466 MINNESOTA BOTANICAL STUDIES. 
erect to creeping and rooting at the nodes; aquatic or in low 
Veto TOMNG. fOr) termesthial sac. sescieoams cnensneee ens Sec. FLAMMULA. 
C. Blades of stem leaves amplexicaul, leaves entire; flowers 
WW IMIG: SNe ME As St oe. sanece etnies bo masrencecs 75. amplextcaults. 
CC. Blades of stem leaves not amplexicaul; flowers yellow. 
D. Stamens numerous. 
E. Plant low or erect, not spreading by slender creeping 
stems. 
Hie pdinaitalb tag iatic:: >< .tonnce- seeemenencee 76. Lambertianus. 
FF. Habitat terrestrial. 
G. Sepals and petals persistent........... 77. arnoglossus. 
GG. Sepals and petals deciduous. 
H: Claw of petal 1 dine long...-...- 78. ungutculatus. 
HH. Claw of petal not nearly so long. 
I. Akenes beaked. 
J. Stems 2 to 3 feet high, often rooting at lower 
MOGES Wak, eh otk BAER ls oreuie pas 79. ambigens. 
JJ. Stems much lower, not rooting at nodes. 
K. Mature fruit glabrous. 
L. Beak as long as the akene body. 
So. Madrensis. 
LL. Beak much shorter than akene body. 
M. Petals 4 to 6 lines long; plants soli- 
tary, not much tufted..$1. alisme@efolzus. 
MM. Petals about 3 lines long; plants 
often tufted or covering the ground. 
82. altsmellus. 
KK. Mature fruit villous-pubescent. 
83. Lemmont. 
II. Akenes beakless; styles deciduous. 
84. oblongifolius. 
EE. Plant spreading by slender, or fistulous creeping stems. 
F. Lower leaves sometimes cordate; flower stems ascend- 
ing. 
G. Margins of some of the leaves slightly denticulate. 
85. hydrocharotdes. 
GG. Margins of leaves entire............. 86. samolifolius. 
FF. Lower leaves never cordate. 
G. Petals no longer than the sepals....... 87. stolontfer. 
GG. Petals nearly twice the length of the sepals. 
H. Number of petals 8 to 10; plant glabrous. 
88. vagans. 
HH. Number of petals 4 to 8; plants never entirely 
glabrous. 
