ALISMACE.E. 377. 



1. S. sagittifolia Willd. : leaves sagittate, acute ; lobes acute> 

 straight, lanceolate. 



a. latifolia Torr. : leaves broad ovate, rather obtuse ; lobes ovate, 

 slightly acuminate, straight. S.- latifolia Pursh. 



b. hastata Torr. : leaves . oblong-lanceolate, acute ; lobes spread- 

 ing, lanceolate, long, acuminate ; flowers mostly dioecious. 

 S. hastata Pursh. *' v 



c. gracitis Torr. : leaves linear; lobes much spreading, linear, 

 very long and acute. S. gracilis Pursh. 



d. pubescens Torr. : leaves and stem pubescent ; bracts and calyx 

 very pubescent. S. pubescens Muhl. -'. 



HAB. Ponds. Can. to Car. July, Aug. If. Scape 12 feet 

 high. Leaves large. Flowers white, whorled in threes. The 

 above account of this species which is from Torrey's Compen- 

 dium, will show the very variable character of the plant. 



Arrow-head. 



2. & obtusa Wittd,. : leaves sagittate, dilated-ovate, rounded at the 

 the extremity, mucronate ; lobes approximate, oblong, obliquely acu- 

 minate, straight ; flowers dioecious ; sterile scape branched at base. 



HAB. Ditches and ponds. Perm, to Vir. July. If. Leaves the 

 size of Calla palustris. Flowers white. The plant affords a 

 milky sap which hardens into a white and hyaline gum. Nutt. 



3. S. heterophylla Pursh : leaves simple, linear and lanceolate, acute 

 at each end, or elliptical and sagittate, with the lobes linear and di- 

 varicate ; scape simple, few-flowered ; flowers monoecious, the fertile 

 imbsessile ; bracts short, suborbiculate. 



HAB. Bogs and ditches. Penn. to Vir. July. 2_. Scape a 

 foot high. Leaves 21-2 inches long. The species is easily dis- 

 tinguished by its fertile flowers being sessile. 



4. 8. rigida Pursh : leaves narrow-lanceolate, carinate below, rigid, 

 very acute at each end ; scape branched ; flowers monoecious. 



HAB. Deep water near Oswego Falls, N. Y. July, Aug. 

 Pursh. If. Grows in a depth of more than 7 feet water. Pe- 

 tioles strong and stiff. Flowers very numerous. 



5. 8. simplex Pursh : leaves linear-lanceolate, acute, narrowed to- 

 wards the base ; scape simple, many-flowered ; flowers dioecious ; 

 bracts and calyx obtuse and rounded. 



HAB. Ponds. N. J. Aug. 2J..^Scape 812 inches high. 

 Leaves 6 inches long, 1-2 an inch wide. Flowers small, 12 18 

 in a scape. 



6. $. acuttfolia Pursh : leaves acutely subulate, sheathing at base, 

 convex on the back ; scape simple, few-flowered ; flowers monoecious ; 

 bracts dilated, acuminate. 



HAB. Muddy shores.' Mass. N. Y. and Penn. July, Aug. 1(. 

 Scape 6 inches high. Flowers pedunculate. Found by Dr. 

 Bigelow near Boston, and by Dr. S. B. Mead at Peekskill, N. Y. 



7. S. pusiila Nutt. : leaves linear, obtuse and short, the summits foli- 

 aceous ; scape simple, shorter than the leaves ; flowers monoecious, 



32* 



