, 4 POTAMOGETONACEAE. 



., Bower ile; fruit broadly obovoid. S. eurycarpum. 



Fertile flowers stalked; fruit fusiferm. 



Heads all axillary; inflorescence branched. S. androcladum. 



I!, ads, or a1 least some of them, supra-axillary. 



or at least the larger ones, keeled; usually 



' terrestrial 5 - «»»#«*• 



I ,. a r- m.t keeled; floating aquatics. , . 



Be lb of fruit short-conical; stigma oblong. 6. minimum. 



Beak of fruit slender; stigma linear. S. angushfohum. 



Sparganium eurycarpum Engelm. Stems stout, erect, 100-150 cm. high; 



,,- flat, slightly keeled; staminate heads several to many; pistillate heads 

 peduncled, 15-30 mm. in diameter; fruit obtusely 4 or 5 angled, 

 in. long, abruptly tipped in the center. Common in marshes and on 

 Like margins. 



Sparganium androcladum (Engelm.) Morong. Stems stout, 40-100 cm. 

 high; |i i 1 mm. wide, dark green; inflorescence branched, the branches 



Strictly axillary, each bearing 3-7 staminate heads and usually 1 or 2 pistillate 

 heads; fruiting heads 2-2.5 cm. in diameter; fruits dull, the fusiform body 

 5-6 mm. long, the beak about 3 mm. long. Mouth of St. Joe River, Idaho. 



Sparganium simplex Huds. Stems rather stout, 30-60 cm. high; leaves 



thin. 6-15 mm. broad, scarious-margined below; inflorescence simple; fruiting 



\1 25 mm. in diameter, some of them supra-axillary; fruit fusiform, 



somewhat shiny, the body 3-4 mm. long, tipped with a beak about as long; 



stalk 1 2 mm. long; stigmas linear. In bogs or pond margins. 



Two forms occur in our limits, one having heads about 2 cm. in diameter 

 with very shiny fruits whose conical body is shorter than the beak; the other 

 with smaller heads, 15 mm. in diameter, and the fruits rather dull, with the 

 body abruptly tipped with a shorter beak. Perhaps neither plant is true 

 S. simplex. 



Sparganium minimum Fries. Aquatic; stems very slender, 10-40 cm. long; 



ives thin and grass-like. 2-4 mm. broad, floating; inflorescence simple; 



ids sessile or nearly so, the pistillate about 1 cm. in diameter when mature; 



nutlets smooth, ovoid, conically short-beaked, easily detached. In the lakes 



i ne County and northern Idaho. 



Sparganium angustifolium Michx. Aquatic; stems slender, 30-100 cm. 



very long and narrow, rather firm, 2-4 mm. wide; inflorescence 



simple; beads sessile or the lower peduncled, the pistillate 15-20 mm. in di- 



r when mature; nutlets abruptly slender-beaked, firmly attached. In 



the Like- of northern Idaho. 



Family 11. POTAMOGETONACEAE. 



I lerbs, Bubmersed or floating in fresh or salt water; with mostly 



J-ranked l< - mostly small, solitary or in spikes, 



\u.il or perfed , regular; perianth none or rarely sheath-like; 



tamena 1 4; carpels 1-4, each 1-ovuled; fruits drupaceous or 



membranaceous. 



n ?P ike *; 24. POTAMOGETON, 15. 



ial, m axillary clusters. 25. Zannichellia, 16. 



