6 Ea eR ier eae AT 
SAGITTARIA AND LOPHOTOCARPUS. 49 
+ + Achenium narrowly obovate, with a long, stout, erect beak; 
leaves hastate, veins free to the base; filaments dilated, pubescent; 
anthers short-oblong; fertile flowers subsessile. 
S. riema Pursh, Fl. Am. Sept. 397 (1814). S. heter- 
ophylia Pursh, |. c. 396 (1814). &. heterophylla var. 
angustifolia Engelm. in A. Gray; Man. Ed. 5, 494 
(1867), and var. elliptica Engelm. |. c. 494 (1867). 
Monoecious, erect or ascending, 1 to 8 dm. high; leaves 
5 to 20 cm. long, varying from elliptical, linear or lanceo- 
late to broadly ovate, apex acute or abruptly rounded, base 
entire, or cordate, or with 1 or 2 narrow divergent lobes, 
veins 7 to 9; scape simple, weak, sinuous, at length decum- 
bent, shorter than the leaves, usually geniculate at the 
lower verticil; bracts ovate, obtuse, 4 to 8 mm. long, 
deeply connate; 1 or rarely 2 verticils fertile, the pedicels 
not exceeding 1 cm. long; filaments usually exceeding the 
anthers; achenium narrowly winged on both margins, 3 to 
4 mm. long, crested above; fruiting head echinate with 
the beaks of the achenia, 8 to 15 mm. in diameter, almost 
sessile.— In stagnant or running water, rooting in the mud. 
Quebec to Tennessee, west to Minnesota and Nebraska.— 
Plate 18. 
Specimens differ greatly in size and form of leaf, differ- 
ences depending largely on the habitat of the plant. When 
growing in deep pools or running streams, the petioles 
become thick, rigid and elongated, with long narrowly 
lanceolate spongy blades, or the tapering attenuate 
phyllodia are bladeless. This is the S. heterophylla rigida 
of the manuals and collectors. When growing in shallow 
ponds or in simply muddy places, the petioles are weaker, 
and the blade elliptical ovate and usually smaller, and 
the habit erect or ascending. This form is the 8S. 
heterophylla elliptica of collectors. Depauperate plants 
from shallow water or simply muddy places, with linear 
elliptical oblong leaves, are the S. heterophylla angustifolia 
of collectors. Toward the southern limit of its range, the 
plants are usually of ranker growth, with larger more often 
4 23 
