ALISMACEAE. 5 



Family 3. NAIAD ACEAE. Naias Family. 



Mostly fresh-water herbs. Leaves mainly opposite : blades mostly 

 toothed, the bases dilated. Flowers dioecious or monoecious, axillary: 

 staminate a single stamen and a double jierianth : i)istillate an ovai-y with 

 a style and 2-4 stig-mas. Fruit drui)aceous or a nutlet. 



1. NAIAS L. Plants submerged, usually iu dense tufts. Leaves narrow, 

 but short, often toothed on the midrib as well as on the margins. 



1. N. flexilis (Willd.) Rost. & Schmidt. Stems slender: leaves many, rather 

 close together; blades 11-28 mm. long, mostly acuminate, with 50-60 marginal 

 teeth: drupelets 3-4 mm. long, the pericarp shining, with 30-50 rows of delicate 

 reticulations. — Everglades and streams. 



Order ALISMALES. 



Marsh or aquatic herbs. Leaves alternate, mere phyllodia, or with 

 dilated blades. Flowers regular. Perianth of sepals and usually also of 

 petals. Androecium of 3-6 stamens or more. Gynoecium of 3-many 

 carpels. 



Sepals and petals nearly similar, or the petals wanting : carpels coherent during 

 anthesis, at maturity forming a capsular or follic- 

 ular fruit. Fam. 1. Scheuchzeriaceae. 



Sepals and petals very dissimilar : carpels distinct, at 



maturity forming a head or whorl of achenes. Fam. 2. Alismaceae. 



Family 1. SCHEUCHZERIACEAE. Arrow-grass Family. 



Perennial lierlis. Leaves narrow or slender above the dilated bases. 

 Flowers perfect in spikes or racemes. Perianth herbaceous. Gynoecium 

 3-6-carpellai-y. Style wanting or obsolete. Fruit of 3-6 turgid carpels. 



1. TRIGLOCHIN L. Acaulescent herbs, the perianth inconspicuous. 



1. T. striata E. & P. A glabrous plant of salt marshes. Leaves 2-3 dm. long, 

 attenuate: racemes 2-15 cm. long: sepals ovate or oval, less than 1 mm. long, 

 greenish or light yellow: fruit 1.5-2 mm. in diameter, each carpel 3-ribbed. — 

 Hanmiocks and shores of Bay Biscayne. — Arrow-grass. 



Family 2. 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 achenes. 



1. SAGITTARIA 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. — 

 Arrow-head. 



Plants floating : pedicels of the pistillate flowers thickened and reflexed at maturity : 



achene-heak erect. 1. S. loiata. 



Plants erect : pedicels of the pistillate flowers slender, ascending : 

 achene-beak horizontal or ascending. 

 Achenes obovate : filaments about as long as the anthers : bracts 



acute or acuminate, glabrous. 2. S. lancifoUa. 



Achenes cuneate : filaments longer than the anthers : bracts ob- 

 tuse, papillose. .3. S. falcata. 



