6 
@Q Amphibious plants of wet muddy shores; leaves mostly 15-24 cm. long, 
(the blades) / slender, soft,\linear from an abruptly narrowed membranaceous 
« 
a \. base l. I. Howellii 
OD Immersed aquatics in 0,5-6 feet of water; leaves mostly less than 
15 cm. long, firm to rigid, gradually tapering from a wide 
4 t ciciestene. base 
DP Stomata usually few; sporangia oblong; megaspores white, spinose; 
i microspores usually smooth; leaves often spreading 2e le Braunii 
‘ 2 Stomata wanting; sporangia suborbicular; megaspores cream-colored, 
é with low prominent crests, forming a network on basal 
i face; microspores spinulose; leaves chiefly ascending 
Se le occidentalis 
1, I. Howellii Engelm, Slender plants, the leaves 10-30, long acicular, 
slender, bright green, often abruptly narrowing from a wide membranaceous 
qi) base, or again tapering for 1-5 cm, above(sporangium level, the stomata Ghdy 
numerous; ligule narrow, elongated-triangular; sporangia orbicular to oblong, 
3-6 (or 8) mm, long, often brown-spotted, as much as 1/3 covered by velum; 
megaspores white, variously finely tuberculate, microspores chiefly smoothish, 
Amphibious in wet ground about ponds, on stream and lake shores, our 
most common Isoetes at middle elevations, the spores maturing in adjacent 
mud when the plants are growing in standing watere Paradise Cr, near Moscow; 
forks St, Maries Re; Lake Coeur d'Alene; Lake Pend Oreille; Sandpoint, 
I, Bolanderi Engelm. A closely related species, of submersed habit, the 
stomata few, sporangia 3-4 mm, long, 1/4-1/3 covered by velum, megaspores 
obscurely tuberculate, the microspores more or less spinulose, To be 
expected in the southern part of our region; Bear Cr., Bitter Root For, Res., 
Leiberg 2939. 
