ALISMACEAE 9 



1. NaiasflexiUa (Willd.)Rost. & Schmidt. Slender Naias. (Man. 

 p. 51 ; I. F. /. 180.) In ponds and streams, nearly throughout N. A. — 

 Pennsylvania: Northampton; Delaware; Lancaster; Hunting- 

 don ; Chester. 



2. Naias graoillima (A. Br.) Morong. Thread-like Naias. (Man. 

 p. 51 ; I. F./. 182.) In ponds and pools, Mass. to Del. and Mo. — Penn- 

 sylvania: Bucks, Bristol. 



Orders. ALISMALES. 



Petals nearly similar to the sepals : anthers long and narrow : carpels coherent. 



Fam. I. SCHEUCHZERIACEAE. 



Petals very different from the sepals : anthers short and thick : carpels not co- 

 herent. Fam. 2. Alismaceae. 



Family i. SCHEUCHZERIACEAE Agardh. Arrow-grass Family. 

 Plants scapose : flowers many in an elongated spike or spike-like raceme. 



I. Triglochin. 

 Plants caulescent : flowers few in a short, loose raceme. .i. Scheuchzeria. 



1. TRIGLOCHIN L. 

 1. Tiiglochln maritima L. Seaside Arrow-grass. (Man. p. 53 ; 

 I. F.y. 186.) In bogs, or salt marshes, Lab. to N. J., Alaska and Calif. 

 — Pennsylvania : Erie, Presque Isle. 



2. SCHEUCHZERIA L. 



1. Scheuchzeria palustris I/. Scheuchzeria. (Man. p. 53; I. F./. 

 r8y.) In bogs. Lab. to Br. Col., N. J., Wise, and Calif. — Pennsylvania: 

 Pike ; Monroe ; Wayne ; Carbon ; Tioga ; Lycoming. 



Family 2. ALISMACEAE DC. Water-plantain Family. 



Carpels in a ring on a flat receptacle. 1. Alisma. 



Carpels crowded in many series on a convex or gl9bose receptacle. 



2. Sagittaria. 

 1. ALISMA L. 



1. Alisma Plantago-aquatica L. WATER Plantain. (Man. p. 54 ; 

 I. F. f. 188. ) In mud or shallow water, nearly throughout N. A. — 

 Pennsylvania : Monroe, Pocono ; Northampton ; Delaware ; Ches- 

 ter ; Lancaster ; Huntingdon ; Allegheny ; Franklin ; Erie. 



2. SAGITTARIA L. 



A. Pedicels of the pistillate flowers slender, ascending, not reflexed. 

 a. Leaf-blades sagittate. 

 Beak of the achene erect, the tip sometimes recurved. 

 Pedicels of the pistillate flowers shorter than their bracts. 



1. 5. longirostra. 

 Pedicels of the pistillate flowers longer than their bracts. 



2. 5". Engelmanniani, 

 Beak of the achene lateral, horizontal, or oblique. 3. 5. latifolia. 



