex angustif61ium (Michx.) Engelm. Floating in deep water. 

 Leaves very long, 1-3 mm. wide, their sheaths often inflated at the base; staminate and 

 pistillate heads 1-4 ; fruiting heads 6-15 mm. in diameter. In mountain lakes and slow 

 streams, Newf. to Ore., N. Y. and Cal. 



4. Sparganium minimum Fries. Small Bur-reed. (I. F. f. 141.) Float- 

 ing, stems very slender, o. I-I m. long. Leaves thin and lax, 1-5 mm. wide ; inflor- 

 escence 2 cm. or more long ; staminate heads 1-2 ; pistillate, 1-3, sessile, axillary, 

 supra-axillary or the lowest on an axillary peduncle ; ripe fruiting heads 4-10 mm. 

 in diameter; nutlets ovoid, slightly triangular, tapering abruptly into the style, 

 2-4 mm. long, twice as long as the denticulate scales ; stigma ov?l, often oblique, 

 about as long as the style; stalk of the nutlet 0.5-1 mm. long, often apparently 

 none. In ponds and streams, N. B. to Man. and Ore., south to -N. J., Mich, and 

 Utah. Also in northern Europe. Dwarf forms, growing out of water, sometimes 

 occur with stems 3'-6' high. June-Aug. 



Order 2. NAIADALES. 



Aquatic or marsh herbs, the leaves various in form. Flowers perfect, 

 monoecious or dioecious. Perianth present, or wanting. Parts of the 

 flower mostly unequal in number. Carpels i or more, mostly distinct and 

 separate (united in Vallisneriaceae ; united at least until maturity in 

 Sihcuchzeriaceae) ; endosperm none, or very little. 



Perianth, if present, inferior; carpels mostly distinct. 

 Perianth-segments, when present, herbaceous. 



Carpels distinct; aquatic herbs. Fam. i. Naiadaceae. 



Carpels united until maturity; bog- plants; flowers racemed or spiked. 



Fam. 2. Scheuchzeriaceae\ 

 Perianth of 2 series of segments, the outer green, the inner mostly white. 



Fam. 3. Alist/utceae. 

 Perianth superior; carpels united. Fam. 4. Vallisneriaceae. 



Family 1. NAIADACEAE Lindl.* 



Immersed aquatic plants with slender, often branching, leafy stems, the 

 leaves flat or filiform, and perfect, monoecious or dioecious, spicate axil- 



Contributed by the late Rev. Thomas Morong. 





