IO2 



ALISMACEAE. 



VOL. 1. 



10. Sagittaria rigida Pursh. Sessile-fruited Arrow-head. Fig. 240. 



Sagittaria rigida Pursh, Fl. Am. Sept. 397. 1814. 

 Sagittaria heterophylla Pursh, Fl. Am. Sept. 396. 1814. Not 

 Schreb. 1811. 



Monoecious, glabrous, scape simple, weak, curving, as- 

 cending or decumbent, shorter than the leaves. Leaves 

 very variable, linear, lanceolate, elliptic or broadly ovate, 

 acute or obtuse at the apex, entire or with i or 2 Short or 

 slender basal lobes ; bracts ovate, obtuse, 2" -4" long, united 

 at the base or sometimes distinct ; heads of fruit sessile or 

 very nearly so; pedicels of the sterile flowers \'-\' long; 

 filaments dilated, mostly longer than the anthers, pubes- 

 cent; achene narrowly obovate, \\"-2." long, winged on 

 both margins, crested above, tipped with a stout nearly 

 erect beak of about one-fourth its length. 



In swamps and shallow water, Quebec to Minnesota, south 

 to New Jersey, Tennessee, Missouri and Nebraska. Petioles 

 rigid when growing in running water. July-Sept. 



ii. Sagittaria teres S. Wats. 

 Fig. 241. 



Slender Sagittaria. 



Sagittaria teres S. Wats, in A. Gray, Man. Ed. 6, 555. 1890. 



Monoecious, glabrous, scape slender, erect, simple, 6'-i8' 

 long, bearing only 1-3 verticils of flowers. Leaves usually 

 reduced to elongated terete nodose phyllodia or some of 

 them short and bract-like, one or two of the longer ones 

 occasionally bearing a linear blade ; bracts ovate, obtuse, 

 about \\" long, much shorter than the filiform fruiting 

 pedicels which are longer than the sterile ones ; flowers 

 6"-8" broad ; stamens about 12, their dilated filaments 

 pubescent, shorter than the anthers ; achene broadly obo- 

 vate, l" long, the ventral margin winged, the dorsal 

 7-n-crested, the sides bearing several crenate crests, the 

 .beak short, erect. 



In ponds, Massachusetts to South Carolina. Aug.-Sept. 



12. Sagittaria cristata Engelm. Crested Sagittaria. Fig. 242. 



Sagittaria cristata Engelm. ; Arthur, Proc. Davenport Acad. 

 4: 29. 1882. 



Monoecious, scape slender, erect, \-2.\ high, simple, 

 bearing 4 or 5 verticils of flowers at or above the sur- 

 face of the water. Leaves long-petioled, spongy and 

 rigid, reduced to slender phyllodia or bearing linear- 

 lanceolate or elliptic blades 2'-^' long and 3"-i2" wide; 

 bracts acute, 2" -4" long, much shorter than the slender 

 fertile pedicels; flowers 8"-io" broad; stamens about 

 24; filaments dilated, pubescent, at least at the middle, 

 longer than the anthers ; achene obliquely obovate, the 

 dorsal margin with a broad crenate wing, the ventral 

 straight-winged, each side bearing 2 crenate crests, the 

 beak short, oblique. 



In shallow water, Iowa and Minnesota. Phyllodia are 

 commonly developed from the nodes of the rootstock. 

 July-Aug. 



