40 SCHEUCHZERIACEAE 



Leaf-margins with prominent sharp teeth. 3. N. conferta. 

 Sheaths equilateral, with margins entire or coarsely few-toothed. 



Leaves about 0.5 mm. broad, with 15-24 marginal teeth : internodes filiform. 4. N. gracuis. 



Leaves about 2 mm. broad, with 6-10 marginal teeth : internodes stout. 5. N. marina. 



1. Naias Guadalup6nsis (Spreng. ) Moron g. Stems filiform or hair-like, 3-7 dm. 

 long, widely branched : leaves opposite, sometimes clustered ; blades narrowly linear, 

 10-20 mm. long, acute, often curved, with 40-50 minute teeth on each margin : drupelets 

 2 mm. long ; pericarp granular, marked with 16-20 rows of rectangular or hexagonal reticu- 

 lations, the long axis transverse. [N. mwrodon A. Br.] 



In ponds and lakes, Nebraska to Oregon, Florida, Texas and throughout'.tropical America. Sum- 

 mer and fall. 



2. Naias ftexilis ( Willd. ) Rostk. & Schmidt. Stems slender, 2-18 dm. long, forking ; 

 internodes commonly armed with teeth : leaves numerous ; blades narrowly linear, 1-2. 5 cm. 

 long, acute or acuminate, with 25-30 minute teeth on each margin : drupelets ellipsoidal, 

 2-4 mm. long ; pericarp lustrous, finely sculptured, with 30-50 rows of square or hexagonal 

 reticulations. 



In streams and ponds, nearly throughout North America. Summer. Also in Europe. 



3. Naias conferta A. Br. Similar to N. flexilis in habit. Leaves slender, the mar- 

 gins with prominent sharp teeth. 



In tidal creeks, Milton, Florida. Summer. Also in tropical America. 



4. Naias gracilis (Morong) Small. Stems filiform, forking ; branches erect or as- 

 cending, the internodes 2.5-10 cm. long, with a few teeth near the upper ends : leaves 

 slender ; blades 2-4 cm. long, about 0.5 mm. broad, with 15-24 marginal teeth and few 

 dorsal teeth : sheaths with 2-3 teeth on each margin : drupelets barely 4 mm. long, slightly 

 oblique ; pericarp with about 25 rows of square or irregular-oblong reticulations. [N. 

 marina var. gracilis Morong.] 



In creeks and ponds, Florida. Spring to winter. 



5. Naias marina L. Stems stout, several dm. long, flattened, branching, commonly 

 armed with tooth-like spines about twice as long as broad : leaves opposite or whorled ; 

 blades linear, 10-25 mm. long, about 2 mm. wide, acute, with 6-10 spine-like teeth on 

 each side and sometimes several on the back of the midrib : drupelet oblong, 4-5 mm. 

 long ; pericarp granular, reticulated. [N. major All. ] 



In lakes, New York to California and Florida. Summer. Also in Europe. 



Order 3. ALISMALES. 



Marsh or aquatic herbs, with rush-like or spongy tissues. Leaves alternate, 

 various, slender and stiff, or with dilated blades. Flowers perfect, monoecious 

 or dioecious. Perianth of 2 often dissimilar series (sepals and petals). Androecium 

 of 3-6 stamens. Gynoecium of 3-many distinct carpels. Endosperm wanting. 



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



Fam. 1. SCHEUCHZERIACEAE. 

 Petals very different from the sepals : anthers short and thick: carpels 



not coherent. Fam. 2. ALISMACEAE. 



FAMILY 1. SCHEUCHZERIACEAE Agardh. ARROW-GRASS FAMILY. 



Perennial marsh herbs, with scapes or normal stems. Leaves alternate : 

 blades rush-like, narrow, often very slender from a dilated ba^e. Flowers per- 

 fect, in terminal spikes or racemes : perianth of 4-6 members in 2 series, or the 

 corolla wanting, persistent or deciduous. Androecium mostly of 4-6 stamens. 

 Filaments variable in length. Anthers usually 2-celled, extrorse. Gynoeciuin 

 of 3-6 partially united carpels. Stigmas sessile or nearly so. Ovules 1 or 2 in 

 each cavity, anatropous. Fruit of 3-6 separating dehiscent or indehiscent 

 carpels. Seeds 1 or 2 in each carpel. Embryo straight. 



1. TRIGLOCHIN L. 



Acaulescent marsh herbs, commonly with abbreviated rootstocks. Leaves basal, 

 sheathing each other by their dilated membranous bases : blades narrow, elongated. Scapes 

 slender, erect, simple. Spikes or racemes terminal. Perianth inconspicuous : sepals 3 : 

 petals 3, remote from the similar sepals, or wanting. Stamens 3-6 : anthers 2-celled, sessile 

 or nearly so. Pistils 3-6, 1 -celled : stigmas 3-6, sessile or nearly so, plumose. Ovule soli- 



