Aquatic and Wetland Vascular Plants of the Northern Great Plains
64. Sparganiaceae, the Burreed Family
1. Sparganium L. -- Burreed
3. Sparganium eurycarpum Engelm. -- Giant burreed
Rather robust, typically emergent plants 4-10 dm tall. Leaves bright
green, 4-11 mm wide, spongy toward the base, sharply keeled on the back, the
margins scarious toward the base. Inflorescence 1-3 dm long, sparsely
branched from the axils of foliaceous bracts, the branches simple, loosely spicate;
staminate heads numerous, 1-2 cm in diameter at anthesis; anthers
linear, 1-1.8 mm long; pistillate heads 1-4(8), 1.5-2.5 cm in diameter
in fruit; stigmas 2, linear, 2-4 mm long. Achenes sessile to short-stipitate,
brown on the summit, golden-brown on the sides, obconic to obpyramidal, angled
on the sides, the body 6-8 mm long, 4-7 mm wide at the summit, the beak (excluding
the stigmas) 1-4 mm long, the persistent perianth of 4-8 scales appressed to
the achene, the scales about equaling the achene body. Mid Jun--Aug. Usually
in shallow water of marshes, streams, ditches, ponds and lakes, often occurring
with cattails; common, often abundant; (Newf. to B.C., s to NJ, OH, IN, MO,
OK, AZ and CA).
Sparganium eurycarpum: a) in flower. b) enlargement of fruit cluster.