ALISMACEAE. 55 



fourth their length; fruiting heads 8 mm. in diameter. In swamps, 111. to N. C. 

 and Fla., west to Mo. and Tex. June-July. 



2. Echinodorus cordifolius (L.) Griseb. Upright Bur-head. (I. F. f. 191.) 

 Leaves variable in form, often broadly ovate, obtuse, cordate at the base, 15-20 

 cm. long and wide, but in smaller plants sometimes nearly lanceolate, acute at each 

 end and but 2-5 cm. long; petioles angular, striate; scapes I or more, erect, 12-40 

 cm. tall; flowers 3-6 in the verticils; pedicels erect after flowering; sepals shorter 

 than the heads ; petals 4-6 mm. long; stamens often 12; styles longer than the 

 ovary; fruiting heads very bur-like, 4-6 mm. in diameter ; achenes about 3 mm. 

 long, narrowly obovate or falcate, 6-8-ribbed; beak apical, oblique, about one-har* 

 the length of the achene. In swamps and ditches, 111. to Fla., Mo. and Tex. Alsc 

 in tropical America. June-July. {E. rostratus Engelm.) 



3. LOPHOTOCARPUS T. Durand. 



Annual, bog or aquatic herbs with basal leaves, and simple erect or rarely 

 branching scapes bearing flowers in verticils of 2-3 at the top. Sepals 3, distinct, 

 persistent, erect after flowering and enclosing or enwrapping the fruit. Petals 

 white, deciduous. Receptacle strongly convex. Bracts membranous, those of the 

 lower verticils orbicular or ovate and obtuse, connate at the base, those of the stam- 

 inate flowers lanceolate and acute, free, or connate. Stamens 9-15, hypogynous, 

 inserted at the base of the receptacle. Filaments flattened. Pistils numerous; 

 ovule solitary, erect, anatropous; style elongated, oblique, persistent. Achenes 

 winged or crested. Embryo horseshoe-shaped. [Greek, signifying crested fruit.] 

 About 9 species, the following of E. N. Am., 2 in W. N. Am., the others of tropical 

 America. 



Leaves with sagittate or hastate blades, seldom bladeless. Plants growing in fresh-water 

 ponds and marshes. 

 Basal lobes of the leaves widely divergent ; large plants, 2-4 dm. high : petioles 



spongy, thick. 1. L. calycinus. 



Basal lobes not widely divergent ; low plants, 1-1.5 dm. high ; petioles slender. 



2. L, depauperatus. 

 Leaves mostly bladeless phyllodes. Submersed seashore and tidal-flat aquatics. 



Phyllodes thick, spongy, nodose, 1-3 dm. long. 3. L. spongiosus. 



Phyllodes flat, spatulate, not nodose, 3-7 cm. high. 4. L. spathulatus. 



1. Lophotocarpus calycinus (Engelm.) J. G. Smith. Leaves floating or 

 ascending, entire, hastate, sagittate, or triangular crescent-shaped, the basal lobes 

 spreading, ovate, acute or acuminate, the apex acute or obtuse, the blade varying 

 from 10-20 cm. long, sometimes 30 cm. wide at the base. Scape simple, weak and 

 at length decumbent, shorter than the leaves ; verticils of flowers 2-5 ; fertile pedi- 

 cels very thick, recurved in fruit, equalling or longer than the slender sterile ones ; 

 petals 6-10 mm. long ; filaments papillose, about as long as the anthers ; achene 

 cuneate, 2 mm. long, narrowly winged on the margins, tipped with a short hori- 

 zontal triangular beak. In swamps, N. B. to Va. and La., Okla. and S. Dak. 

 July-Sept. (Sagittaria calycina Engelm.) 



2. Lophotocarpus depauperatus (Engelm.) J. G. Smith. Sagittaria caly- 

 cina depanperata Engelm. in herb. Low, 10-15 cm. high ; petioles slender, 

 ascending ; blades elliptic, hastate or sagittate, acute, 3-nerved, 1.8-3.3 cm. 

 long, the basal lobes divergent ; scape half as long as the leaves ; fertile pedicels 

 slender, 8-25 mm. long ; fruiting head depressed-globose, 6.5-8 mm. in diam- 

 eter ; achenes broadly cuneate, 1.5 mm. long, 2 mm. wide, the slender hori- 

 zontal beak one-third the width of the body. Margins of ponds, Wis. to the Ind. 

 Terr. June-Sept. 



3. Lophotocarpus spongiosus (Engelm.) J. G. Smith. Sagittaria calycina 

 spongiosa Engelm. Submersed aquatic, with thick, spongy nodose phyllodes and 

 scapes 10-30 cm. high ; blades 5-10 cm. long, spatulate and obtuse, or elliptic 

 and truncate, or hastate or sagittate with narrow, falcately-divergent, acute lobes 

 2-10 mm. wide, often half as long as the blade ; scape simple, terete, spongy, half 

 the length of the petioles, at length decumbent, bearing 2 or 3 verticils of 1-3 

 flowers each ; fertile pedicels 3-6 mm. thick, 10-35 cm. long ; fruiting head 



