Family 2. SPARGANIACEAE 
By PER AXEL RYDBERG 
Perennial monoecious, marsh or water plants, with horizontal rootstocks and 
with fascicles of fibrous roots at the base of the stem. Stems erect, or im- 
mersed and floating. Leaves linear, alternate, flat or more or less triangular- 
keeled below, sheathing at the base. Flowers in dense globose heads on the 
upper part of the stem or its branches, sessile or peduncled, the staminate ones 
uppermost. Perianth of several (3-6) chaffy scales. Stamens mostly 5; fila- 
ments distinct ; anthers oblong. Pistils 1, or 2 with ovaries and styles united ; 
stigmas oblong, lanceolete, or linear; ovules anatropous. Fruit 1- or 2-celled, 
nut-like, each cell with a single seed. Endosperm copious, surrounding the 
straight embryo. 
1. SPARGANIUM L. Sp. Pl. 971. 1753. 
Characters of the family. 
Type species, Sparganium erectum L. 
A. Achenes broadly obovoid or cuneate-obpyramidal, sessile, distinctly 
beaked; inflorescence compound; fruiting heads 2-3 cm. in 
diameter ; leaves’somewhat keeled. 
Achenes cuneate-obpyramidal, almost as broad as long, truncate or 
depressed at the summit. 1, S. eurycarpum, 
Achenes obovoid, decidedly longer than broad, rounded at the 
summit. 
Fruiting heads 2-2.5 cm. in diameter ; body of the achenes 7-9mm. 
long ; claws of the sepals narrow. 2. S. Greenet. 
Fruiting heads 2.5-3 cm. in diameter; body of the achenes fully 1 
cm. long; claws of the sepals dilated below the middle, almost 
as broad as the blades. 3. S. californicum. 
B. Achenes fusiform (in S. minimum somewhat obovoid, but then 
short-beaked and short-stipitate). 
a. Stipes and beaks each 2 mm. long or more ; fruiting heads 1.5 cm. 
in diameter or more; anthers 3-4 times as long as broad. 
* Beaks straight or slightly curved ; stigmas linear. 
Heads all axillary; beaks shorter than the bodies of the 
achenes ; leaves more or less keeled. 
Achenes dull ; stigmas 2 mm. long or less. 
Inflorescence branched ; branches geniculate, bearing 
3-7 staminate heads. 4. S. androcladum. 
Inflorescence simple, or, if branched, the branches 
strict and bearing 0-2 staminate heads, 5. S. americanum. 
Achenes glossy ; stigmas 2.5-3.5 mm. long. 6. S. lucidum, 
Heads, at least some of them, supra-axillary. « 
Leaves, at least the middle ones, strongly triangular- 
keeled ; stem usually erect, strict. 
Fruiting heads more than 2 cm. in diameter; bracts 
ascending-spreading ; beaks fully as long as the 
bodies of the achenes. 
Leaves 7-15 mm. wide, strongly veined ; fruiting heads 
about 3 cm. in diameter ; achenes brown, shining, 
gradually tapering into the beaks. 
Leaves 3-8 mm. wide, weakly veined ; fruiting heads 
2-2.5 cm. in diameter ; achenes green, dull, abruptly 
contracted into the beaks. 8. S. chlorocarpum. 
Fruiting heads rarely 2 cm. in diameter; stem slender; 
leaves narrow ; bracts almost erect. 
Heads distant, nearly 2 cm. in diameter; achenes 
s! 
. SL simplex. 
grayish-brown, distinctly nerved. : 9. S. diversifolium. 
Heads approximate, about 1.5 cm. in diameter; 
achenes dark olive-brown, not nerved. 10. S. acaule. 
Leaves not keeled or only slightly so, narrow and slender ; 
stem weak and often floating ; beaks decidedly shorter than 
the bodies of the achenes. 
VoLUME 17, Part 1, 1909] 5 
