32 Rhodora [FEBRUARY 
E. Leaves soft and mostly translucent, flat or ob- 
scurely keeled: bracts spreading or spreading- 
ascending: inflorescence simple or branched, the 
branches (when present) usually with 1-3 pistil- 
late and 1-6 staminate heads: stigma 1-2 mm. 
long: fruiting heads 1.5-2.5 cm. in diameter: ma- 
ture carpels opaque or but slightly lustrous; stipe 
2-3 mm. long; body 4.5-5.5 mm. long, about 2 
mm. thick; beak 1.5-5 mm. long: receptacle 
scarcely alveolate: anthers 0.8-1.2 mm. long... 3. S. americanum, 
D. Some of the heads or branches supra-axillary. F. 
F. Commonly erect and emersed: leaves flat or 
slightly keeled, little if at all dilated at base (ex- 
cept for the scarious margin): staminate half of 
inflorescence 2-10 cm. long, of 4-9 scattered 
heads (if shorter and with fewer heads, the plant 
very low and with ribbon-like translucent erect 
lower bracts): beak of fruit 2-4.3 mm. long: 
sepals appressed, cuneate-spatulate, scarcely 
narrowed id GSEEW...... 6405 can ke 4. S. chlorocarpum. 
F. Commonly submersed or floating, sometimes 
emersed: leaves rounded on the back; the middle 
and upper with dilated and subinflated sheath- 
ing bases: staminate half of inflorescence 1-3 cm. 
long, of 1-4 (rarely -6) crowded heads: beak 
about 2 mm. long: sepals loosely ascending, with 
slender claw and dilated tip................ 5. S. angustifolium. 
C. Sepals borne chiefly along the middle of the stipe, 
rarely reaching the middle of the fruit: epicarp closely 
investing the seed: fruit with a strong gladiate-faleate 
beak: stigma oblong to lance-ovate, 0.4-0.7 mm. long: 
anthers 0.4-0.7 mm. long: plant aquatic, with flat 
translucent loosely cellular-reticulate leaves and 
branching inflorescences........,...:00e0wscwwney 6. S. fluctuans. 
B. Staminate head 1: fruiting heads 5-12 mm. in diameter: 
mature carpels ellipsoid- or slenderly obovoid-fusiform, 
3-5.5 mm. long; stipe obsolete or up to 1 mm. long; beak 
obsolete or up to 1.5 mm. long: inflorescence simple. G. 
G. Pistillate heads all axillary: fruit tapering to a conical 
beak 0.5-1.5 mm. long: sepals elliptic to cuneate- 
spatulate, 144-24 as long as the body of the fruit...... 7. S. minimum. 
G. One or more of the heads supra-axillary : fruit beakless: 
sepals wanting or slenderly spatulate and rarely L4as 
long as the body of the fruit..................... 8. S. hyperboreum. 
1. S. EURYCARPUM Engelm.—Shallow water at i of ponds, 
pools and streams, chiefly at low altitudes, widely dispersed over the 
United States and southern Canada, northward with us to the Great 
Lakes and St. Lawrence (east to Rimouski Co., QuEBEC), Champlain 
Valley, Vermont, Franklin, southern Penobscot and Washington 
Cos., MAINE, southern and southeastern New BnuNswiIck, central 
and eastern Nova Scotia, Prince Epwarp IsrAND and the MAGDA- 
LEN ISLANDs. 
2. S. ANDROCLADUM (Engelm.) Morong. S. lucidum Fernald & 
Eames.—Muddy or peaty shores, swamps or shallow water, eastern 
