ALISMACEAE. 7 



Family 1. ALISMACEAE. Water-plantain Family. 



Annual or perennial herbs. Leaves basal, the blades flat, often with 

 basal lobes, or mere phyllodia. Flowers perfect, monoecious, or dioecious, 

 whorled. Sepals herbaceous. Petals tender, white or pink. Gynoecium 

 of few to many carpels. Style manifest. Fruit a head of flattened carpels. 



Carpels borne In one series : achenes verticillate. 1. Alisma. 



Carpels borne in several series : achenes capitate. 2. Sagittaeia. 



1. AliISMA L. Leaves without basal lobes. Flowers perfect, in com- 

 pound panicles. Stamens mostly 6. Achenes in 1 whorl. 



1. A. subcordatum Eaf. Leaf-blades ovate, usually broadly so, or orbicular- 

 ovate, mostly pointed: sepals suborbicular, about 2.5 mm. long at maturity: 

 petals 2-4 mm. long: fruit-heads 3-4 mm. wide; achenes less than 2.5 mm. 

 wide, the beak below the top. — Common, in shallow water and swamps. — 

 Spr.-f all. — Water-plantain. 



2. SAGITTAE.IA L. Leaves often with basal lobes, sometimes lobeless or 

 mere phyllodia. Flowers monoecious or dioecious, the upper ones usually 

 staminate. Stamens mainly numerous. Achenes numerous, in dense heads. — 

 Sum. and fall. — Arrow-head. Wampee. 



Filaments dilated, pubescent. 



Pistillate flowers pedicelled : achene with a minute horizontal beak below the top 



of the body. 1. S. graminea. 



Pistillate flowers sessile : achene with a large, ascending beak 



at the top of the body. 2. 8. rigida. 



Filaments slender, glabrous. 



Achenes with liorizontal or nearly horizontal beaks. 



Inflorescence-rachis, bracts, pedicels, and sepals glabrous. 3. S. latifolia. 



Inflorescence-rachis, bracts, pedicels, and sepals pubescent. 4. S. pubescens. 

 Achenes with erect beaks. 5. 8. longirostra. 



1. S. graminea Michx. Leaf -blades linear, lanceolate, or elliptic, 5-15 cm. 

 long, or wanting: scapes 1-6 dm. tall, with few-many flower-whorls: bracts 

 ovate, united to about the middle: fruit-heads less than 10 mm. thick: achenes 

 1.5 mm. long, winged, the minute beak horizontal. — Susquehanna valley and 

 adjacent parts. Rather rare, in sand or shallow water. Chiefly on schists. 



2. S. rigida Pursh. Leaf -blades linear to broadly ovate, sometimes with basal 

 lobes, 5-20 em. long: scapes weak, 1-8 dm. long, with 5-9 flower-whorls: fruit- 

 heads 8-15 mm. thick, sessile or nearly so: achenes 3-4 mm. long, winged, the 

 beak ascending. — Conestoga Creek and tributaries. Rather rare, usually in 

 shallow water. — Limestones. 



3. S. latifolia "Wilkl. Leaf -blades broad, 15-40 cm. long, glabrous, the basal 

 lobes narrower and rather shorter than the terminal one: scapes 3-6 dm. tall: 

 pedicels of pistillate flowers much longer than the acute bracts: fruit-heads 

 15-30 mm. thick: achenes about 3 mm. long, the beak ascending or recurved. 

 — Common, in swamps, ponds, or shallow water along streams. 



4. S. pubescens Muhl. Leaf-blades 8-25 cm. long, with the terminal lobe more 

 rounded than in no. 3, puberulent or hirsute: scapes 3-6 dm. tall: pedicels of 

 pistillate flowers about as long as the obtuse bracts or slightly longer: fruit- 

 heads 8-15 mm. thick: achenes 2-3 mm. long, the beak horizontal or somewhat 

 declined. — M.S. Rather rare, in swamps and wet places. — Limestones, schists. 



5. S. longirostra (Micheli) J. G. Smith. Leaf -blades 10-25 cm. long, the 

 terminal lobe broadly ovate, the basal lobes as long but narrower: scapes 4-8 

 dm. tall, with a few flower-whorls: bracts acuminate: fruit -heads 12-18 mm. 

 thick, short-pedicelled: achenes 4 mm. long, with facial wings, the dorsal wing 

 partially crenate, the beak erect. — Lower Susquehanna valley. Rare, usually 

 in shallow water. — Schists. 



