32 SPARGANIACEAE (bUR-REED FAMILY) 



ear: pollen grains simple. — Reported from Denver; abundant on the Atlantic 

 coast; also in Europe and Asia. 



11. SPARGANIACEAE Agardh. Bur-reed Family 



Rootstocks creeping and stploniferous: roots fibrous. Stems simple or 

 branching, sheathed below by the base of the linear leaves. Flowers collected 

 in separate dense and spherical leafy-bracted heads, which are scattered along 

 the summit of the stem; the upper sterile, consisting merely of stamens, with 

 minute scales irregularly interposed; the lower or fertile larger, consisting of 

 numerous sessile 1-2-celled pistils, each surrounded by 3-6 scales much like a 

 calyx. Fruit wedge-shaped or elub-shaped, more or less corky toward the 

 summit, the hard endocarp perforated at the apex. 



SPARGANIUM L. 



Characters of the family. 



Fruits sessile, angvilar . . , 1. SL ennrcaipum. 



Fruits stalked, terete or fusifoim. 

 Emergent and erect. 



Inflorescence branched . • • • • • • » S, 8, androcladum. 



Inflorescence simple • • • • • . . •S.S. simplex. 



Submersed or floating. 



Inflorescence branched . . , , • , , .4.8. angustifolium. 



Inflorescence simple , , 5. S. minimum. 



1. Sparganium eurycarpum Engelm. Gray, Man. Ed. 2. 430. 1866. Stems 

 stout, erect, 5-10 dm. high, with branched inflorescence: leaves mostly flat and 

 merely keeled: pistil attenuate into a short style bearing 2 elongated stigmas: 

 fruit heads 2-6 or more, 2-3 cm. broad: fruit many-angled, sessile, when 

 mature with a broad and depressed or retuse summit, abruptly tipped in the 

 center. — Borders of ponds and streams; across the northern part of wie United 

 States. 



2. Sparganium androcladum (Engelm.) Morong, Billl. Torr. Bot. Club 

 15: 78. 1888. Stems erect, slender, 3-5 dm. high, sparingly or freely branched: 

 pistillate heads 3-7, sessile or the lowest peduncled; style and stigmas 6 mm. 

 long: fruiting heads 12-25 mm. in diameter: fruits fusiform, 5-6 mm. long, 

 smooth or angled at the summit, often contracted- in the middle; the stipe 3 

 mm. long. — In bogs and shallow water; northeastern part of our range to 

 New England. 



3. Sparganium sunplex Huds. Fl. Angl. Ed. 2. 401. 1788. Stems slender, 

 erect, 2-4 dm. high: leaves more or less triquetrous: fertile heads (1-4) of the 

 usually simple inflorescence often above the axils, sessile or peduncled, 12- 

 15 mm. wide in fruit: stigma linear, equaling the rather slender style, or 

 shorter: nutlets pale, fusiform or narrowly oblong, about 4 mm. long, more or 

 less contracted in the middle. — Northern Wyoming and thence across the 

 continent. 



4. Sparganiiun angustifolium Michx. Fl. Bor. Am. 2: 189. 1803. Floating 

 in shallow or deep water: stems slender: leaves long and narrow, flat with 

 sheaths often inflated at base: inflorescence 3-10 cm. long: staminate heads 

 1-4; pistillate 1-4, usually above the axil, sessile or the lower pedicpled: 

 mature fruiting heads 7-15 mm. in diameter; nutlets often contracted in the 

 middle. — Seemingly frequent in our range; from New Poundland to California. 



5. Sparganium minimum Fries. SummaVeg.Skand. 2: 560. 1846. .Usually 

 floating, with very slender stems and thin flat narrow leaves: fertile heads 1 or 

 2, axillary, sessile or peduncled, 8-10 mm. wide; stigma oval, about as long as 

 the short style, scarcely surpassing the oval or obovate denticulate scales: 

 fruit oblong-obovate, 2-4 mm. long, pointed, somewhat triangular, the stipe 

 very short. — Colorado to New England. 



