ALISMACEAE. 



Vol. I. 



4. Lophotocarpus spathulatus J. G. 



Smith. Spatulate Lophotocarpus. 

 Fig. 230. 



Lophotocarpus spathulatus J. G. Smith, Rep. 

 Mo. Bot. Gard. 11: 149. 1899. 



Plants aquatic ; leaves less than 4' tall, 

 the petioles stout, not conspicuously septate, 

 the blades linear or spatulate dilations at 

 the top of the petioles, or wanting; scape 

 shorter than the leaves, stout but weak, the 

 inflorescence with but one whorl ; sepals 

 ovate to orbicular-ovate, becoming ii" 

 long; fruiting pedicels stout, about 5" long 

 or less; fruit-heads 2V-3" in diameter; 

 achens cuneate, i"-i" long, the beak much 

 below the top of the achene-body, the nar- 

 row dorsal wing thin. 



On sandy beaches above salt-water, New- 

 buryport, Massachusetts. July-Sept. 



5. SAGITTARIA L. Sp. PI. 993. 



1753- 



Perennial aquatic or bog herbs, mostly with tuber-bearing or nodose rootstocks, fibrous 

 roots, basal long petioled nerved leaves, the nerves connected by numerous veinlets, and erect, 

 decumbent or floating scapes, or the leaves reduced to bladeless phyllodia (figs. 241, 242). 

 Flowers monoecious or dioecious, borne near the summits of the scapes in verticils of 3's, 

 pedicelled, the staminate usually uppermost. Verticils 3-bracted. Calyx of 3 persistent sepals, 

 those of the pistillate flowers reflexed or spreading in our species. Petals 3, white, deciduous. 

 Stamens usually numerous, inserted on the convex receptacle ; anthers 2-celled, dehiscent by 

 lateral slits ; staminate flowers sometimes with imperfect ovaries. Pistillate flowers with 

 numerous distinct ovaries, sometimes with imperfect stamens; ovule solitary; stigmas small, 

 persistent. Achenes numerous, densely aggregated in globose or subglobose heads, com- 

 pressed. Seed erect, curved ; embryo horseshoe-shaped. [Latin, referring to the arrow- 

 shaped leaves of some species, known generally as Arrow-head or Arrow-leaf.] 



About 40 species, natives of temperate and tropical regions. Besides the following, some 18 

 others occur in southern and western North America. Type species : Sagittaria sagittifolia L. 



Fertile pedicels slender, ascending, not reflexed in fruit. 

 Leaf-blades sagittate or hastate. 



Basal lobes one-fourth to one-half the length of the blade. 

 Beak of the achene erect. 



Achene long-beaked, the beak mostly l /i the length of the body or more. 



Achene obovate or orbicular-obovate, usually with i facial wing/, i. S\ longirostra. 

 Achene cuneate, usually with 2 prominent facial wings. 2. S. Engelmanniana. 



Achene short-beaked, the beak mostly ;4 the length of the body or less. 



Achene with thick nearly equal wings, the blunt beak over the inner edge of the 



ventral wing. 3. S. cuneata. 



Achene with thin unequal wings, the sharp beak over the 

 ventral wing. 

 Beak of the achene horizontal. 



Achene with nearly even faces : bracts and pedicels glabrous. 5. 

 Achene faces prominently winged ; bracts and pedicels pubescent. 



outer edge of the 

 SV brevirostra. 



S. latifolia. 

 6. 5. pubescent. 

 S. longiloba. 



Basal lobes two-thirds to three-fourths the length of the blade. 

 Leaves entire, or rarely hastate or cordate. 



Filaments tapering upward ; leaves seemingly pinnately veined. 

 Filaments glabrous ; bracts connate. 

 Filaments cobwebby-pubescent ; bracts mostly distinct. 

 Filaments abruptly dilated, pubescent ; veins distinct to the base. 

 Fruiting heads sessile or very nearly so. 

 Both staminate and pistillate flowers pedicelled. 



Leaves with terete or 3-sided blades, often imperfectly developed. 



Achene with thick merely uneven facial wings or ridges, the beak erect. 



n. S. teres. 

 Achene with thin crested facial wings, the beak oblique. 12. 

 Leaves with flat blades. 



Filaments suborbicular ; anthers longer than the filaments. 13. 

 Filaments oblong; anthers about as long as the filaments. 14. 

 Fertile pedicels stout, reflexed in fruit ; filaments dilated. 



Filaments pubescent; leaf-blades ovate or ovate-elliptic. 15. S. platyphylla. 



Filaments glabrous ; leaves linear-lanceolate or reduced to phyllodia. 



Filaments about as long as the anthers ; achene with 3 undulate or slightly toothed crests. 



16. -V. subulata. 



8. 5\ ambigua. 



9. S. falcata. 

 10. 5\ rigida. 



S. cristata. 



S. Eatonii. 

 S. graminea. 



