276 BOTANICAL GAZETTE [ocTOBER 
light yellowish green, usually with a vitreous or metallic luster: stems 
prostrate when not submerged, ascending or floating when in the 
water, abundantly branched, sometimes sparingly so in water, 
defoliate in the older portions by the maceration of the leaves, 3 to 
8 long, 180 to 210m in diameter, scarcely angled ; central strand 
rudimentary or none, when present of three to six rows of cells; 
cortex of two to four layers of cells 8.6 to 13min diameter, cells 
of ground tissue 13 to 20 in diameter, abruptly larger than the 
cells of the cortex; branches simple, inclined or suberect, 1.5 to 
4™ long in terrestrial forms, longer in submerged plants, 3 to 
7-™, often with tips slightly hooked: leaves ovate, ovate lanceo- 
late or oblong lanceolate, average leaves 650 to 7004 wide 
and 1500 to 1600p long, concave, very slightly or not at aul acu- 
minate, point usually blunt, entire, strongly costate, costa plano- 
convex in the basal fourth of the leaf, double convex to almost 
cylindrical above, one-sixth to one-fourth the leaf base at the 
line of insertion, 85 to 120 in width, tapering somewhat to the 
tip of the leaf, here 45 to 6op in width, flattening and disappear- 
ing abruptly within the point, strictly erect or slightly spreading, 
occasionally subsecund, slightly incurved when dry, especially 
in terrestrial forms, not decurrent; leaf cells parenchymatous in 
lower half, at base /arge, 13 to 21.5 wide by 30 to 704 long, 
averaging across the base r6m wide by gou long; passing gradu- 
ally into cells above varying from linear rectangular to linear 
rhomboidal or shorter, 10.54 wide by 3 to 7# long; these again 
passing gradually into cells regularly hexagonal, 10.54 wide by 
38 long, cells at apex 15 wide by 30 long, alar cells rarely 
noticeably differentiated; perichztial leaves ovate or ovate- 
lanceolate, acute or sometimes short acuminate, costate to the 
erect apex, cells linear or nearly so, entire or denticulate at ape> 
Sporophyte medium to large, 1.5 to 3.5 long: seta 180 to 
240¢ in diameter, purple at base, gradually passing to light 
brown or yellow above; central strand well developed, 25 sa 
45m in diameter, of sixteen to thirty-five rows of cells; cortex 
of two to three layers of cells 6 to 12m in diameter ; cells of 
ground tissue abruptly larger than cortical cells, 13 to 20F) larg- 
